Marijuana is the most frequently used drug of abuse in the United States

Frequency of marijuana use was significantly associated with race/ethnicity and age, such that participants who identified as white and who were under age 21 at the time of assessment reported more days of marijuana use. The main effect of time was not significant, indicating that days of marijuana use was stable over 3 years of observation, consistent with the descriptive statistics in Table 1. The post-legalization slope term was also not significant, indicating that the trajectory of marijuana use for the post-legalization segment of the model did not differ from the overall trajectory.Table 3 shows the final model evaluating the impact of legalization on associations between demographic variables and frequency of marijuana use over time. We found that age and racial/ethnic identity continued to predict marijuana use frequency, but that the strength of those associations did not change over time or following legalization. In contrast, we found significant interactions of sex with both time and legalization. To better understand these interactions, we removed sex from the model and evaluated associations between time, legalization, and marijuana use frequency separately for men and women. These analyses indicated that marijuana use frequency generally decreased over time for male participants , but also increased nonsignificantly following legalization . In contrast, female participants reported increasing marijuana use frequency over time overall, but with a non-signficant decrease after legalization . Examinatin of adjusted means suggested that, in both cases,hydroponic rack system the non-significant effect of legalization was a reflection of an initial post-legalization increase followed by a reversion to the previous trend of decreasing use over time for men and increasing use for women. Table 4 shows the results of the model examining substance use predictors.

There was a positive association between alcohol frequency and marijuana frequency, but this did not vary by time or after legalization. In contrast, we found that the associations between both cigarette frequency and e-cigarette frequency and marijuana frequency over time were moderated by legalization. To clarify these interactions, we removed legalization from the model and examined associations before and after legalization. These simple effects tests showed that, before legalization, there was a consistent positive association between cigarette and marijuana use frequencies that did not vary over time . However, this association declined over time following legalization . In contrast, the association between e-cigarette frequency and marijuana frequency was significant at baseline but declined over time prior to legalization . However, following legalization there was a consistent positive association betweent the two . Finally, we evaluated the extent to which the total number of days of marijuana use prior to legalization predicted days of marijuana use after legalization, and if so whether this varied by time. Age, sex, and race were included as covariates but none were significantly associated with marijuana use after legalization in this model. We found a significant main effect and interaction with time . The former indicates that those who reported more cumulative days of marijuana use prior to 2018 also reported more days of marijuana use at the first assessments they completed in 2018, while the latter indicates that this association grew stronger over subsequent observations.We set out to examine whether frequency of marijuana use changed following legalization of recreational sales in California. We also planned to test whether post-legalization trajectories of marijuana frequency would be associated with sex, age, race/ethnicity, alcohol or tobacco use, or pre-legalization marijuana frequency. We utilized a sample of young adults who were non- and never-daily cigarette smokers at the time of enrollment. This sample has multiple advantages compared with others that are available. Unlike most national datasets, we were able to evaluate change over time in a specific cohort. Additionally, assessment occurred at specific, quarterly intervals. Thus, in addition to providing more assessments within each year, it was possible to pinpoint each assessment to before or after changes in legal status. Additionally, the analytic approach allowed us to include participants who were enrolled at different points prior to legalization and thus had completed varying numbers of assessments at that point.

Contrary to our expectations, frequency of marijuana use did not change significantly after legalization, and was stable throughout three years of observation. Participants who were younger and who identified as White reported more days of marijuana use; these associations were consistent over time and did not change with legalization. Sex differences were also noted, with men reporting decreasing and women increasing marijuana use frequency over time, though this association was not significantly related to legalization. This difference is contrary to previous research suggesting greater use among men , though more recent data suggest that this discrepancy is shrinking . Our findings are consistent with evidence that use may escalate more quickly among women . Women appear to be more sensitive to the rewarding effects of cannabis use , and thus may be more vulnerable to increasing use after initiation and/or when barriers to use are reduced. We also found that associations of both cigarette and e-cigarette frequency with marijuana frequency over time were moderated by legalization. More specifically, the association between marijuana and cigarette use became weaker following legalization, while the marijuana-e-cigarette assocation showed the opposite pattern. Frequency of alcohol consumption was consistently associated with marijuana use over time and did not change with legalization. Finally, we found that those who reported more frequent marijuana use prior to legalization tended to do the same afterward, particularly at later assessment points. Although frequency of of marijuana use was associated with both cigarette and e-cigarette use, the post-legalization findings suggest that co-use of e-cigarettes and marijuana may increase when the latter is legalized. One potential explanation for this could be that many young adults perceive vaping and marijuana use as conferring little risk , in which case legalization may have removed an important barrier to use. In combination with the finding that marijuana use was more common among those under age 21, this suggests that enforcement of minimum age laws may be an important component of limiting use of both marijuana and e-cigarettes. Our finding of no overall change in marijuana frequency is consistent with reports suggesting little impact of medical marijuana laws on use in California . It is notable that we found that those who used marijuana more frequently prior to 2018 reported greater increases in use from 2018 onward.

