As expected in these models, average cigarette use, marijuana use, and alcohol use frequency were all significantly associated with likelihood to smoke cigarettes on a given day . Neither sex, age, ethnicity, nor source study were significant covariates, and their inclusion in the model had no effect on these reported outcomes. The present study was the first to examine event-level, daily patterns of co-use of marijuana, alcohol, and cigarettes in a sample of non-treatment seeking individuals. Similarly, any cigarette smoking increased the probability of same-day alcohol or marijuana co-use, and marijuana use also increased the odds of same-day alcohol or cigarette co-use. Additionally, we found generally additive effects of simultaneous co-use on the likelihood of using a third substance ; the co-use of alcohol with cigarettes and marijuana with cigarettes increased the odds of same day marijuana and alcohol use by over five times, respectively. When taken together, these results indicate that the use of either marijuana, alcohol, or tobacco substantially increases the probably of the co-use one of the two other substances, and if two of these substances are co-used, the likelihood of a using the third is further amplified. Our results may aid in the understanding of how simultaneous co-use of marijuana with alcohol and/or tobacco relates to the etiology, maintenance, and treatment of AUD, CUD, and tobacco use disorder . Our event-level findings that marijuana, alcohol, and/or cigarette use substantially increased odds of simultaneous co- and tri-use in non-treatment seeking,mobile vertical grow rack regular substance users support epidemiological data that describe highly prevalent concurrent and simultaneous couse of these three substances. The behavioral mechanisms underlying the relationship between alcohol and tobacco co-use have been well characterized and may be applicable to understanding co-use of each substance with marijuana.
As reviewed in detail elsewhere , the underlying motivation for simultaneous co-administration of alcohol and tobacco appears to be predominantly driven by cue-conditioned cross-reactivity, in which each substance elicits cue-induced craving for the other via Pavlovian conditioning, and the additive or synergistic reinforcing effects of the drugs when used in combination. The findings of the present study may suggest that individuals are simultaneously using marijuana with alcohol and/or tobacco due to similar mechanisms. Such motives for co-or tri-use would be consistent with the majority of preclinical and clinical studies examining the combined effects or patterns of co-use of marijuana with alcohol or tobacco. For example, tobacco and marijuana co-users have reported simultaneously using both substances because each drug increases craving for the other, tobacco enhances the subjective effects of marijuana, and simultaneous co-use produces additive subjective effects . Furthermore, the majority of molecular and behavioral pharmacology studies in rodents and humans suggest additive, or even synergistic, reinforcing as well as impairing effects of combined marijuana and alcohol . Interestingly, a recent study found that alcohol consumption was positively associated with being open to experiment with tobacco or marijuana co-use in different places and with different people, suggesting a contextual or social influence on couse in addition to the pharmacological factors discussed above . If the pattern of simultaneous co- and tri-use observed in this study is representative of a chronic behavior, we speculate that additive co-reinforcement and cue-cross-reactivity, as well as the likely development of cross-tolerance due to overlapping neurobiological effects , could lead to escalation of substance use to hazardous levels and underlie the development of comorbid or even trimorbid CUD, AUD, and/or TUD. This proposed progression would be consistent with epidemiological literature indicating that the simultaneous use of marijuana with tobacco or alcohol is associated with psychological and physiological harm, negative social consequences, high risk substance use, development of dependence, more severe dependence levels, and poorer treatment outcomes above and beyond both concurrent and single drug use .
Yet, there is a sizeable literature suggesting marijuana is sometimes used as a substitution for alcohol or cigarettes. Individuals who use marijuana concurrently with alcohol or tobacco report using marijuana in place of both drugs . Furthermore, cessation studies have also shown that as marijuana use declines, craving and use of alcohol or tobacco may rise, which indirectly supports a substitution pattern of use . Indeed, some have argued for marijuana to be positioned as a substitute for alcohol and other illicit drug abuse as a harm reduction strategy . Marijuana may have a superior safety profile to alcohol or tobacco , but the concept of drug substitution as a harm reduction strategy is predicated on the idea that use of the substituted drug decreases rather than increases the likelihood of target drug use. Although marijuana use strongly augmented the odds of same-day drug co-use in our sample, we also observed that the co-use of alcohol and marijuana was associated with a decrease in the odds of cigarette consumption compared with non-drinking days. One possible interpretation of this result is that individuals were substituting marijuana for cigarettes in this particular co-use event. Despite this single sub-additive result, our findings when taken as a whole suggest additive co-use effects and indicate further research of event level, simultaneous co-use in both treatment-seeking and non-treatment-seeking populations is needed before considering marijuana as a harm reduction strategy for AUD or TUD. Sex was a significant moderator of several of the observed patterns of co- and tri-use between marijuana, alcohol, and tobacco. The effect of alcohol and cigarette use independently increasing the odds of same-day marijuana co-use was stronger in men than women. This finding is broadly consistent with epidemiological data showing that men, vs. women, have higher rates of marijuana, alcohol, and cigarette use, start using these substances at a younger age,vertical grow rack use them in greater quantities, and have greater prevalence of dependence . More specifically, 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, both of which directly support the patterns of co-use observed in the present study .
