Cigarettes and alcohol can have combined pharmacological effects that can result in a heightened reward , and may contribute to their co-use. Previous research found that young adults reported increased pleasure from smoking cigarettes under the influence of alcohol , which could be an important factor underlying their co-use. The relationship between frequency of binge drinking and pleasure from smoking remains unclear. We previously reported differences in tobacco use characteristics among young adults who all drank alcohol but differed in binge drinking frequency . Compared to alcohol use with no binge drinking, frequent binge drinking was associated with smoking more cigarettes per day, and greater temptations to smoke in positive affective/social situations. Other smoking characteristics, such as being a social smoker, were associated with any past month binge drinking. We also reported a high rate of cigarette smoking on days participants binge drank alcohol , suggesting that cigarettes could have greater rewarding effects when larger amounts of alcohol are consumed. For the current study, we examined the hypothesis that greater pleasure from smoking cigarettes would be found among individuals who binge drink alcohol more frequently, e.g. engage in cigarette smoking when larger amounts of alcohol are consumed.Similar to alcohol, grow cannabis use and dependence are more common among cigarette smokers compared to nonsmokers , and marijuana use is associated with greater nicotine dependence and heavier patterns of cigarette smoking among young adults .

The literature on combined effects of tobacco and marijuana suggest that shared genetic risk factors and neurobiological pathways may explain some overlap in addictive processes for the two substances . There is evidence that cannabinoid receptors may be involved in the rewarding effects of nicotine and that cannabinoid receptor agonists may increase the rewarding and reinforcing effects of nicotine . Subthreshold doses of Delta 9-tetrahydrocannabinol and nicotine in combination were found to induce a conditioned place preference in mice , suggesting possible synergistic enhancement on reward processes. Differences between cigarette smokers and nonsmokers in response to endocannabinoid modulation of reward processing in the nucleus accumbens have also been reported . Behavioral studies have pointed to additional reasons for co-using tobacco and marijuana, including to enhance the high from marijuana or to counteract certain effects of marijuana . However, to date, limited research has examined rewarding effects of marijuana and tobacco co-use. Using cross-sectional survey data, we examined extent of cigarette smoking under the influence of alcohol or marijuana and differences in perceived pleasure from cigarette smoking when drinking alcohol compared to using marijuana among cigarette smokers who used marijuana and alcohol. Hypotheses were: a similar proportion of smoking episodes would occur under the influence of alcohol and marijuana; perceived pleasure would increase from smoking when drinking alcohol and using marijuana, and not differ across substance; and perceived pleasure from alcohol would be greater with more frequent binge drinking. Perceived pleasure from smoking when drinking alcohol or when using marijuana was also compared between the cigarette smokers who used both marijuana and alcohol in the past month and cigarette smokers who only drank alcohol or only used marijuana.

Perceived pleasure experienced from smoking cigarettes when drinking alcohol or using marijuana could underlie the persistence of use over time and problems with cutting down or quitting . Given the high prevalence of co-use of cigarettes with either alcohol or marijuana and previous research suggesting that co-use is associated with greater nicotine dependence potentially undermining smoking cessation , results of this study could inform the design of specific intervention components addressing substance co-use in smoking cessation interventions for young adults.The study analyzed baseline survey data from a randomized controlled trial of English literate young adults, age 18-25, residing in the United States, who reported smoking at least 100 cigarettes in their lifetime and currently smoked at least 3 days per week. A full description of the study design and protocol is described in Ramo et al. . Because the study was designed to examine the efficacy of a Facebook smoking cessation intervention, participants also had to use Facebook at least 4 days per week. Recruitment occurred between October 2014 and August 2015 through a paid advertising campaign on Facebook. Participants were screened for eligibility online, and, if eligible, signed an online University of California Institutional Review Board approved informed consent, and sent proof of identity. Verified participants were sent the baseline survey online, assessing demographics, smoking, and other health risk behaviors, including alcohol and marijuana use. Of the 7540 respondents who passed online eligibility screening, 1039 signed online consent; 739 sent verification of identity online; and 500 completed a baseline assessment. Enrollment rates were consistent with those reported in online smoking studies . The primary analyzes for the present study used baseline data from a sub-sample of participants who reported past 30-day use of both alcohol and marijuana in addition to tobacco.

