The relationship between the use of these two substances has a basis in the biological connection between them, as the endogenous opioid system is an underlying mechanism for several behavioral outcomes related to nicotine . Like marijuana, nicotine is involved in anti-nociception via endogenous opioid system mediation, suggesting that nicotine is used for the selfmedication of pain ; and in fact, nicotine heightens the anti-nociceptive effects of both opioids and marijuana . Several studies have documented common use patterns among tobacco, marijuana, and opioids/PPRs . For example, a prospective study of NESARC data demonstrated that early-onset of smoking cigarettes increased the odds of beginning opioid use and that frequency of both cigarette and marijuana use increased the odds of beginning opioid use, re-initiating opioid use after previously stopping, and continuing opioid use among current users . Thus, the three substances share anti-nociceptive actions mediated by the endogenous opioid system, and evidence indicates that marijuana and nicotine use predict opioid use among adults. From 2003 to 2012, NSDUH data revealed a significant increase in the co-use of marijuana and tobacco . Further, smoking tobacco is significantly associated with cannabis dependence . Given the national trend toward marijuana legalization, co-use is likely to increase. Cigarette smokers and marijuana users are a crucial population to study, as nicotine and marijuana share mechanisms of action with each other and with opioids, and use of each substance has been shown to be associated with use of opioids/PPRs . However, whether there is an association between prevalence of marijuana and PPR use among current smokers has not been determined. The present study addresses this gap by using the Tobacco Attitudes and Beliefs Survey II to investigate the relationship between marijuana use and PPR use among current cigarette smokers. This study examines 1) the likelihood of PPR use by marijuana use and 2) the frequency of marijuana use and current PPR use.

Findings may help elucidate whether marijuana use is associated with PPR use, and if so,pot for cannabis whether marijuana is used as a substitute or complement to PPR use. This is a cross sectional analysis of data from the TABS II, a web-based longitudinal survey of U.S. adult former and current cigarette smokers, aged 24 years old and older. The survey included topics such as individuals’ use of tobacco, tobacco-related products, marijuana, and other substances including PPRs. The present analysis used demographic data from Wave 1 from August 2015 . Wave 3 data were collected in August 2016 and included survey items on marijuana use and new items on PPR use . Surveys were administered by Qualtrics, which uses a combination of online panels to establish national samples from which survey participants can be randomly selected. Qualtrics invited potential participants to take the survey via an email notification and offered them a $10 incentive to complete each survey wave. For Wave 1, 2,378 individuals clicked on the survey link, and 819 went on to complete the survey, yielding a completion rate of 34.4% . Current smokers were included in the current analysis. The TABS II project was approved by the UCSF Institutional Review Board. Cigarette use.—Participants were categorized as a current cigarette smoker if they responded “yes” to the question, “Are you a current cigarette smoker?” and if they responded with any number of days greater than 0 for the question “During the last 7 days, on about how many days did you smoke cigarettes, even 1 or 2 puffs” or to the question “During the last 7 days, on about how many days did you smoke menthol cigarettes, even 1 or two puffs.” The question “On average, how many cigarettes a day do you smoke?” was used to control for cigarette consumption in the analysis of the relationship between cannabis use and PPR use. Marijuana use.—Definitions of each user type were: “never users,” never used marijuana in their lifetime; “ever” users, used marijuana at least once in their lifetime, but not in the past 30 days; and “current” users, used marijuana in the past 30 days. If participants answered the question “During the last 30 days, on about how many days did you use marijuana, even 1 or 2 puffs?” with any number above 0, they were classified as a current user. If participants responded with “I have never tried marijuana” to the question asking “Which of the following forms of marijuana have you EVER used?” then they were classified as a never user.

If they responded to this question with any other option besides “Don’t know/refused” and if they were not categorized as a current user, they were classified as an ever user. For the analysis involving frequency of marijuana use as a continuous variable, responses to the question “During the last 30 days, on about how many days did you use marijuana, even 1 or 2 puffs?” were used. Medical marijuana lawstatus in state of residence.—Participants were categorized as: 1) no legal medical marijuana in state of residence, 2) legal medical marijuana for less than 10 years in state of residence, or 3) legal medical marijuana for 10 or more years in state of residence. PPR use.—PPR users were categorized as “never” users if they reported they had never used PPRs in their lifetime, as “ever” users if they had used PPRs but not in the past 30 days, and “current” users if they had used PPRs in the past 30 days. If participants selected “Prescription pain relievers” for the following two questions, they were classified as current PPR users: 1) “Have you EVER used any of the following substances? Mark all that apply” and 2) “Have you used any of the following substances in the PAST 30 DAYS? Mark all that apply.” If participants selected “Prescription pain relievers” in the first question , but did not select them in the second question , then they were classified as ever users. If they did not select “Prescription pain relievers” in the question inquiring about ever use, they were classified as never users. Statistical Analysis—Descriptive analyses were used to test for normality. Chi-square tests were used for categorical variables , and an ANOVA was used for the continuous variables to compare sample characteristics between marijuana never users, ever users, and current users. For PPR status, a Bonferroni adjustment was made to account for multiple comparisons. A logistic regression was used to examine whether the frequency of marijuana use influenced PPR use among current marijuana users. SAS University Edition, which contains SAS Studio 3.6 and SAS 9.4, was used for all analyses.Participants ranged in age from 24 to 88 years old . The majority were female and Caucasian . On average,pot for growing marijuana participants smoked over 15 cigarettes per day . Table 1 presents demographic information and PPR status stratified by marijuana use. Chi-square tests and an ANOVA revealed no significant differences in sample characteristics across marijuana never, ever, and current users.

A significant difference was found between marijuana never, ever,and current users for PPR status . We tested three comparisons using SAS proc multest, which provides Bonferroni adjusted p values. A significant difference remained for the following PPR use groups: never vs. ever and never vs. current .As shown in Table 2, logistic regression was used to further examine the relationship between marijuana and PPR use, with PPR current use set as the reference category for the criterion variable and marijuana never use set as the reference category for the predictor variable. The model was adjusted for all sample characteristics, and compared to marijuana never users, both marijuana ever users and current users were more likely to have used PPRs in the past 30 days, with ever users having an AOR=2.58 and current users having an AOR=3.38 . A logistic regression was used to investigate the relationship between the frequency of marijuana use among current marijuana users and PPR use, and no significant results were found . Results suggest that adult current cigarette smokers have differential use of PPRs depending on their use of marijuana. Those who were current and ever marijuana users were over 2–3 times more likely to have used PPRs in the past 30 days, respectively, when compared to cigarette smokers who never used marijuana. Results support the findings of previous studies that addressed a possible complementary effect of marijuana use with PPR use. Novak, Peiper, and Zarkin analyzed NSDUH data in 2003 and 2013 and found that greater marijuana use was associated with more frequent PPR use. An analysis of NESARC data found higher levels of marijuana and cigarette use predicted initiation, re-initiation, and sustained opioid use ; and another study using NESARC data determined that marijuana use was associated with an elevated risk of using nonmedical prescription opioids three years later . Two Swedish teams found similar results. One study found a positive association between use of marijuana and unauthorized use of PPRs . In a re-analysis of a Swedish national household survey, non-medical PPR use was associated with both frequent cigarette smoking and marijuana use . Studies with adolescent and young adult samples found non-medical use of PPRs is associated with marijuana use . Though longitudinal studies are needed to make definitive conclusions about the nature of the relationship between marijuana and PPR use among cigarette smokers, the interface among biological effects of PPRs, marijuana, and nicotine could influence the strength and direction of this relationship. For one, PPRs and marijuana share anti-nociceptive effects, the two substances act on some of the same brain regions, and THC partly exerts its analgesic influence by relying on opioid receptors . Nicotine additionally interacts with the opioid system, and the systems have almost identical influences in key pleasure-sensing areas of the brain . Therefore, the behavioral responses to nicotine use and withdrawal are likely affected by the opioid system .

As with marijuana and opioids, nicotine has antinociceptive actions . Consequently, the interconnected neural activity and biological effects of nicotine, marijuana, and opioids could play a role in the relationship between PPR and marijuana use among cigarette smokers. Another explanation for the higher likelihood of current PPR use among ever and current marijuana users in cigarette smokers could be that some participants had used marijuana and/or PPRs to reduce pain symptoms. Epidemiologic and prospective cohort studies point to a relationship between smoking and chronic pain, with smokers having a greater likelihood of developing chronic pain disorders than non-smokers . And the most frequently reported reason for adult misuse of PPRs in 2015 was to alleviate physical pain . Our results do not support prior findings of a negative association between marijuana and PPR use. Boehnke, Litinas, and Clauw report that among individuals with chronic pain, use of medical marijuana was negatively associated with opioid use. Further, legalization of medical marijuana has been correlated with a drop in the number of hospitalizations attributed to opioid dependence/abuse and PPR ODs, and a decline in opioid OD mortality rates . States with medical marijuana dispensaries also report fewer PPR ODs, a reduction in PPR treatment admissions, and a decline in opioid-related deaths . However, none of these studies stratified their results by cigarette smoking status. As such, it is possible that the inclusion of only current cigarette smokers in the present study could help explain the discrepancy between the present findings and other results. Of note, studies investigating the effect of marijuana use on opioid/PPR use vary in their sample composition , use of covariates , and outcome measures . This variation in study design is likely responsible for some of the discrepant findings in the extant literature. As previous studies have not stratified their analyses by cigarette smoking status, our study provides an important and unique contribution to current evidence, and this dynamic helps to explain why our findings differ from those that found a negative relationship between marijuana and PPR use. We did not find a significant association between PPR use and frequency of marijuana use among current marijuana users. Our findings align with those of Lucas et al. , who determined that among Canadian medical marijuana users, there was no association between frequency of marijuana use and illicit drug substitution, though this finding is attenuated because their analysis was not stratified by cigarette use status. On the other hand, our findings contrast with those of Arterberry et al. , who reported that frequency of marijuana and cigarette use was predictive of opioid use among an adult sample in the NESARC. This dissimilarity may be due to differences in study design.

Several sources could be promoting misperceptions that marijuana use is safe and beneficial for pregnant and breastfeeding women. One potential source is social media, through which misinformation about maternal marijuana use receives increasing spread, attention, and engagement. Analyses of Twitter communications suggest an increasing engagement with misinformation about benefits of marijuana use during pregnancy and breastfeeding . The proliferation of online support groups advocating benefits of use while pregnant and breastfeeding suggests growing popularity in beliefs that marijuana is a safe and affordable treatment for discomfort, depression, and morning sickness ; that it is safe because it is plant-based and natural; and that it facilitates breastfeeding. Qualitative interviews with pregnant women have documented these beliefs but systematic, quantitative examinations of endorsements of these beliefs in communities remain lacking. Another potential source of misperceptions is the legalization of marijuana for recreational and medicinal use in a growing number of states and regions. This trend could foster expectations that marijuana must be a safe substance if it is legal to use and it must be healthy if it is prescribed for medicinal purposes such as pain and depression. Among pregnant women, risk perceptions about the use of marijuana during pregnancy have decreased in recent years and these decreases might partly explain the increases in marijuana use by pregnant and breastfeeding women . If maternal marijuana use is expected to rise in line with the increases in beliefs about its safety and benefits,mobile grow system then it is essential to determine which beliefs about specific risks and benefits are commonly held and which cultural and social groups are prone to misconceptions.