Interestingly, while men had stronger relationships of single drug use predicting simultaneous marijuana co-use, women were more likely to have drug co-use turn into triuse. We observed that the odds of alcohol use after simultaneous cigarette and marijuana couse and marijuana use after cigarette and alcohol co-use were greater in women than men. An event-level pattern of tri-use such as this, i.e., with greater odds of progressing from simultaneously using two substances to co-using three substances in an event, could plausibly be related to more severe consequences from substance use in women even if they consumed less overall quantity than men. While men use marijuana, tobacco, and alcohol more heavily and have higher rates of dependence than women, women often experience more severe consequences from use. Some, but not all , studies have demonstrated that women display “telescoping” in the development of AUD and CUD. That is, while men have higher rates of the disorders, women tend to enter treatment for CUD and AUD after fewer years and quantity of use than men . Additionally, women are at greater risk for lost productivity, alcohol-induced blackouts, more severe neurocognitive impairment, brain atrophy, and a variety of physiological problems due to alcohol abuse despite drinking less and for a shorter amount of time than men . Sex differences in patterns of co- and tri-use could inform sex specific treatment and intervention of comorbid substance use disorders. However, given the exploratory nature of our comparison of sex differences and the paucity of studies that have included sex as a variable when examining event-level patterns of co-use, our sex-related results should be viewed as preliminary and are in need of replication in independent samples. As the original purpose for collecting the data that was analyzed in this manuscript was participant screening, and the analysis presented in this manuscript was ad hoc, there are several important limitations that should be considered when interpreting our results. The primary study limitation is the potential for low external validity due to the very specific composition of our sample. The recruitment goals of the four parent studies were in part to screen individuals who were regular-to-heavy-drinkers but who did not have other serious psychiatric disorders or medical conditions. Additionally, one of the parent studies only enrolled individuals of East Asian descent . The resultant sample in the present study is reflective of these parameters; that is, one with a higher than expected percentage of Asian Americans who are very hazardous drinkers, have low nicotine dependence, have borderline hazardous marijuana use, and report having no serious medical or psychiatric conditions. However, as outlined in the introduction, individuals from the general population who simultaneously co-administer alcohol, marijuana, and/or cigarettes on a regular basis would likely present with comorbid psychiatric disorders and serious health problems, and this may be especially true for treatment-seeking populations. Further, individuals of East Asian descent generally report lower alcohol consumption and have reduced risk of AUD development than other ethnicities , so it is potentially unlikely that this ethnic background would be responsible for 36% of the individuals who use alcohol, marijuana, and cigarettes in the real world. Although controlling for ethnicity in all analyses increases external validity and confidence in the presented results, it is still unclear how the presented results may generalize to both the general population of substance using adults as well as those seeking treatment for AUD, CUD, and/or TUD. Additional limitations may be related to the use of the TLFB to retrospectively assess patterns of drug co-use. When compared to same-day assessment, the use of the TLFB interview to retrospectively record drug use introduces a risk of recency bias . However, this recency effect appears to be mostly related to underreporting measurements of consumption levels rather than accuracy in dichotomously assessing whether any drug was consumed on a given day , which would mitigate any negative influence of recall bias on the present results. Also, because our standard procedures for TLFB administration was to assess marijuana use as a dichotomous “Yes/No” variable, no information was collected onthe route, formulation, or quantity of marijuana that was consumed on a given day. For example, in our data we have no ability to distinguish whether a single “hit” from a vaporizer, 30 mg of marijuana extract taken orally, or three entire blunts was consumed in a day; all could feasibly be coded identically in our dataset. Furthermore, while we do interpret the self-report of co-use within a day as simultaneous rather than concurrent use, we do not have data directly indicating that all substances were consumed during a single drug-use event. It is conceivable, albeit unlikely, that an individual would regularly use one drug in the morning and a second in the evening, for example. Yet, we believe we are warranted to interpret same-day co-use as simultaneous given prior findings indicating that poly drug users simultaneously co-administer drugs the far majority of the time and that marijuana is commonly self-reported as being used simultaneously with alcohol or tobacco . Lastly, although overall a clear strength of our study, our data only allows us to examine couse within a given day. Thus, we are unable to determine causal pathways underlying specific sequences of co-use, and future studies, for example with ecological momentary assessment methods, should examine the temporal relationship between marijuana, alcohol, and tobacco use within a given drug-use episode. Religion and spirituality play complex roles in the health of sexual minorities. For example, they may support positive coping with challenging life circumstances. However, many major religious traditions are non-affirming of same sex attractions and behaviors , thereby contributing to stigma and oppression that undermine the potential health and psychological benefits often associated with religion and spirituality. For example, one U.S. study found that exposure to religious prejudice was associated with negative health outcomes among sexual minorities, including higher levels of stress, anxiety, shame, harmful alcohol use, and more instances of experiencing physical and verbal abuse . Similarly, findings from systematic reviews and meta-analyses suggest that while some sexual minorities find social support and refuge in religious traditions, others report religious affiliation and religion as a source of stigma and stress .