Results were also compared to cigarette smokers who only used marijuana or only drank alcohol in the past month.Demographic and substance use measures used here have previously demonstrated good reliability and validity with young adults . Sociodemographics assessed were gender, age, ethnicity, years of education, and annual household income. Participants were asked “Have you smoked at least 100 cigarettes in your life” , followed by “What is the usual number of cigarettes you smoke in a day,” and “On average, how many days in a week do you smoke cigarettes” . Participants were asked if they had consumed alcohol in the past 30 days, if “yes,” they were also asked to report how often they drank alcohol, how many standard drinks they consumed on a typical day, and on how many of the past 30 days they binge drank alcohol. Binge drinking was defined as having 4 or more alcoholic drinks for women, 5 or more alcoholic drinks for men . Marijuana use was assessed as any use in the past 30-day .Participants were asked to report “what percentage of your cigarette smoking episodes occurred under the influence of alcohol” and “does your pleasure from smoking cigarettes change when you are drinking alcohol” based on McKee et al. . These questions were adapted for marijuana.Among cigarette smokers who used marijuana and alcohol, extent of co-use and perceived pleasure from smoking cigarettes when drinking alcohol or using marijuana were compared using paired samples t-tests. Perceived pleasure from smoking cigarettes when drinking alcohol or using marijuana were each tested against the null hypothesis . Participants were also grouped based on frequency of binge drinking in the past month based on Gubner et al. . Perceived pleasure from smoking cigarettes when drinking alcohol was compared across the binge drinking groups using ANOVAs. To validate findings in the current study among cigarette smokers who used both marijuana and alcohol, results from these individuals were compared to cigarette smokers in the parent study who used only marijuana or only alcohol . Statistical analyzes were performed using SPSS22 .Among a sample of young adult cigarette smokers who used both alcohol and marijuana in the past month, a similar proportion of cigarette smoking episodes were reported under the influence of alcohol and indoor cannabis grow system. In contrast, perceived pleasure from smoking cigarettes was only reported to increase when drinking alcohol but not when using marijuana. There were no differences between smokers who used alcohol þ marijuana compared to smokers who used only marijuana or only alcohol on these measures, increasing the validity of the findings. Tobacco and alcohol have been found to have combined pharmacological effects that result in greater reward . In contrast, marijuana and cigarettes may be coused primarily for reasons other than increased pleasure. For example, nicotine may attenuate some of the cognitive impairments induced by acute or chronic marijuana use and it has been suggested that nicotine may attenuate the sedative effects of marijuana . A recent qualitative study examining the effects of cigarette smoking on the perceived effects of marijuana use found certain individuals reported smoking cigarettes to intensify the marijuana high, while others reported not liking the combined effects as it made them feel dizzy or nauseous . Combined effects of marijuana use and cigarette smoking seem to vary by user, and may not be as uniform as the combined effects of alcohol and cigarettes. Since the main route of administration for marijuana is smoking, some aspects of marijuana use may serve as cues that increase urges to smoke cigarettes . In addition certain individuals may enjoy aspects of smoking in general, regardless of substance . Previous studies have found that urges to use marijuana and tobacco were correlated among young adults and that using tobacco subsequent to marijuana is a common pattern of use . The primary route of marijuana administration is smoking, often mixed with tobacco . Route of marijuana administration could play a role in differences in perceived pleasurable effects of smoking cigarettes when using marijuana. Research is needed to compare reasons for use and effects of cigarette smoking between different routes of marijuana administration .

Both the non-binge drinkers and all binge drinking frequency groups reported an increase in perceived pleasure from smoking cigarettes when drinking alcohol, suggesting that frequency of binge drinking and binge drinking itself may not be essential to the relationship between enhanced pleasure from smoking during alcohol consumption. Greater pleasurable effects of smoking cigarettes when drinking alcohol may occur with lower levels of alcohol consumption. Alcohol has biphasic stimulant and sedative effects, and nicotine has been found to attenuate the sedative/hypnotic effects of heavy alcohol consumption . Attenuation of sedative effects may be a motivation for the co-use of tobacco and alcohol most relevant to binge drinking.There are several limitations of this work. We used retrospective self-reported data which may be biased and cannot establish a causal inference between alcohol and marijuana use and perceived pleasure from smoking cigarettes. Laboratory-based human pharmacology studies or intensive longitudinal event-level designs , are needed to replicate our findings and advance this area of research. We did not assess the overlap between cigarettes smoked when both drinking alcohol and using marijuana, mode of marijuana use , or marijuana use frequency. This last limitation is especially important, since the relationships between marijuana and tobacco use and reasons for co-use may vary as a function of frequency of use . We also focused exclusively on the enhancement of perceived pleasure of smoking cigarettes by alcohol or marijuana rather than the ability of cigarettes to enhance the pleasurable effects of other substances. Previous work by McKee et al. suggests the direction we assessed was likely to be more affected, with individuals deriving more pleasure from smoking cigarettes while drinking compared to pleasure from drinking alcohol when smoking cigarettes . It should be noted that we asked participants to distinguish pleasurable effects of smoking cigarettes from effects of other psychoactive substances they co-used and we do not know how well participants were able to reliably do this. However differences in the reported pleasurable effects of alcohol on cigarettes compared to cigarettes on alcohol suggest that individuals are able to differentiate the effects of one substance on another . Future studies might also investigate reasons for and expectancies of substance co-use in addition to perceived pleasure . Lastly, our sample comprised young adult smokers participating in a Facebook smoking cessation intervention, which may limit the generalizability of the results; however given that 90% of all US young adults use social media , this concern is limited.The United States faces a dynamic landscape regarding marijuana, opioids, and alcohol. Concerns about these substances center around opioid misuse,an ongoing high prevalence of alcohol-related harms,and the liberalization of marijuana use policies.Not surprisingly, excessive use of alcohol, marijuana, and prescription opioids increases risk of addiction and developing associated substance use disorders .In 2014, 17.0 million people 12 years of age or older were diagnosed with alcohol use disorder, 4.2 million had a marijuana use disorder, and 1.9 million had a disorder related to the non-medical use of prescription pain relievers.In recent years, heroin and other potent opioids such as fentanyl have made increasing contributions to rising opioid overdoses.In addition, persons with alcohol, marijuana, or opioid use disorder are more likely to have comorbid conditions, which worsen prognosis, contribute to poor health,and can lead to inappropriate health service use.