This information can be used to identify specific beliefs to address and target audiences for health communications aimed at promoting informed decisions about using marijuana by pregnant and breastfeeding women.Whereas it is important to understand beliefs about maternal marijuana use held by adults across societies, understanding beliefs held by vulnerable populations hold particular importance given the likely health disparities if risk-elevating beliefs common within these communities are not addressed through health communications and interventions. The San Joaquin Valley is home to vulnerable, underserved communities that struggle with significant health disparities and lack of access to health care resources . Latinos make up the majority of residents and, more generally, represent one of the fastest growing ethnic groups in the United States . Latinos face numerous adversities that heighten their risk of substance use and have seen the most growth in marijuana use across ethnicities in the U.S. , further indicating the need to understand and target misconceptions within these communities.There is a paucity of evidence, and particularly quantitative data, on the beliefs about marijuana use while pregnant and breastfeeding held by community members, and particularly those residing in vulnerable and underserved communities. The aims of the present study were to address these research gaps by surveying community residents, with an emphasis on recruiting Latino, rural, and disadvantaged residents into the sample, to gather information about their beliefs regarding marijuana use by pregnant and breastfeeding women. The survey was designed to inform two primary research questions: What beliefs about the risks and benefits of marijuana use when pregnant or breastfeeding are commonly held by adults representing these rural and vulnerable populations? And How do these beliefs vary as a function of gender, ethnicity, marijuana use, and parental status? While the study aims are primarily exploratory, we made general predictions based on prior findings of social group differences in marijuana risk perceptions, substance use beliefs, or health risk perceptions more generally.

We predicted that risk beliefs would be lower and benefits beliefs would be higher for participants who had ever used marijuana and who had used marijuana in the past six months relative to those who had not ; participants who were not of Latino ethnicity relative to Latino participants ; male relative to female participants ; and participants who were not parents relative to parents .A network of 8 promotores de salud and 20 research assistants were trained to recruit and administer the survey to residents from counties within the San Joaquin Valley, California. The promotores network enhanced opportunities to recruit “hard to reach” community members, including those who reside in isolated geographic regions. Spanish-speaking promotores and research assistants provided Spanish versions of the survey to those who preferred it. The Spanish surveys were translated and back-translated by trained translators and then validated through focus groups with Spanish-speaking promotores. Promotores and research assistants recruited residents attending local events , community organizations , organizations serving parents , and home visits by promotores to community clients. Data collection took place between April 2019 and November 2019. Promotores and research assistants distributed informational fyers inviting adults aged 18 and older to participate in a 15–20-min survey about their views on marijuana use during pregnancy and breastfeeding. Participants who could not read or write in English or Spanish were offered the opportunity to have it read to them; three participants completed the survey in this manner. Upon completion, participants received debriefng information and a $20 gift card in a Table 2 presents rates of agreement with statements about benefits and risks of marijuana use while pregnant or breastfeeding for the total sample. A slight majority were either neutral about or agreed with the statement that using marijuana while pregnant helps to reduce pain and discomfort whereas 49% disagreed with this statement. In contrast, a strong majority of participants disagreed that marijuana use during pregnancy helps to reduce depression, has no lasting harms for the baby, is safe because it is plant-based and natural, and helps to reduce morning sickness and nausea.

Over 60% of participants agreed that use during pregnancy poses risks to the baby including attention and learning difficulties, lowered IQ, THC addiction, behavioral problems, brain damage, preterm birth, low birth weight,mobile vertical rack and pregnancy complications. Proportions who were neutral or disagreed with these statements ranged from 29.0% for risk of behavioral problems to 39.0% for risks of preterm birth and low birth weight. Comparable patterns of agreement emerged for beliefs about use while breastfeeding. A slight majority were neutral about or agreed that it helps to reduce pain and discomfort whereas a majority disagreed with the other five statements about benefits. Proportions of participants who were neutral or agreed with these five statements ranged from 24.7% for use helps calm the baby to 44.2% for use helps reduce depression. Over 60% agreed that use while breastfeeding poses risks to the baby including attention and learning difficulties, lowered IQ, THC addiction, behavioral problems, and brain damage. Proportions of participants who were neutral or disagreed with these statements ranged from 29.0% for risk of attention and learning difficulties to 31.9% for risk of brain damage. In response to items assessing beliefs about the presence and effects of THC in breast milk, 65.6% of participants believed that THC passes to the baby and has negative effects on the baby whereas 21.0% believed it passes to the baby and has positive effects on the baby and 13.4% believed that none to some THC passes to the baby and has no effect on the baby. Only 20% of participants gave the most scientifically accurate response that THC lasts in breast milk for 6 days to 2 weeks; 42% believed it lasts 0 h to 2 days and 37.3% believed it stayed in breast milk permanently.We used χ2 tests to determine differences in agreement with potential risks and benefits of marijuana use during pregnancy and breastfeeding as a function of marijuana use, Latino ethnicity, gender, and parental status. Table 3 presents the proportions of agreement with benefits and risk statements by participants who had ever versus never used marijuana. As predicted, those who had ever used marijuana were significantly more likely to be neutral about or agree with all statements about potential benefits of marijuana use while pregnant or breastfeeding, and to be neutral about or disagree with all statements about potential health risks of marijuana use while pregnant or breastfeeding. Analyses of differences between participants who had used marijuana in the past 6 months and those who had not revealed similar patterns of group differences.

Those who had used marijuana in the past 6 months reported higher agreement with all benefits statements and lower agreement with all risk statements for marijuana use in pregnancy and while breastfeeding . Latino and non-Latino participants were generally comparable in their agreement about benefits and risks of marijuana use while pregnant and breastfeeding, with the following exceptions in which, as predicted, Latino participants reported relatively more health-cautious beliefs . Fewer Latino than non-Latino respondents endorsed the beliefs that marijuana use during pregnancy reduces pain and discomfort and that it reduces morning sickness and nausea, and more Latino than non-Latino respondents agreed that use could lower a child’s IQ. For statements about marijuana use while breastfeeding, fewer Latino than non-Latino respondents were neutral about or agreed that it helps calm the baby and more Latino than non-Latino respondents believed that use increases the risk of attention and learning difficulties.In terms of gender differences, predictions that benefits beliefs would be higher and risk beliefs would be lower for male than female respondents were supported for 10 of the 24 beliefs . More males than females agreed that marijuana use during pregnancy reduces pain and discomfort whereas more females than males agreed that marijuana use during pregnancy increases the risks of preterm birth and low birth weight. With respect to marijuana use during breastfeeding, more males than females agreed that it helps to reduce pain and depression, poses no lasting harms to the baby, is safe because marijuana is plant-based and natural, and increases a mother’s milk supply. In contrast, more females than males indicated agreement that use during breastfeeding can lead to infant THC addiction and increase the risk of behavior problems.The present study revealed distinctive patterns of beliefs about marijuana use while pregnant and breastfeeding in a sample of residents in primarily rural, Latino-majority, and disadvantaged communities in California, a state that has legalized the use of marijuana for recreational and medicinal purposes. Taken together, the levels of endorsement of beliefs about benefits of use and lack of endorsement of beliefs about risks to infant health and well-being highlight the need for public health education about risks of maternal marijuana use in these communities and identify specific beliefs and community groups to prioritize in these educational efforts. Overall, the most common beliefs regarding marijuana use both during pregnancy and while breastfeeding are that it helps to reduce pain and depression. These beliefs are not supported by empirical research. In contrast with modest support that cannabis can reduce pain for people with chronic pain conditions , evidence that it reduces pain sensitivity is inconsistent , and research on the effects of marijuana on pain during pregnancy and while breastfeeding remains lacking. For depression, the evidence base suggests that cannabis can worsen rather than improve depression and, to our knowledge, no studies have tested its impact on depressive symptoms for pregnant and breastfeeding women. Almost 30% of participants reported neutral or positive beliefs that marijuana reduces nausea during pregnancy, another belief that is not empirically supported. Although some evidence suggests that cannabis can aid in pain relief and nausea in cancer patients , it is also positively linked with episodes of nausea and vomiting in cancer patients and the general public . Despite perceptions that cannabis reduces nausea during pregnancy and prevalent advice from cannabis dispensaries to use cannabis to alleviate pregnancy-related nausea , evidence remains lacking. In addition to the substantial endorsement of beliefs that use provides symptom relief for maternal users, up to 25% of participants were neutral about or agreed that it is safe because it is plant-based and natural and that it poses no lasting harms to the infant. Beliefs that use while breastfeeding helps calm the baby received the least endorsement, suggesting that it might be given lower priority in health communications and guidelines. Overall, these survey results are consistent with qualitative findings of benefit beliefs held by pregnant women and demonstrate that they are shared by community members more generally.

SWM task reaction time and accuracy data were collected during scanning and composite scores were calculated to provide a single, comprehensive measure of performance and use fewer degrees of freedom in analyses, providing more statistical power . Reaction-time data and accuracy measures were converted into z-scores, and reaction-time z-scores were subtracted from accuracy z-scores to compute the performance composite score. Using this approach, high accuracy would result in a high positive z-score, while low reaction time, which is better, would result in a high negative zscore. Therefore subtraction of the negative reaction time z-score from the positive accuracy zscore would yield a positive index indicating high overall performance Imaging Data. Imaging data from each teen were processed as in our prior studies using Analysis of Functional NeuroImages . Time series data were corrected for motion. Number of removed repetitions and average movement in each direction throughout the task were examined in relation to group, task, and interactions using correlational analyses. The average percent of repetitions removed for excessive motion during the task was 8%, resulting in 92% retained for analyses. There were no significant differences between groups in bulk motion in any of the six movement directions . The average rotational movement throughout the task for MJ users was 0.04, 0.14, and 0.05 degrees for roll, pitch, and yaw, respectively. In controls the average rotational movement throughout the task was 0.07, 0.13, and 0.06 degrees for roll, pitch, and yaw, respectively. Among MJ users, the average translational movement was 0.11, 0.05, and 0.08 mm for superior, left, and posterior, respectively; the average translational movement of controls was 0.14, 0.06, and 0.07 mm for superior, left, and posterior, respectively. There was a significant group difference in the roll direction = 2.35, p = 0.03, although such movements were quite small. Next,grow cannabis fMRI data were deconvolved with a reference function that coded the hypothesized BOLD signal for each task condition .

Controlling for linear trends, spin history effects, and delays in hemodynamic response, we computed for each brain voxel a fit coefficient that represented the relationship between the observed and hypothesized signal change for contrasts between SWM and vigilance conditions . These functional datasets were warped into standard space , resampled into 3 mm3 voxels and smoothed with a 5 mm Gaussian filter. Statistical Analyses. Regression analyses determined the variability in brain response accounted for by group, task performance, and their interaction. These group level analyses were performed in each voxel of the brain and examined the BOLD response contrast between SWM and vigilance. To control for Type I error, we only interpreted significant effects in clusters of 50 contiguous significant voxels , yielding an overall clusterwise α = .05, determined by Monte Carlo simulations . Exploratory follow-up regression analyses were performed to determine the nature of the group by performance interaction. A main effect of group revealed that marijuana users showed significantly greater activation than controls in a cluster encompassing the right basal ganglia, as well as in a second cluster encompassing the right precuneus, postcentral gyrus, and superior parietal lobule 7) and in the left precuneus and superior parietal lobule . There was no region in which marijuana users demonstrated reduced activation compared to controls . Across all subjects, both users and controls, behavioral performance data positively predicted activation in seven clusters : right middle temporal gyrus, parahippocampal gyrus, and inferior temporal gyrus; right cerebellar tonsil; right inferior parietal lobule, supramarginal gyrus, angular gyrus, and middle temporal gyrus; left middle temporal gyrus and superior temporal gyrus; left middle occipital gyrus, middle temporal gyrus, and inferior temporal gyrus; right middle frontal gyrus; and left middle frontal gyrus and inferior frontal gyrus. There were no regions in which performance was negatively associated with brain response .