On one hand this is encouraging in that it suggests that lighter and non-users of marijuana were not necessarily encouraged to use as a result of legalization. On the other hand, it appears that those who were already more regular users may have tended to increase consumption, potentially increasing vulnerability to the risks associated with marijuana use. In contrast to previous studies , we found participants who endorsed greater frequency of marijuana use had greater frequency of use of tobacco products. Following legalization this was particularly true for e-cigarettes. The specific mechanism for this association is uncertain,rolling benches canada but there are multiple possibilities. First, it may be that relaxing restrictions on a specific substance reduces substance-specific concerns about harm , which then generalizes to other drugs. Alternatively, the association can be explained by use of products that deliver both drugs at the same time , or newer vaporizing devices that may do so separately. It is plausible that innovations in nicotine vaping devices encourages marijuana vaping, promoting diversified marijuana product use and synergistically increasing use of both products. This is consistent with the strengthening association between marijuana and e-cigarette use frequencies postlegalization. The association could also be a reflection of contextual or environmental influences . The possibility that lessening marijuana barriers increases tobacco use is concerning given evidence that co-use is associated with psychosocial distress , health problems , nicotine dependence , and tobacco cessation failure . The present study has several limitations. It is a secondary analysis of a naturalistic study of young adult tobacco users, which limited the specificity of marijuana-related measures and may have yielded a sample with disproportionately frequent marijuana use. There is a strong need for additional studies that include outcomes beyond simply quantity, freuqency or prevalence of use . The design may limit generalizability to other young adult samples. Another limitation is reliance on self-reported substance use data, though evidence suggests self-report tends to be accurate in observational studies, given the lack of strong demand characteristics . Additionally, self-reported data include only some days during 2015–2019 and may not be representative of use during the entirety of this period. Finally, while the study captured self-reported use of marijuana and nicotine/tobacco products before and after legalized sales of recreational marijuana began in California, we did not directly evaluate access to marijuana retail outlets or other methods of product acquisition.

Estimates of recent marijuana use in HIV-seropositive individuals have ranged from 14% to 33% , which contrasts with the 2% to 9.5% prevalence estimates in the general United States population . Importantly, prevalence of daily or near daily marijuana use has steadily increased in recent years in the general United States population and in HIV+ persons . Randomized controlled trials and observational studies of HIV+ persons indicate therapeutic benefits of cannabinoids – the active components in marijuana – in reducing pain, nausea, insomnia and improving appetite and mood symptoms . However, marijuana use has been associated with decline in cognitive function . Marijuana might influence cognitive function via the actions of tetrahydrocannabidiol – the main psychoactive cannabinoid in marijuana – on cannabinoid receptor 1, located on specific brain regions including the hippocampus, cerebellum, basal ganglia, amygdala and prefrontal cortex , which are involved in cognition . Therefore, activation of CBR1 by THC in these regions could have effects on cognitive function . Not surprisingly, the associations between marijuana use and cognitive functions has received increased attention. There is convincing evidence that acute intoxication with marijuana impairs cognitive function in multiple domains including executive functioning, processing speed, attention and working memory—with the most consistent deficits found in learning and memory functions . However, whether these deficits endure past periods of intoxication , following periods of abstinence, or in the long-term is less clear. Most cannabinoids, including THC are fat soluble and are easily stored in body fat for prolonged periods of time and are slowly released back into the circulation , a property that potentially supports the hypothesis of residual effects of cannabis on cognitive function. Two meta-analytic studies have synthesized findings of studies assessing residual effects of marijuana use on cognitive function. The first study observed statistically significant negative effects of marijuana use on learning and forgetting domains, of modest effect size . The second more recent study, found small deficits in multiple domains including forgetting/retrieval, abstraction/executive function, attention, motor skills and verbal/language, but, when the analysis was limited to studies with at least 125 days of abstinence, no significant effect of marijuana on any cognitive domain was observed . Notwithstanding, majority of the literature on marijuana use and cognitive function have been cross-sectional with modest sample sizes. Furthermore, the literature among HIV+ individuals has been scant. HIV+ individuals are vulnerable to cognitive impairments via direct effects of the virus and indirect effects of comorbid conditions highly prevalent among HIV+ individuals . Cognitive function deficits are common among HIV+ individuals even with highly active antiretroviral therapy  and have been associated with medication nonadherence . Thus, any potential negative effects of marijuana on cognitive function may be more pronounced among HIV+ individuals. To date, the relatively small literature on marijuana use and cognitive function in HIV+ individuals have focused on current use . With, 29 U.S. states passing laws allowing medical and/or recreational marijuana use, and most state medical marijuana laws listing HIV/AIDS as condition that could benefit from medical marijuana , there is a need for additional evidence on the impact of marijuana use on cognitive function, including its long-term impact, and the magnitude and clinical importance of any effects. The Multicenter AIDS Cohort Study has continuously collected data on marijuana use since its inception in 1984/1985 and evaluated cognitive function for 26 years and thus represents an ideal opportunity to study the long-term effects of marijuana use on cognitive function of HIV+ individuals. The aim of the current study is to evaluate associations between current and cumulative exposure to marijuana and changes in measures of cognitive processing speed and flexibility among HIV+ and HIV-seronegative participants in the MACS.