Effect of alcohol, tobacco, and cannabis co-use on gray matter volume in heavy drinkers.

Abstract

Objective: Alcohol, tobacco, and cannabis are the three most frequently used drugs in the United States and co-use is common. Alcohol, tobacco, and cannabis use has been separately associated with altered brain structure, and alcohol and tobacco co-use results in decreases in gray matter volume. Less is known about the effect of alcohol and cannabis co-use, and alcohol, tobacco, and cannabis tri-use. Therefore, this study examined the effect of co- and tri-use on gray matter volume, a measure of brain cell density, in heavy drinkers. Method: Heavy drinkers (n = 237; 152m/85f; age = 32.52; white = 111; black = 28; Latino = 9; American Indian = 2; Pacific Islander = 4; Asian = 59; mixed = 15; other = 9) were classified into four groups based on their alcohol, tobacco, and cannabis use: alcohol only users (n = 70), alcohol and tobacco co-users (n = 90), alcohol and cannabis co-users (n = 35), and alcohol, tobacco, and cannabis tri-users (n = 42). All participants completed a structural MRI scan. Voxel-based morphometry was conducted to evaluate the effect of co-use on gray matter volume, with alcohol only users as the reference group. Age, sex, and scanner were included as covariates. Results: Alcohol and tobacco co-users had significantly decreased left orbitofrontal gray matter volume relative to alcohol only users (Cohen’s d = .79). There were no differences in gray matter volume between the alcohol only and alcohol and cannabis co-users, or between the alcohol only and tri-user groups. Conclusion: The additive effect of tobacco co-use on gray matter volumes in heavy drinkers was limited and localized. The effect of tri-use of alcohol, tobacco, and cannabis may have interacted, such that overlapping cannabis and tobacco use masked volume differences present in separate co-using groups.

Combined use of alcohol and cannabis: Introduction to the special issue.

“…However, there have been relatively few investigations of the neurobiological correlates unique to combined use of cannabis and alcohol (for review, see Karoly et al, 2020). The Grodin et al (2021) article contributes to this emerging literature by examining differences in gray matter volume between individuals who use alcohol only versus those who co-use alcohol and cannabis in a relatively large sample of adults ( n = 237). The study also helps to tease apart differences in gray matter volume that are specific to alcohol and cannabis co-use versus triuse of alcohol, cannabis, and tobacco.…”

“…Relatedly, it is also imperative that future work more comprehensively considers co-use of alcohol and cannabis within the context of the use of tobacco and other substances. For example, emerging work has highlighted the importance of assessing for the triuse of alcohol, cannabis, and tobacco (Grodin et al, 2021; Roche et al, 2019). In one diary study, 40% of SAM days involved the use of another substance, primarily tobacco use and stimulant (e.g., Adderall) use (Linden-Carmichael, Van Doren, et al, 2020).…”

“…Although young adults are an important group to study, further research is needed in order to generalize findings on cannabis and alcohol co-use to additional populations. Importantly, a few studies in this special issue address questions related to the role of sex (Grodin et al, 2021; Wright et al, 2021) and race (Banks et al, 2021) in cannabis and alcohol co-use. Future work should also attempt to examine co-use behavior among older adults, additional racial/ethnic groups, samples with greater diversity with respect to sexual orientation and gender identity persons, individuals who use cannabis medicinally, and individuals in treatment for substance use, to name a few.…”

Prevalence and factors associated with substance use among HIV positive youth attending HIV care and treatment centers in Dodoma, Tanzania

“…Substance use typically begins during adolescence, and patterns of behavior related to substance use are likely to be established during this time; those patterns can lead to numerous problem behaviors and health risks affecting the life course of these individuals [8,9]. Structural neuroimaging studies suggest neural consequences may be associated with substance use [10,11]. For example, smokers and cocaine users have exhibited lower gray matter volume than non-smokers and people who do not use cocaine [11][12][13].…”

“…Structural neuroimaging studies suggest neural consequences may be associated with substance use [10,11]. For example, smokers and cocaine users have exhibited lower gray matter volume than non-smokers and people who do not use cocaine [11][12][13]. Studies have also shown that heavy alcohol use reduces gray matter loss in different brain areas, including the frontal cortex and striatum [11,14,15].…”