A group by performance interaction was found in five clusters : left superior temporal lobule, left superior temporal gyrus and left middle temporal gyrus; right temporal gyrus and right uncus; left anterior cingulate; left uncus and left parahippocampal gyrus; and right thalamus and right pulvinar. However, findings were re-examined using movement as a covariate, and all findings remained unchanged . Performance and BOLD response data were checked for outliers, and none were found. Cases appearing as possible outliers on scatter plots were removed and analyses were redone; results remained unchanged. Both groups were checked for outliers on mood measures; although neither group contained an outlier on the BDI, the marijuana group contained one outlier on the Hamilton Anxiety Rating Scale. Analyses were re-run excluding this subject and results remained unchanged.This study examined the association between behavioral performance and brain response during a SWM task among 16- to 18-year-old marijuana users and controls after 28 days of abstinence. Results suggest that, in general, marijuana-using teens performed similarly on SWM than controls, perhaps due to the low difficulty level of the task , which approached ceiling effects. This has been observed in fMRI studies of SWM in adult marijuana users . However, specific localization and intensity of response varied between the MJ users and controls, with MJ users showing more performance-related activation in certain regions and less in others. These differential patterns emerged despite similar overall task performance across groups, suggesting an alternate relationship between task performance and brain activity among marijuana users. MJ users showed significantly more activation than controls in the right basal ganglia, an area associated with skill learning . Since the subjects were only allowed to practice the task once before entering the scanner, it is possible that the MJ users were still in the skill learning process during imaging.

The other two clusters, which were significantly more activated in marijuana users than controls, were the right and left parietal lobes. Bilateral parietal regions have been implicated in attention, spatial perception, imagery, working memory, special encoding, episodic retrieval, skill learning monitoring, organization, and planning during working memory . It is possible that there is compensatory neural effort in these areas, as observed in SWM studies of adult marijuana users . The performance data positively related to activation in several areas, and did not negatively associate with brain response in any region. Performance was positively associated with activation in the left and right temporal regions, which are associated with verbal mechanisms and episodic, nonverbal working memory and retrieval, respectively . This suggests that good task performance may be related to using multiple memory modalities. High-scorers showed more activation in the bilateral prefrontal and bilateral parietal regions that have been shown to activate during SWM tasks in youths . The performance by group interactions were the focus of this study and yielded the most interesting results. In particular,indoor cannabis grow system an interaction in the left superior temporal gyrus suggested a positive association in the users and a negative association in the controls. This may imply that the MJ users used more of a verbal strategy to achieve high task performance scores than the controls. This is interesting when considering the previous findings of deficits in verbal learning and IQ in marijuana using adolescents compared to controls . Furthermore, the right superior temporal gyrus showed an interaction where users had a negative association and controls had a positive association. Previous studies have shown this area to be involved in poorer recognition of previously seen words . This would support the notion that users are relying on a verbal strategy so that better performance linked to a decrease in activation in the right superior temporal gyrus. Moreover, an interaction in the right thalamus and pulvinar showed a negative association in the users and a positive association in the controls. These sub-cortical structures have shown an association with spatial neglect when damaged . It is interesting that these areas have a negative association in users and a positive association in controls, and may suggest that marijuana users utilize less spatial strategies than controls. The nature of the interaction revealed a positive association in marijuana users and a negative association in controls in the left anterior cingulate. This region has been linked to attention, decision-making, cue response, and response monitoring . It may be that good performing marijuana users are making a more conscious decision to react to task cues than controls, who may be reacting more automatically. The left parahippocampal gyrus demonstrated an interaction of negative association in marijuana users and positive association for controls. This region is involved in working memory and is recruited when the temporal lobe is not in use . Since marijuana users are using more energy in the left temporal lobe as their performance increases, higher scoring subjects may rely less on the parahippocampal gyrus. The distinct interactions viewed in these different areas of the brain can mean that different systems are at work, and as one part of a system decreases in action, the other area of the system increases in activation.

Previous studies suggest that subjects who do not use traditional strategies for specific tasks showed an increased extent of activation and recruitment of additional areas, specifically verbal areas, to accomplish the task . More specifically, the pattern of results suggests that marijuana users may apply a verbal strategy to the task when achieving higher scores. It is possible that this alternative way of using the brain may be less efficient; this would explain the greater overall activation in users versus controls and recruitment of other brain regions as a compensation method. A recent review also found that multiple neuroimaging studies of marijuana users pointed toward recruitment of compensatory regions as well as task-related regions to achieve task demands . A possible limitation to this study is the interpretation of a difference in fMRI activation between experimental groups. It is possible that alternative neural pathway use is more dynamic and versatile. It is unclear whether the results are an adverse effect of the marijuana use or merely a benign difference. Further studies that more carefully describe the relationships between task performance and brain response will clarify this question. Another limitation of the current study is that most marijuana users were also moderately heavy alcohol drinkers. While these participants are representative of the population of adolescent marijuana users, most of whom also consume alcohol , it is nonetheless difficult to disentangle the effects that may be related to alcohol use. Alcohol use correlated with brain response in the right thalamus and pulvinar in the current study, but results remained significant even when accounting for alcohol use, and alcohol use did not correlate to activation in any other significant regions. Our previous research identified brain response abnormalities among marijuana users above and beyond those demonstrated by users of alcohol alone , supporting the hypothesis of marijuana-specific differences in brain response, even among teens who are heavy drinkers. Future studies should attempt to clarify the differential and interactive impact of concomitant alcohol and marijuana use on brain functioning on adolescents. Furthermore, lifetime marijuana use episodes were associated with activation in the right uncus and superior temporal gyrus. Future analyses could further investigate the associations of other brain regions, as well as neuropsychological performance, with lifetime use episodes. These subtle differenced among users may provide additional insight into the mechanisms involved with prolonged abstinence from marijuana. Future studies should also focus on investigating the nature of interactions in other domains of cognition to test if other types of tasks show these patterns. If a user’s neural differences are actually a compensatory tool, then a more difficult task may overcome their compensation abilities, therefore resulting in performance deficits. In addition, a parametric manipulation of working memory load could help specify degree of compensatory activation in marijuana users compared to controls, as marijuana users may reach a limit earlier than controls. Further studies could also explore which mechanisms and strategies subjects utilize during the tasks through qualitative data investigation. Recreational marijuana commercialization is gaining momentum in the US. Among the 11 states and Washington DC that have legalized recreational marijuana since 2012, retail markets have been opened or anticipated in 10 states, where over a quarter of the US population live. The presence of recreational marijuana dispensaries increased rapidly following the commercialization. Children are at a high risk of initiating marijuana use and developing adverse consequences related to marijuana. 

A number of studies have also examined secondary changes in marijuana use following receipt of an alcohol-specific intervention. A recent integrative data analysis study indicated that alcohol BMIs may not facilitate changes in marijuana use among college students ; instead, regardless of treatment condition, college students who successfully reduced their drinking at short- and long-term follow-ups were more likely to be non-users of marijuana or reduce their marijuana use at follow-up. This complementary relationship between marijuana and alcohol use is also supported by research indicating that the risk factors for initiation and maintenance of problematic use are similar across substances . Together, these studies suggest that interventions for alcohol may lead to secondary changes in marijuana use. Consistent with this hypothesis, young adults who participated in an in-person BMIs for alcohol use in an emergency department setting reported greater decreases in marijuana use at the 6-month follow-up than those who received feedback only . Similarly, weekly marijuana users who were seeking treatment for cigarette smoking and completed a brief alcohol intervention within the context of the smoking cessation intervention, demonstrated reductions not only in heavy drinking and tobacco smoking but also in marijuana use . In the college setting, BMIs that target multiple substances have also been associated with reductions in poly-drug use . One explanation for the differential influence of alcohol interventions on marijuana use across these studies may be related to the populations examined. Thus far, alcohol interventions delivered to acute-risk populations have had an impact on marijuana use outcomes, while collectively, interventions delivered to ‘college students’ have not. However, college students are a heterogeneous population, and not all require the same level of intervention . To our knowledge, no one has examined the influence of an alcohol intervention on marijuana use when alcohol interventions are provided sequentially in the context of stepped care,cannabis drying racks in which individuals who do not respond to an initial, low-intensity level of treatment are provided a more intensive treatment .

The purpose of the current study was to examine marijuana use in the context of a stepped care intervention for alcohol use.We conducted a secondary analysis of data from a randomized clinical trial implementing stepped care with mandated college students . In this study, all participants received a brief advice session administered by a peer counselor. Participants who continued to drink in a risky manner six weeks following the BA session were randomly assigned to either BMI or AO conditions . Step 2 participants who completed the BMI as opposed to AO reported greater reductions in alcohol-related consequences at all follow-up assessments . We tested three hypotheses to examine whether interventions that reduce alcohol-related outcomes may also reduce marijuana use. First, because dual marijuana and alcohol users consume higher levels of alcohol use and experience more alcohol-related consequences , we hypothesized that marijuana users would report higher HED frequency, peak blood alcohol content , and alcohol related consequences in the 6 weeks following a BA session, after controlling for their pre-BA drinking behavior. Second, we hypothesized that heavy-drinking marijuana users who did not respond to the BA session and, therefore, were randomized to a Step 2 BMI or AO would report worse alcohol-related outcomes at 3-, 6-, and 9-month follow-ups than non-users. Third, we examined whether marijuana users changed their marijuana use frequency at any of the three assessment time points following the Step 2 BMI. Examination of marijuana use in this context will improve our understanding of whether marijuana use lessens the efficacy of alcohol interventions, even when delivered sequentially in stepped care. Furthermore, it will inform future intervention efforts aimed at reducing both alcohol and marijuana use. 2. Method 2.1. Participants and procedures Participants were 530 undergraduate students age 18 years and older who violated the campus alcohol policy at a four-year, private, liberal arts university in the Northeast . Students were referred to the student health office for mandatory counseling following adjudication by campus judicial affairs staff, agreed to participate in the study and provided informed consent. All students received Step 1, a manualized, 10 to 15-min Brief Advice session that was administered by a peer counselor .

Six weeks after the BA session, participants completed an online assessment. Higher risk students were eligible to receive the next step of care and were randomly assigned to BMI or AO . Lower-risk drinkers were not randomized to Step 2 nor were provided additional intervention, but completed follow-up assessments at 3, 6 and 9 months.Participants indicated how many times they used marijuana in the past 30 days at baseline and at each follow-up assessment time point. Because marijuana use was highly zero-inflated , and due to our interest in whether being a marijuana user influenced intervention outcomes, dichotomous variables were created to group individuals into user versus non-user for use in analyses to compare these subgroups.Alcohol use was assessed using the Alcohol and Drug Use Measure at baseline and each follow-up. To determine if participants who completed Step 1 of the intervention would also complete Step 2, participants reported the number of times they engaged in heavy episodic drinking , defined as consumption of 5+ drinks for males , in the past month. The maximum number of drinks consumed during their highest drinking event in the past month and the amount of time spent drinking during this episode were used to calculate the students’ estimated peak blood alcohol concentration using the Matthews and Miller equation and an average metabolism rate of 0.017 g/dL per hour.First, distributions of outcome variables were examined, and outliers falling three standard deviations above the mean were recoded to the highest non-outlying value plus one , resolving initial non-normality in outcomes. Demographic information and descriptive statistics for the outcome variables were calculated . To examine marijuana users’ drinking behavior following BA for alcohol misuse , multiple regression models were run to predict each alcohol outcome variable at the 6- week assessment from baseline marijuana user status , controlling for gender and the corresponding alcohol outcome assessed at baseline. To test hypotheses 2 and 3, hierarchical linear models were run in the HLM 7.01 program , using full maximum likelihood estimation. HLM is ideal for data nested within participants across time, for testing between-person effects and within-person effects on outcomes. An additional advantage of HLM is its flexibility in handling missing data at the within-person level, allowing us to retain for analysis any participant that contributed at least one follow-up assessment. We interpreted models that relied on robust standard errors in the determination of effect significance.

All intercepts and slopes were specified as random in order to account for individual variation in both mean levels of the outcomes and time-varying associations. Fully unconditional HLM models were run first in order to determine intraclass correlations for each outcome. ICCs provided information on the percentage of variation in each outcome at both the between- and within-person level. Next, three dummy coded time components were created for inclusion at Level 1. The first was coded and therefore allowed examination of the impact of effects on change in the outcome variable from baseline to the first followup, the second was coded to model the impact of effects on change in the outcome variable from baseline to the second follow-up ,cannabis grow tray and the third was coded in order to estimate the impact of effects on change in the outcome variable from the first to the third follow-up . In the context of these three dummy codes, effects on the intercept represent effects when all time effects are equal to 0 . Of note, as all participants received a BA session in the interim between the true baseline and 6-week assessment, marijuana user status at the 6-week assessment was used as the baseline for these analyses .To address hypothesis 2 , Level 2 effects for marijuana user status, treatment condition, and the interaction between marijuana user status and treatment condition were regressed on the three time components. Following recommendations of Aiken and West , prior to forming interactions, marijuana user status and treatment condition were recoded using effects coding , to remove collinearity with interaction terms so that all main effects of time could be evaluated in the context of models including interactions. To control for potential baseline group differences, we also regressed marijuana user status and treatment condition on the intercept. To address hypothesis 3 [i.e., whether treatment group impacts marijuana use frequency at any of the three follow-up time points, among those who reported marijuana use at 6-week pre-BMI assessment], at Level 2, treatment condition was regressed on the Level 1 intercept and all three time effects of marijuana use frequency. In models for both hypotheses 2 and 3, at Level 2, gender also was included as a covariate.Results of the HLM models predicting three alcohol outcomes at each follow-up by marijuana user status, treatment condition, and marijuana user status by condition interactions are displayed in Table 4. In the prediction of HED frequency, marijuana user status was associated with higher baseline HED frequency; however, being a marijuana user was not associated with more or less change in HED frequency between the pre-BMI assessment and any of the three follow-ups. There were no interactions between marijuana user status and treatment condition at any follow-up, suggesting that the BMI was not more or less effective for marijuana users. In the prediction of pBAC, marijuana user status was associated with higher pre-BMI pBAC. Additionally, those in the BMI condition had significantly lower pre-BMI pBACs. Controlling for these pre-BMI differences, being a marijuana user, treatment condition, and their interaction were all non-significantly associated with change in pBAC from pre-BMI to each of the follow-ups. In the prediction of alcohol consequences, being a marijuana user was associated with higher pre-BMI levels of consequences.

There were no significant effects of marijuana user status, treatment condition, or their interaction on change in consequences between baseline and either the 3- or the 6- month follow-ups. At the 9-month follow-up, those in the BMI reported fewer alcohol consequences1 ; however, this was not moderated by marijuana user status. Overall, these findings suggest that collapsing across treatment condition, marijuana users had heavier alcohol consumption and consequences compared to non-users at the pre-BMI assessment, but they did not increase or decrease their consumption or consequences between pre-BMI and any of the follow-ups. Additionally, marijuana users responded to the BMI similarly to non-marijuana users at each time point .The purpose of the current study was to examine whether heavy drinking marijuana users demonstrate poorer response to two different alcohol-focused interventions compared to non-users and to examine the efficacy of an alcohol-focused BMI on marijuana use frequency among marijuana users receiving stepped care for alcohol use. Our findings indicated that marijuana users and nonusers evidenced equivalent treatment responses to the alcohol-focused BA session and reported similar alcohol-related outcomes following the BMI. Consistent with prior research , the alcohol-focused BMI did not significantly reduce marijuana use frequency in comparison to the assessment-only group. In our sample, marijuana users did report higher alcohol consumption and problems at baseline/pre-BMI regardless of condition, and these differences between users and nonusers persisted over time. The findings of the current study are somewhat consistent with studies indicating that marijuana use does not decrease the efficacy of alcohol interventions . Although marijuana use did not necessarily lessen the efficacy of the BA and BMI sessions on alcohol use and consequences, regardless of condition, marijuana users reported higher levels of alcohol consumption and consequences at baseline and the pre-BMI assessment. This is especially noteworthy because dual users typically report increased consequences related to their alcohol use and may have a higher likelihood of being referred to alcohol-focused treatment or mandated to receive intervention for alcohol-related sanctions. Although heavy drinking marijuana users may demonstrate reductions in alcohol consequences following an alcohol-focused intervention , their frequency of marijuana use did not change as a result of receiving a BMI. We can posit several reasons for the participants’ continued use of marijuana, despite a decrease in alcohol-related consequences. First, the parent study found a reduction in alcohol consequences following the alcohol-focused BMI, but not a decrease in alcohol consumption.

While these studies provide compelling data about the scope of problems stemming from the co-use of these substances, a fundamental limitation of such population-level, cross-sectional studies is that they are unable to answer questions about event-level patterns of use. That is, the cross-sectional nature of these studies cannot provide information about the pattern and predictive relationship of simultaneous co-use within a given day or drug-use event, which may be especially critical to understanding the co-use of marijuana with other substances. For example, individuals report both using marijuana as a substitute for tobacco or alcohol and in a sequential/simultaneous manner to produce additive or subtractive subjective effects . It is difficult to differentiate such patterns of use unless examining event-level data. The few, recent studies that have used a fine-grained approach to study simultaneous use, while important, have limitations that may affect generalizability. A study examining event-level alcohol and marijuana co-use in adolescents did not report patterns of co-use, only the context of and consequences from simultaneous co-use . Another study that examined daily patterns of marijuana and alcohol co-use, but not cigarette use, in a predominantly male , veteran population found that moderate and heavy-drinking were more likely to occur on days which marijuana was used. Further, while individuals with AUD or comorbid AUD + CUD were more likely to drink heavily on such days, individuals with CUD were less likely to drink heavily, which the authors interpreted as supporting marijuana substitution . Lastly, Gunn et al., found that daily marijuana use was associated with greater alcohol consumption in college students, and this predictive relationship strengthened over a two-year period. However,cannabis grow equipment they did not report on tobacco use nor the influence of sex on the relationship between daily marijuana and alcohol use.

In light of the high rates of marijuana co-use with alcohol and tobacco in epidemiological studies but relatively absent data on event-level patterns of use, the goal of the present study was to examine daily patterns of alcohol, tobacco, and marijuana co- and tri-use in non-treatment seeking drinkers who report regularly using tobacco and marijuana. To our knowledge, no studies have examined the daily co-use or triuse of all three substances at the individual, event-level in the same sample. Because of the strong evidence for the co-use of all three substances, we hypothesized that use of one substance would indiscriminately increase the odds of same-day use of a second substance, and the use of two substances would subsequently increase the odds of using the third. Finally, as an exploratory aim, we examined whether sex moderated any observed daily patterns of co- or tri-use. While men tend to use marijuana, alcohol, and cigarettes earlier, heavier, more frequently, and have greater dependence rates than women , women may have more severe consequences from substance abuse and enter treatment earlier than men . Given the general dearth of event-level substance use studies, sex differences in patterns of simultaneous co-use have obviously not been well characterized. However, at the population level, men have higher rates of marijuana co-use with each alcohol and tobacco and display a more rapid escalation in the frequency of this co-administration than women . The characterization of sex differences in patterns of event-level co-use also may have important implications for understating the etiology and treatment of addiction. All study procedures were approved by the University of California, Los Angeles Institutional Review Board and conducted in accordance with the Declaration of Helsinki. The reported sample draws from baseline data collected as a part of four human laboratory studies. Three studies examined pharmacotherapies for alcohol use: naltrexone in an Asian American sample , ibudilast , and ivermectin .

The fourth study was an alcohol self administration study , resulting in a total sample of 551 participants. Each study recruited a sample of non-treatment seeking, regular drinkers from the Los Angeles area using identical recruitment methods of print and online advertisements. Interested participants completed an initial telephone screening to determine eligibility. During the telephone screening, all participants were asked to report their drinking over the past three months prior to enrollment. The drinking requirement for each study had the following inclusion criteria: naltrexone in Asian Americans – female requirement of > 4 drinks per week and male requirement of > 6 drinks per week, as well as have an Alcohol Use Disorder Identification Test score greater than 8; ibudilast and ivermectin – requirement of > 48 drinks per month and score > 1 on the CAGE questionnaire assessing for alcohol problems; self-administration – female requirement of > 7 drinks per week and male requirement of > 14 drinks per week. Age restrictions for the naltrexone and ibudilast study were between 21–55, whereas participants had to be between 21–65 for the ivermectin study and 21–45 for the self-administration study. Only two studies had ethnicity requirements. Participants in the naltrexone in Asian American study were of East Asian ethnicity and participants in the self-administration study were Caucasian. All studies shared the following exclusion criteria: 1) current involvement in treatment programs for alcohol use or having received treatment in the past 30 days; 2) use of nonprescription drugs or prescription medications for recreational purposes; 3) self-reported history of exclusionary psychiatric disorders assessed during telephone interview; 4) currently using antidepressants, mood stabilizers, sedatives, anti-anxiety medications, seizure medications, or prescription pain killers ; 5) self-reported history of contra-indicated medical conditions or any other medical condition that may interfere with study participation; 6) intense fear of needles or adverse reactions to needle puncture; and 7) if female, pregnancy, nursing, planning to get pregnant in the next 6 months or refusal to use reliable method of birth control.

Specific to the ivermectin study, participants were excluded if they had a Body Mass Index less than 18.5 or greater than 30. For the self-administration study, participants were excluded if they weighed over 265 pounds. If participants were eligible following the telephone screening, they completed an in-person screening visit where written informed consent was obtained. During the screening visit, participants were required to produce a breath alcohol concentration of 0.000 g/dl, and test negative for pregnancy and drug use, except for marijuana, on a urine toxicology screening.Participants completed a battery of measures at the screening visit. A demographics questionnaire assessed age, sex, and ethnicity. The Timeline Follow-Back queried daily alcohol consumption in standard drinks, number of cigarettes smoked per day,mobile grow system and marijuana use during the previous thirty days. Marijuana use was assessed in a dichotomous fashion ; route of marijuana administration was not recorded. Alcohol and cigarette use was assessed as a continuous variable. Use of other tobacco products, e.g. snus or chewing tobacco, was not assessed. The Fagerström Test of Nicotine Dependence queried extent of nicotine dependence. The AUDIT was administered to evaluate severity of drinking. The Cannabis Use Disorders Identification Test , a reliable and valid adaptation of the AUDIT, was given to assess marijuana use severityOf the 551 total subjects who were screened for the four studies from which we culled data, 541 reported using alcohol on the AUDIT and/or TLFB, 296 reported using marijuana on the CUDIT and/or TLFB, and 260 reported using cigarettes on the FTND. As this study aimed to understand patterns of co- and tri-use among all three substances, we included only participants who reported using alcohol, cigarettes, and marijuana on a monthly basis. This selection resulted in a final sample of N = 179 participants. While this represents a significant decrease in the number of subjects, statistical power is still quite high for these analyses. The proposed analyses test the association between drug use on a per-day basis . Thus, the sample size for this study is properly conceptualized in terms of both the number of subjects, 179, but also the number of Level 1 observations which is 5390 total days. To confirm that this study is well powered, GPower 3.1.9.2. was used to conduct a power analysis. Based on a simplified repeated measures approach, a small effect size and a nominal α = 0.05 threshold, power for this study was exceptionally high . To explore patterns of marijuana, alcohol, and/or cigarette co-use a series of multilevel logistic models were run on 30-day timeline follow-back drug use data. Owing to the one on-one clinical interview nature of data collection for the key variables, there was no missing data in this study. Only individuals who reported using all three substances at least once per month were analyzed.

Multilevel logistic modeling was chosen because the data structure is nested with days nested within subjects which is appropriately modeled with a multilevel modeling approach and the outcome variable of whether a given drug was used on a given day is binary necessitating the logistic modeling approach. Multilevel logistic models were run via PROC GLIMMIX in SAS version 9.4 with a binomial dependent variable distribution and a logit link function. Models were run with cigarette use and marijuana use as the dependent variable and the other drug classes treated as predictor variables with main effects and interactions to test for potentially synergistic effects of combined use on the likelihood on the third drug use , or a suppressive effect where use of both drugs is associated with the same risk as singular use . Variables tested were Drink, a binary Level 1 variable coding whether alcohol was consumed on a given day, Smoke, a binary Level 1 variable coding whether cigarettes were smoked on a given day, and Marijuana, a binary Level 1 variable coding whether marijuana was used on a given day. To disentangle within-person effects from between person effects , person-means for each predictor variable were entered into models as Level 2 variables. To further ensure that the effects reported are within-subject effects, all Level 1 variables were treated as random at Level 2, meaning the effects were allowed to vary between subjects. Where interactions were observed, analysis of simple slopes were conducted through a recentering scheme to test the lower-order effects at specific levels of the interacting variables. In accordance with the NIH policy on considering sex as a biological variable and given the sex differences in the prevalence of marijuana, tobacco, and alcohol use in the US , we also tested for sex differences in the propensity for drug co-use. To test the robustness of these results several covariates were explored including: age, ethnicity, and source study, all of which were included as Level 2 variables. Ethnicity was examined as a covariate because one of the source studies was completely composed of individuals of East Asian descent , and age was included due to findings that patterns of co-use may differ by age . In line with the recommendations of , where discrepancies between models which included vs. omitted covariates were observed, we report the results of both models.Please see supplemental information for summary tables of all results. To first test whether average drug use frequency across these three drugs of abuse were correlated at the subject level, a series of linear regressions were conducted analyzing the correlation between proportion of days using each drug from the TLFB. Both drinking frequency and marijuana use frequency were found to independently predict cigarette smoking frequency , but drinking frequency did not predict marijuana use frequency . While these results suggest that subjects who use cigarettes and drink alcohol more often also use marijuana more frequently, these analyses do not address the central question posed in this paper of whether use of one substance on a particular day increases the likelihood of co-use or tri-use on that same day.To test whether use of one drug increases the likelihood of same-day co-use, a series of multilevel models were run with daily use of each drug included as Level 1 variables and drug use frequency person means also included as covariates to disentangle the between subject effects summarized in 3.1 from same-day effects. such that the effect of combined use of alcohol and marijuana on a given day was sub-additive . This interaction was such that on non-drinking days, marijuana use was associated with relatively large increases in the likelihood to smoke cigarettes .

We placed flyers in marijuana dispensaries, vape shops, cafes, stores, on bulletin boards at community colleges, and on Craigslist and Facebook. We attempted to interview participants twice, in order to allow conversations to develop more deeply and to use the content of the first interview to inform questions in the second. Out of 32 enrolled participants, 24 completed the second interview. This study was approved by the University of California, San Francisco Committee on Human Research. Participants provided written informed consent. We used pseudonyms for this and all publications. Semi-structured qualitative interviews lasting 60-90 minutes were conducted between January and August 2015 by six trained interviewers. Discussion topics included definitions of smoking, experiences with tobacco, e-cigarettes, marijuana, marijuana vaporizers, and other products. To further generate discussion of comparative harms and benefits of products, participants were asked to arrange labeled pictures of various products from the least harmful to the most harmful and talk through their sort process.We audio recorded and professionally transcribed the interviews and coded transcripts using Dedoose software. LP and SS independently blind-coded and compared a sub-set of transcripts to develop the study’s coding guidelines. We created code definitions, developed a consistent coding scheme and discussed the coding results to ensure codes were applied consistently. SS coded the larger set of remaining transcripts. Given the emerging nature of the legalized marijuana market and the lack of existing research in this context, ebb and flow trays we adopted a thematic analysis approach that would allow us to discover emerging behaviors and meaningful categories for our participants and to generate themes iteratively during review of coded transcripts.

All authors reviewed memos with illustrative quotes summarizing each theme and discussed themes iteratively to reach consensus and theme saturation. Participants primarily evaluated products along five dimensions: whether or not the product was combusted, potency of the psychoactive agent delivered, presence of unnatural chemicals, addictiveness, and source of information about the product. Participants generally assessed harms in the context of perceived benefits, and frequently discussed alternative products delivering similar benefits, but with less harm. They gauged harms in nuanced ways, with criteria for judging harm differing between tobacco and marijuana products and comparing them with alcohol, illicit drugs, and pharmaceuticals. Participants commented on the addictive nature of tobacco compared to alcohol, opiates, and prescription drugs. In contrast, participants spoke about the habitual urges to use marijuana but rarely reported physiological withdrawal symptoms. Several participants also explicitly mentioned physiological changes in the body associated with addiction to marijuana. ‘Ben’, age 22, commented, “I feel that for a lot of people, especially in Colorado, it’s very much emotionally dependent, mentally dependent, on marijuana…Over a chronic period of [using] it, your body adjusts and lowers the blood flow to your cerebellum so that when you smoke, you have normal flow.” Some, like ‘Brad’, age 25, acknowledged that they “need [marijuana] to function.” Some participants discussed addiction to marijuana as affinity for euphoria or the positive feelings associated with getting high. Thus, it was the psychological benefits of marijuana that were viewed as addictive. When asked what the addictive component in marijuana is, ‘Owen’, age 20, said, “Euphoric feeling;” an observation confirmed among several other participants. Participants did not generally identify tolerance as a sign of addiction. Instead, some marijuana users discussed high potency products as a useful way to overcome tolerance and reclaim positive effects. Participants also discussed tolerance increasing with use; some temporarily stopped use for a few days or weeks to bring their tolerance level down in order to be able to better feel the effects of marijuana when using smaller doses or less concentrated products.

The ability to abstain from use without physical withdrawal validated for some participants that marijuana was not addictive. As ‘Erin’, age 24, commented, “I smoke [marijuana] because I like it, but, I don’t have to wake up in the morning and smoke a bowl like I have to wake up in the morning and smoke a cigarette. I’ve gone periods of time without smoking marijuana, and you can quit like that. I don’t feel like it has the addictive properties that cigarettes have.” Because of its perceived naturalness, marijuana was also believed to be superior for therapeutic functions to pharmaceutical “pills” , which were perceived as more addictive. Informational sources mentioned by participants can be broadly classified as external and internal . Participants described information from governmental agencies as exclusively concerning harms of products, and mostly related to tobacco use. Participants reported seeing warning labels on tobacco products, which was particularly salient to ‘Rashawn’, age 24, who had lost his grandmother to tobacco-related illness. As he explained, “my friends wanted to do [blunt wraps]…but I looked at them and it has this warning. … and I thought that was just for cigarettes. I wasn’t really prepared to have a warning of cancer on the blunt wrap. I was like, so you guys see this? … I’m not okay with it. I could possibly have cancer because my grandmother, she’s my favorite person in the world, she died of lung cancer.” While several participants explicitly referenced media campaigns when discussing tobacco related harms , it was less common for participants to cite health authorities as sources of knowledge on the harms of e-cigarettes or marijuana. Some participants noted the contradiction between government information on harms and their own experiences. ‘Sadie’, 24, shared, “My whole life I was taught that weed was really bad, and then when I smoked it, I was like, wow, this really makes me feel good. And I was depressed at the moment. And that was … the first time … I was okay.” Participants’ own bodies were a primary source of knowledge when discerning whether something was harmful or beneficial. ‘Timothy’, age 25, explained, “generally when things make you feel bad, they’re bad for you.” Similarly referencing bodily sensations, ‘Angela’, age 18, reflected, “Dabbing is really harsh on your lungs. It feels like someone is stabbing you in the lungs.” Participants often continued to use a product if their bodies did not communicate acute harms . ‘Timothy’, age 25, commented, “if I felt it affecting my lungs, then I would consider something else.” Few participants cited medical providers as a source of information about marijuana.

Employees of marijuana dispensaries and vape shops were an important source of guidance about benefits of particular products and strains. If a product yielded an unpleasant experience, retailers would recommend a different product or a lower dose rather than abstention. One of our participants, ‘Sadie’, age 24, worked at a marijuana dispensary and reported, “we have to find different strains out and what they do, how it affects people, and of course it affects people in a different way… if it’s an upper, a downer, if it’s a mellow one…” In sum, among our participants, retailers served as a source of information on product selection and customization, but not on potential harms. Our participants judged the harms and benefits of various tobacco and marijuana products along the dimensions of combustion, potency, presence of chemicals, potential addictiveness,4×8 flood tray and sources of knowledge. The narrative that non-combustible products are safer appears in the scientific literature, tobacco industry statements, and documents from regulatory agencies. While some participants recognized that smoking anything – tobacco or marijuana – was dangerous, more often combusted marijuana was perceived as safer because it was seen as having fewer chemicals and lower potency. Our findings complement the small literature on the comparative perceptions of harm of various tobacco and marijuana products, where perceptions of risk were lowest for marijuana flower. Our study enriches previous research by examining the reasons behind differential perceptions. Contrary to a previous hypothesis that marijuana flower was perceived as safer than marijuana concentrates because it was less addictive, few participants in our study considered the dependence risks of marijuana concentrates, but viewed them as a way to overcome increased tolerance. Perceived harm of marijuana concentrates was due in part to immediate adverse psychological effects, such as panic attacks. Chemicals were commonly perceived as harmful, particularly when used to manufacture tobacco or process marijuana into concentrates. Few participants associated harm with chemicals that naturally occur in tobacco or marijuana plants, thus perceiving “natural” tobacco products, such as Natural American Spirit cigarettes as less harmful, which may be unintentionally reinforced by national media campaigns educating youth about chemicals added to tobacco.

Participants utilized distinct sources of knowledge to evaluate the harms and benefits of tobacco and marijuana products. Anti-tobacco campaigns informed tobacco-related harm perceptions, whereas few public education campaigns informed perceptions of marijuana and e-cigarettes. Unpleasant personal experiences with marijuana intoxication were mentioned as potential harms more often than marijuana-related diseases or addiction, which might reflect a lack of information from government agencies on the health risks of marijuana and e-cigarettes. Even though the Colorado public awareness campaign ‘Good To Know’ publicized risks of highly potent marijuana edibles, our participants were experienced marijuana users, which may explain why no participants discussed how retailers had warned them to “go slow” with initial marijuana use. The findings from our study with a small convenience sample limited in age and geographically to young adults in Denver, CO, may not be generalizable. However, they point to issues worthy of future exploration and, together with other tobacco research, have implications for health education and product labeling. Educational campaigns about tobacco and marijuana products may be more relevant to young adults if they include diverse messages reflecting multiple dimensions of harms and benefits of tobacco and marijuana. Some aspects of tobacco harm might be relevant to marijuana, such as the dangers of marijuana combustion, as marijuana smoke impairs vascular function in ways similar to tobacco smoke. The harms of secondhand tobacco smoke exposure has been an effective theme in tobacco prevention and control media campaigns. However, educational messages that focus solely on dangers of combustion may be missing important nuances in how young people understand tobacco and marijuana related harms. Young adults in our study reported that they would rather smoke marijuana than use edibles, primarily because edibles were seen as more potent and more difficult to titrate dosage. While additional research is needed to ensure the generalizability of these findings, this study suggests that the availability of lower dose marijuana edibles may mitigate the tendency for users to choose combustible over edible products due to potency concerns. Our study also identified little awareness that there are harmful, naturally-occurring chemicals in tobacco in addition to chemicals added by manufacturers. This may be an opportunity for tobacco education that is also relevant to marijuana and e-cigarettes. These messages should be carefully tested to ensure they do not unintentionally encourage the belief that tobacco chemicals are harmless because they are natural. Studies are needed to determine how reduced risk perceptions of organic plant matter, whether tobacco or marijuana, impact use and prevalence among young people, and what education messages would address these misperceptions. Our findings suggest that messages using the words “addiction” or “dependence” may not resonate with young adults, particularly with respect to marijuana. Messages about tolerance or dose escalation may be the dimensions of addiction most relevant to marijuana users. Illustrating physical changes in the body or the brain as a result of long-term marijuana use may also aid understanding that marijuana dependence has physiological in addition to psychological risks. Stories from young users who have difficulty controlling their use would be worth exploring, similar to how the FDA’s Real Cost Campaign focused on “loss of control” as the relevant dimension of nicotine addiction. Future studies should evaluate these messages with larger representative samples. Additional research on the addictive qualities of marijuana and which demographics are particularly susceptible to these qualities is also needed. Medical professionals have important opportunities to educate patients about health risks of tobacco and marijuana use when screening for substance use. Recommendations will need to be updated continuously to address new products and delivery systems and provide guidance for medical professionals in this arena. Our finding that marketing describing products as “natural”, “pure”, “clean”, “additive-free”, or “organic” may increase product appeal or reduce perceived harm is in line with other studies. Taken together, these findings indicate the need for regulatory agencies to prohibit the use of such terms on tobacco and marijuana products .

Halfway through the focus group interview, participants were asked to reflect on the reasons behind elevated marijuana mis-use rates amongst youth high school students of color as well as what they believe unstable community indicator examples are for the prevalence of marijuana mis-use in South Central LA. As participants described their experiences visiting or not visiting marijuana dispensaries in their community as well as elucidated their line of reasoning behind why students of color have recently gained more access to marijuana, this substantial theme arose: marijuana mis-use amongst youth and adults of color within South Central LA have augmented due to increased marijuana accessibility and increase in the presence of marijuana outlets. In extricating this theme, it was discovered that the theme paralleled the research question initially posited which was “Do marginalized communities of color such as African American and Latinx communities experience more marijuana use due the presence of unstable community indicators such as marijuana dispensary abundance near schools and lacking communal forums that respond to marijuana mis-use prevention advocacy?” The development of this theme not only fit in Burnard’s open coding interview transcription analysis, but also affiliated with Dornfield’s live coding process of qualitative interview responses. Specifically, Stage 1 to Stage 10 sections were added to participant response transcription corresponding to this particular theme, mobile vertical rack however, I incorporated the live coding process due to the theme reinforcing the main research question. The live coding process included finding “main ideas” within the transcription that contained the same keywords as the research question.

Subsequently, a list of codes were grouped into categories which converged to form this theme. Under Burnard’s stages of transcriptional analysis, theterminology “dross” was applied to the transcript in cutting out unnecessary words that act as filler or deviate from the central idea of the statements relating to marijuana outlet abundance and accessibility within the transcript which constituted data refinement. In applying dross to the transcriptions, two subheadings developed which were “increased accessibility and outlet/dispensary increase.” When more transcripts were added under these subheadings, the theme expanded to marijuana outlet concentrations in urban areas due to cultural promotion and medicinal recreation popularity. The following data residing under the subheading of marijuana accessibility supports this theme. Diana stated that “All over, you see the big billboards and marijuana can be delivered to your home.” Maria stated that “you can use marijuana for medicinal purposes in the fact these uses are so it’s so easy to get permission for.” Soriyah stated that “They seek marijuana as well and that for medical reasons, but I also think they do it for enjoyment also.” Additionally, data was recorded which aligned with the subheading of marijuana outlet/dispensary increase which further corroborated the theme development. Janice stated that “I live fairly close to Western Avenue and Crenshaw and I see all these green pluses, I used to think they were churches.But as far as outlets and dispensaries, I’m assuming I once upon a time I saw one look like a beautiful department store up near Melrose. And so someone you know, jokingly asked me if I wanted to go shopping.” Diana stated that “I do know a few people that go to the dispensaries. And I have actually gone into the one on Melrose. It’s huge, and it’s amazing to see all of the stuff that’s in there. I don’t smoke marijuana. But I used to.” Lastly, Monica stated that “Marijuana was heavily regulated here in the Inland Empire almost to death. Until you know, folks started seeing the potential to make money and then they opened it up, but I do see it in more urbanized areas of the Inland Empire as opposed to like Redlands, I don’t know very many in Redlands.

So if I look in the geographical areas, they’llBased on the advancement of the focus group interview, the next theme devised was perceptions on current marijuana mis-use prevention education measures, connecting to the “effectiveness of educational tools in redirecting individuals to marijuana use recovery programs” component of the topic. Similar to the development of the aforementioned themes, a combination of Burnard’s interview transcript analysis and Dornfeld’s live coding analysis was utilized to extract keywords and splice these keywords into subheadings. Major subheadings included “participants have never heard of recovery programs through education” and “participants have never heard of recovery programs through visuals” as well as substantiated the theme. First, data was collected and placed into the “participants have never heard of recovery programs through education” subheading. Examples of this data included the following. Diana stated “And matter of fact, when you’re saying that they had some types of rehabilitation. I was like, Wow, no, that’s good. But that was the first time I had ever heard of it.” Elena stated that “So you really have to seek and then even, you know, at the doctor’s offices, they don’t say too much about it. So it will be very hard if you know, if you don’t know anyone to kind of find out about it, because it’s not something that’s just made readily available and unheard of often in our community.” Soriyah stated that “Okay. I don’t know of any. I’m just saying that there’s not a lot of messaging on it because it’s not seen as a problem.” Mikayla stated that “No one thinks there’s anything wrong with marijuana use. So no, I haven’t seen any programming for it.” Under the “participants have never heard of recovery programs through education” subheading, the following data was collected. Elena stated that “Oh, no, I haven’t been aware of these types of programming. I’ve seen posters, but they’ve been mostly for mental illness.” Monica stated that “I haven’t even seen any posters regarding marijuana mis-use recovery.” The data collected under these respective sub-headings corroborate the theme in that these responses explore whether the presence of educational curriculum have made individuals aware of these slightly obscure marijuana mis-use recovery programs and showcase participant reactions on the availability of marijuana mis-use education/programming tools within their community.

The last theme created in parallel with Burnard’s stages of transcription was that “participants believed that education on this marijuana mis-use is missing in communities now, but there are other community development tools which can reduce the prevalence of marijuana mis-use by safely steering users to treatment options or recovery programs.” Two subheadings resided under this theme, but equally linked the theme with the research topic. The two subheadings formed were “participants believed that there should be presentations/educational curriculum targeted towards elementary/middle school students” and “participants believed that community programming development would be effective in underscoring the implications of marijuana mis-use.” The data collected for the first subheading not only substantiated the theme development,vertical grow table but also the research topic sub-component of proposing stable community indicators in communities for creating community/youth awareness on marijuana mis-use. Data included quote transcriptions from 3 out of the 8 participants. Janice stated that “The education curriculum. I just think that it has to be started at a young age because they need to know about it because it’s everywhere.” Elena stated that “I also agree about starting at a younger age, I typically work with youth at a high school age. But I also think that elementary school is where you start because when they go to middle school, they have the pressures of trying to fit in. So I also think that it will help people and direct people towards prevention and treatment resources.” Jared stated that “Education is useful, young users tend to err on the side to focus on what is perceived as benefits.” Under the second sub-heading, a salient quote was extracted from Jared which was “creating maybe some drama classes, music, and art and stuff like that for youth” are great examples of effective educational tools for youth.” The theme encapsulates both data sets within respective sub-headings in that participants acknowledged gaps in effective educational tools tailored towards marijuana mis-use prevention and proposed ways in which marijuana mis-use education can be engaging for youth of color. As aforementioned, the research question was “What are the contributing causes for increases in marijuana mis-use amongst adolescents within communities of color? Have communities within South Central LA purported effective educational programming/community tools which spurs awareness of these topics and creates platforms for marijuana mis-use prevention advocacy, especially for youth of color?” Focus group methodology and program evaluation were included in the data collection tools to address these questions. When the marijuana mis-use presentation was given prior to the focus group interview, participants expressed that they were either unaware or aware of statistics that alluded to higher marijuana mis-use rates amongst high school youth communities of color. This suggests that there is a general lack of educational programming in the form of presentation and statistical information dissemination for marijuana mis-use within South Central LA.

The underdevelopment of these resources represent a unstable community indicator which indirectly fosters acceptability, subsequent consumption of marijuana, and mis-use within youth communities of color. Corroborated by Goldstick’s argument about the presence of socially disorganized communities as well as these communities formation of unstable organizational behaviors may be categorized as a social disorganization factor which drives maladaptive social/organizational behaviors including marijuana mis-use over consumption rates in South Central LA as well as individual investment in marijuana outlets to further promote unsafe messages on marijuana mis-use impacts on short/long term health. This connection between findings and Goldstick’s argument, addresses the primary research question in that the lack of educational programming was discussed in association with reflections on marijuana mis-use rates as well as a solicitation for increased education development to reverse the marijuana outlet development/misuse behaviors was established. Additionally, during the focus group discussion, all respondents relayed their own experiences as well as affirmed the abundance of marijuana outlets near high schools/urban areas such as Crenshaw, Melrose, and the Redlands. With this, respondents agreed that marijuana accessibility upon legalization increased due to profuse numbers of dispensaries near high schools/urban areas as well as stated that the easy access to marijuana represents a contributing cause to the increase in marijuana mis-use. These experience based results tie in with the proposed problem of youth access to marijuana and implicate that respondents may have exposure to the socially disorganized indicator of marijuana outlet presence within their area of residence or county. In South Central LA, this result further highlights that the increased presence of marijuana outlets poses a threat to the well being of the youth in that marijuana becomes not only more accessible to them, but also subjects them to mis-use marijuana in the long run which can unfavorably impact their educational pathway as well as their perceptions of their own health. Similar to Goldstick’s argument regarding the construction of alcohol outlets inurban areas within Michigan which led to adolescents engaging in “poly substance use,” findings delineate that increased density of marijuana outlets alongside other social disorganization indicators such as high level of crime are noted to further foster frequent marijuana substance mis-use and detrimental “behavioral comorbidities” within adolescents. Contrera examined the correlation between presence of marijuana dispensaries as well as crime rate violence in LA and concluded that the study literature model revealed the increase in crime rates due to marijuana outlet density. This result aligns with Contreras finding in that the concentration of marijuana outlets may not only drive the execution of crime which is a social disorganization indicator, but also may influence youth of color to access marijuana alongside their demonstration of violent behaviors. Juxtaposing Lankaneu’s argument that there is no correlation between “density of marijuana outlets and frequency of marijuana use amongst adolescents in LA,” result findings alternatively suggest that individuals who resided in South Central LA witnessed a pattern of high schoolers mis-using marijuana due to increased density of marijuana outlets near schools. This finding is not only supported by Goldstick’s and Contrera’s argument, but also connects to the research which is that indicators of social disorganization such as marijuana outlet development near schools may serve as a contributing cause to increase marijuana mis-use rates amongst high school students in CA.

Additionally, longitudinal epigenetic studies will allow for the examination of the impact of interventions on epigenetic changes. For example, longitudinal examination of smoking-induced DNA methylation patterns identified dynamic and stable markers across time and also observed reversal of smoking induced methylation changes after smoking cessation. Using repeated measures of DNA methylation and marijuana use, we crosssectionally identified numerous marijuana associated epigenetic markers associated at one time point but not the other , including 6 and 10 loci associated with both recent and cumulative marijuana use at Y15 and Y20, respectively. Additionally, one stable epigenetic marker, cg05575921, was associated with both marijuana variables across the examination years with consistent effect estimates . We also performed longitudinal analyses to investigate changes in methylation and marijuana use across the examinations and identified 12 CpGs that varied with change in marijuana use, including markers in AHRR, COL11A2, and TFEB. Together, these results suggest a majority of the observed marijuana associated epigenetic associations are dynamic, although stable epigenetic patterns maybe observed with marijuana use. Furthermore, the identification of dynamic markers across time suggests both recent and cumulative marijuana use may modulate epigenetic changes differently during the aging process. A possible explanation for the observation of different CpGs, as well as biological pathways and diseases, across the time points may relate to the pharmacokinetic properties influenced by age. For example,cannabis drying rack reductions in hepatic and renal clearance can increase the bio-availability of marijuana metabolites with prolongation of its half-life and subsequently, may impact molecular and cellular processes differently by age.

Consistent with our findings, dynamic epigenetic markers are more likely to be identified compared to stable markers during longitudinal analyses. However, further studies investigating the modulatory effects of marijuana on the epigenome on different age groups may provide additional insight. Moreover, changes in marijuana use may alter DNA methylation signatures, which may serve as biomarkers to evaluate continued or ceased marijuana use. Although additional studies are needed to evaluate these markers, our findings demonstrate marijuana may induce dynamic and stable epigenetic signatures that may have utilityas biomarkers for recent and cumulative marijuana use across time. The impact of lifestyle factors and behaviors on health is complex and often involves an integrative approach to elucidate the underlying biological processes. By investigating genetic contributions to methylation markers associated with marijuana use, we identified 650 cis-meQTLs, including 56 cis-meQTLs that mapped to traits in the NHGRI-EBI GWAS Catalog. Among the mapped traits, we observed consistent terms related to immunological factors, cardiovascular traits, and brain measurements. Marijuana use has been associated with alterations in white blood cell counts, blood pressure, and brain structures. Caffeine is the most consumed psychoactive substance in the world and induces dopamine release in the nucleus accumbens, a brain structure mediating pleasure and reward processing. Analogously, marijuana exerts similar effects on the nucleus accumbens via the endocannabinoid system, suggesting the pleasure and reward of caffeine and marijuana use share the same reward center. Additionally, we identified 198 DMRs associated with recent and cumulative use of marijuana at Y15 and Y20. Among the top DMRs, several regions have previously been associated with cognitive function, psychiatric disorders, and immune function. RNF39 was the most significant DMR in two of the four analyses and has previously been associated with general cognitive function and bipolar and major depressive disorders. TRIOBP is the most significant DMR associated with recent marijuana use at Y20 and has been associated with general cognitive function, schizophrenia, and basophil count.

Similarly, SH3RF3 has been associated with general cognitive ability, schizophrenia, and eosinophilia. Lastly ZFP57 has been associated with general cognitive ability, schizophrenia, autism, and rheumatoid arthritis. In sum, these findings suggest marijuana use shares common genetic and epigenetic pathways associated with immunological factors, cognitive function, and brain structures and may regulate similar molecular mechanisms and biological processes. These insights could help lead to the development of new preventive and predictive tools for marijuana-associated health outcomes. As a psychoactive substance, marijuana may modulate pathways and diseases associated with homeostasis and health outcomes. Our pathway analysis revealed differentially methylated markers over represented in pathways associated with cellular proliferation, hormone signaling, and infection. The MAPK signaling cascades are signaling pathways that regulate cellular proliferation, differentiation, and apoptosis; studies have suggested potential therapeutic benefits of CBD on cancer treatment via these pathways. With regard to hormones, the endocannabinoid system modulates dopaminergic neurons and acute use of tetrahydrocannabinol increases dopamine release and neuron activity, whereas long-term use has been associated with diminishing of the dopamine system. THC has also been shown to modulate oxytocin and areas of the brain associated with reward and addiction behaviors. Moreover, cannabinoids have been reported to promote progression of human papillomavirus positive head and neck squamous cell carcinoma, primarily through MAPK activation. Notably, a previous genome-wide DNA methylation study of marijuana identified the latter two pathways during pathway analysis. In addition to these biological pathways, differentially methylated genes associated with marijuana use were over represented in psychiatric diseases and spasticity. Marijuana use has been associated with several psychotic disorders including schizophrenia, bipolar disorder, autism, and psychosis , as well as substance-related disorders. Additionally THC and smoked marijuana have been shown to reduce spasticity among patients with multiple sclerosis and spinal cord injuries. Additionally, connections between the top marijuana associated pathways and diseases have been previously reported. For example, abnormalities in the MAPK signaling and dopamine pathways have been associated with schizophrenia, as well as the use of oxytocin for treatment of substance related disorders.

Collectively, we identified pathways and diseases over represented with marijuana-associated methylation markers, suggesting common epigenetic regulations which could serve as potential diagnostic and therapeutic targets for these related traits. The current CARDIA study leveraged repeated methylation levels and marijuana data to examine the association of marijuana use on DNA methylation. The availability of genetic data enabled the examination of potential genetic modulation of methylation markers associated with marijuana via meQTL analyses. Moreover, compared to other countries where residents use a mixture of marijuana and tobacco, CARDIA is a US-based cohort where mixing of marijuana and tobacco is less prevalent, allowing for a more complete examination of the independent associations of marijuana and tobacco smoking on DNA methylation. This study, however, is not without limitations. Although we identified biologically relevant epigenetic loci and replicated previously reported methylation markers, we were unable to replicate our findings in an independent study, and as such, the findings presented warrant validation. Residual confounding from additional factors, e.g., use of other or co-drug use and social support,vertical grow system may partially explain the observed associations. As marijuana use was considered illegal for most yearly examinations in CARDIA, use may have been under reported. However, at each examination, marijuana use was self-reported , collected at a research site , and participants’ responses were confidential . The route of administration of marijuana can also affect the onset, intensity, and duration of the psychoactive effects, as well as organ systems. Investigations into marijuana use via other routes of administration may provide novel additional insights, including the latter, which was not present during the time points in the current study but is becoming more widely used. Additionally, this study examined acute exposure to marijuana , compared to hyperacute exposure and investigations into DNA methylation changes due to hyperacute exposure may provide further insight into the acuity of exposure on epigenetic factors. And lastly, although CARDIA is a diverse cohort, Black and White participants were sampled from four centers across the US. As such, additional studies from more diverse populations across different geographical locations will enable for better generalizability of the findings presented here.Mas biomarkers for recent and cumulative marijuana use across time. The impact of lifestyle factors and behaviors on health is complex and often involves an integrative approach to elucidate the underlying biological processes. By investigating genetic contributions to methylation markers associated with marijuana use, we identified 650 cis-meQTLs, including 56 cis-meQTLs that mapped to traits in the NHGRI-EBI GWAS Catalog. Among the mapped traits, we observed consistent terms related to immunological factors, cardiovascular traits, and brain measurements. Marijuana use has been associated with alterations in white blood cell counts, blood pressure, and brain structures. We found the most significant mapped cis-meQTL has previously been associated with coffee consumption. Caffeine is the most consumed psychoactive substance in the world and induces dopamine release in the nucleus accumbens, a brain structure mediating pleasure and reward processing. Analogously, marijuana exerts similar effects on the nucleus accumbens via the endocannabinoid system, suggesting the pleasure and reward of caffeine and marijuana use share the same reward center.

Additionally, we identified 198 DMRs associated with recent and cumulative use of marijuana at Y15 and Y20. Among the top DMRs, several regions have previously been associated with cognitive function, psychiatric disorders, and immune function. RNF39 was the most significant DMR in two of the four analyses and has previously been associated with general cognitive function and bipolar and major depressive disorder. TRIOBP is the most significant DMR associated with recent marijuana use at Y20 and has been associated with general cognitive function, schizophrenia,and basophil count. Similarly, SH3RF3 has been associated with general cognitive ability, schizophrenia, and eosinophilia. Lastly ZFP57 has been associated with general cognitive ability , schizophrenia, autism, and rheumatoid arthritis. In sum, these findings suggest marijuana use shares common genetic and epigenetic pathways associated with immunological factors, cognitive function, and brain structures and may regulate similar molecular mechanisms and biological processes. These insights could help lead to the development of new preventive and predictive tools for marijuana-associated health outcomes. As a psychoactive substance, marijuana may modulate pathways and diseases associated with homeostasis and health outcomes. Our pathway analysis revealed differentially methylated markers over represented in pathways associated with cellular proliferation, hormone signaling, and infection. The MAPK signaling cascades are signaling pathways that regulate cellular proliferation, differentiation, and apoptosis; studies have suggested potential therapeutic benefits of CBD on cancer treatment via these pathways. With regard to hormones, the endocannabinoid system modulates dopaminergic neurons and acute use of tetrahydrocannabinol increases dopamine release and neuron activity, whereas long-term use has been associated with diminishing of the dopamine system. THC has also been shown to modulate oxytocin and areas of the brain associated with reward and addiction behaviors. Moreover, cannabinoids have been reported to promote progression of human papillomavirus positive head and neck squamous cell carcinoma, primarily through MAPK activation. Notably, a previous genome-wide DNA methylation study of marijuana identified the latter two pathways during pathway analysis. In addition to these biological pathways, differentially methylated genes associated with marijuana use were over represented in psychiatric diseases and spasticity. Marijuana use has been associated with several psychotic disorders including schizophrenia, bipolar disorder, autism, and psychosis, as well as substance-related disorders . Additionally THC and smoked marijuana have been shown to reduce spasticity among patients with multiple sclerosis and spinal cord injuries. Additionally, connections between the top marijuana associated pathways and diseases have been previously reported. For example, abnormalities in the MAPK signaling and dopamine pathways have been associated with schizophrenia, as well as the use of oxytocin for treatment of substance related disorders. Collectively, we identified pathways and diseases over represented with marijuana-associated methylation markers, suggesting common epigenetic regulations which could serve as potential diagnostic and therapeutic targets for these related traits. The current CARDIA study leveraged repeated methylation levels and marijuana data to examine the association of marijuana use on DNA methylation. The availability of genetic data enabled the examination of potential genetic modulation of methylation markers associated with marijuana via meQTL analyses. Moreover, compared to other countries where residents use a mixture of marijuana and tobacco, CARDIA is a US-based cohort where mixing of marijuana and tobacco is less prevalent, allowing for a more complete examination of the independent associations of marijuana and tobacco smoking on DNA methylation. This study, however, is not without limitations. Although we identified biologically relevant epigenetic loci and replicated previously reported methylation markers, we were unable to replicate our findings in an independent study, and as such, the findings presented warrant validation. Residual confounding from additional factors, e.g., use of other or co-drug use and social support, may partially explain the observed associations.

Though more respondents provided negative evaluations of marijuana use under the condition that it was determined conclusively to be harmful, the effect was not significant . This may have been due to other considerations that outweighed the consideration of harm and led these respondents to maintain that marijuana use is all right even if it was certainly harmful to the user . As expected, respondents reported significantly different evaluations of the stealing and music issues and justified their evaluations with moral and personal reasons, respectively. Under each of the proposed conditions , stealing was consistently evaluated negatively and music was consistently evaluated positively. Similarly, results showed significant differences between judgments of the legality of these issues: All the respondents agreed with a law against stealing and none agreed with a law against purchasing music. The results mainly supported the hypothesis that judgments about marijuana use contrast with judgments about the prototypically moral and personal issues. Although respondents’ marijuana use evaluations clearly contrasted with their consistently negative evaluations of stealing, results indicated that, like their evaluations of the music items, respondents were significantly more likely to report positive evaluations of each marijuana use item . Notably, however, their positive evaluations of marijuana use were not as consistent as their evaluations of purchasing music. Whereas all respondents provided positive evaluations of the general music question ,pruning marijuana only 57% of the sample provided a positive evaluation of the general marijuana question . Respondents’ evaluations of each of the additional questions about purchasing music were likewise more consistently positive than their evaluations to the same questions posed about marijuana use.

For example, almost all evaluations of purchasing music under the common practice condition were positive, whereas responses about the acceptably of marijuana use under the common practice condition yielded only 68% positive evaluations . Similarly, though none of the respondents agreed with a law prohibiting the purchase of music, 30% agreed with a law prohibiting marijuana use. These differences suggest that, despite respondents’ significantly more favorable views toward the marijuana items than the stealing items, evaluations of the marijuana use items were not as overwhelmingly positive as they were to the music issue. This lends support to the hypothesis that marijuana is a more ambiguous social issue as compared to the purchasing music and the stealing issues that show the more consistent response patterns expected of prototypically personal and moral issues. The hypothesis is further supported by comparing findings from the items aimed at assessing criterion judgments associated with prototypical issues to similar items regarding the marijuana use issue. Results generally followed expected patterns. Significantly more respondents judged stealing as not all right 1) in general , 2) in the case that it is legal for those ages 21 and older , nor 3) if it is a commonly practiced act . Moreover, all the respondents reported that this act should be not be legal. That the significant majority of evaluations remained negative despite these added contingencies is indicative of the moral reasoning about this issue . Responses to the music items were somewhat more variable than responses to the stealing items. This was primarily due to respondents’ compliance with the legal contingencies posed. Though still significantly higher than those who reported negative or mixed evaluations of the act, fewer respondents maintained that purchasing music would be acceptable even if there was a law prohibiting the act. Some respondents did, however, disagree with the acceptability of purchasing music if there was a law prohibiting the act. These respondents typically cited legal reasons for their negative evaluations , but often also stated that such a law would be unfair or unwarranted.

These results suggest that, while most respondents thought of music-purchasing as a non-moral issue that should not be part of the conventionally regulated system , some felt that the legal prohibition of an act was enough to make the act unacceptable. Responses to the criterion judgment questions for the stealing and music issues were compared with similar questions about marijuana use and were expected to demonstrate differences. It was hypothesized, that because marijuana use is an ambiguous social issue, there would be greater variability among evaluations of this issue under the various contingencies than among evaluations of the stealing and music issues. This hypothesis was partially supported. Respondents provided a mix of positive, negative, or depends evaluations of marijuana when asked to consider whether marijuana use would be all right in the presence of a law prohibiting use, or in the absence of a law prohibiting use. This variability in evaluations contrasts with findings from the stealing and music items , which respectively showed significantly higher negative and positive evaluations despite the legal contingency conditions. This suggests that respondents’ evaluations of marijuana use were more susceptible to conditions of legality. On the other hand, respondents maintained positive evaluations of marijuana under the common practice condition posed; significantly more respondents reported that marijuana use would be all right even in places where it was not commonly practiced. Taken together, these findings suggest that the legality of marijuana showed a greater impact on their positive evaluations than did the common practice condition . A review of respondents’ justifications also provided evidence for the hypothesis that marijuana use is an ambiguous issue that contrasts with prototypically moral and personal issues, which are more consistently judged within their respective domains. As expected, evaluations of stealing were explained by references to the moral domain justifications . The music items, on the other hand, were mostly justified by references to the Personal Choice category.

Comparisons of these effects were significant; that is, the moral domain justifications were more likely than expected to be referenced for the stealing items than for the marijuana use or music item sets, and the personal domain justification was more likely to be referenced for the music items than for the marijuana use or stealing item sets. In contrast to the stealing and music items, justifications for marijuana use items showed greater heterogeneity ,trimming weed plants thereby suggesting the ambiguity of the issue. Whereas justifications for the stealing and music items were significantly more likely to reference the moral domain and the personal domain, respectively, justifications of marijuana use, were equally as likely to reference the prudential and conventional domains. These findings are generally consistent with results from previous research suggesting that adolescents report a mix of domain considerations when reasoning about marijuana or drug use . Moreover, marijuana use justifications spanned a greater number of justification categories; considerations of the medical use of marijuana, the commonality or acceptability of marijuana use practices, the system of shared expectations around use, self-imposed physical consequences related to marijuana use, and individuals’ preferences and rights to choose were all frequently referenced when reasoning about marijuana use. This is in contrast with the stealing and music items set that showed considerably higher Justice/Rights justifications and the Personal Choice justifications, respectively. Findings from the present study thus suggest that marijuana use is an ambiguous social issue that elicits multi-domain considerations. These multi-faceted considerations may in turn result in more variable judgments of this issue than of prototypical issues.Some results were inconsistent with hypothesized findings or otherwise were surprising. Overall, respondents in this sample provided a higher number positive evaluations of marijuana use across the survey’s proposed questions/conditions. Though evaluations of marijuana use were not as homogenous as they were for the stealing and music issues, that respondents provided significantly more positive evaluations of marijuana use across this item set was somewhat surprising. Respondents were expected to report greater variability in their evaluations to these items, especially to items proposing breaks from conventional norms . Respondents’ positive evaluations of marijuana use under the absence of common practice condition were particularly surprising; evaluations of marijuana use did not significantly shift in the expected direction with the introduction of this condition. While some respondents reasoned that it is important to maintain shared expectations and avoid disrespecting others by engaging in acts considered inappropriate or unacceptable in that context, the majority did not think that the absence of commonality/acceptability necessarily made the act not all right. This suggests that, for this sample of adolescents, these considerations were insufficient for a negative act evaluation. However, as discussed above, the legal status of the act did effect evaluations in the expected directions. Certain results from the harm manipulation conditions were also particularly interesting.

For the respondents who believed that marijuana use was not harmful, the hypothetical condition of the certainty of harm did not have as significant of an impact on act evaluations as expected: Responses to this item were mixed, suggesting that the certainty of harm was not enough to result in significantly higher negative act evaluations as was expected. However, it is important to note the mixed evaluations of marijuana use under the condition of certain harm did in fact contrast with respondents’ initial general evaluations of marijuana use, which was overall significantly positive. Thus, though not enough to significantly sway the response pattern in the negative direction, the mix of responses to this item does suggest that the addition of the harm condition had some degree of impact on evaluations.The present study was founded on two primary concepts from social domain theory: that some social issues are multi-faceted and that informational assumptions play an essential role in judgment formations . These concepts provide structures for understanding the process of adolescents’ reasoning about non-prototypical social issues and the bases for their judgments about these issues. The findings from this study demonstrate adolescent reasoning about ‘ambiguous’ issues, as well as the role of informational assumptions in reasoning about social issues relevant to their age group .According to social domain theory, the adolescent period is one in which individuals expand their capacity for incorporating and assimilating the myriad of facets that may be involved in a single issue . These multiple facets may be considered and weighed against one another to arrive at a judgment that accounts for the various circumstantial components of the issue: “Decision-making involves weighing and balancing different considerations and goals in particular situations. The decision making process is not bounded within a domain, but includes a coordination of different domains like morality, prudence, convention, and personal jurisdiction. A variety of judgments, which coexist across ages, are brought to bear in making decisions” . Thus, there are processes of coordinating social concepts that can take many forms depending on the time and/or circumstances in which the issue is examined and on the salience of the various facets the individual has come to associate with the issue. The results of this study suggest that there is need for further research into the coordination processes undertaken when reasoning about ambiguous issues like marijuana use. Greater understanding of how individuals coordinate the various facets of issues can offer insights into relative the salience and impact these facets have on judgments, and ultimately, behaviors. The multiple cross-domain justifications adolescents frequently provided for their evaluations, and the shifts that took place in their evaluations as various hypothetical conditions were placed on the issue, were indicative of the factors associated with issue for these respondents. It may be that these respondents balanced these considerations against one another to form a judgment. Not only did respondents often recognize and explicitly state that there were various factors that should be considered when justifying their responses, but they at times were unable to settle on a positive or negative evaluation . Moreover, their statements typically communicated that the circumstances that were posed in the contingency questions were influential to their reasoning and judgments, or were at least considered and then dismissed as less crucial to their than other relevant factors. These qualitative components of the findings may be indicative of the composition of the coordination process involved in these adolescents’ reasoning.This was suggestive of the ambiguities involved in this issue, especially as compared to their more homogenous judgments of the prototypically moral issue . As reviewed in the Introduction, Turiel et al. explain that the uncertainties of the differing assumptions associated with these non-prototypical issues gives them their ambiguous character.