Alcohol-related genes show an enrichment of associations with a persistent externalizing factor

Relationships among impulsive, addictive and sexual tendencies and behaviours: a systematic review of experimental and prospective studies in humans

Impulsivity's relationships to addictive and sexual behaviours raise questions regarding the extent impulsivity may constitute a vulnerability factor for subsequent addictive and sexual behaviours and/or results from each of these. Here, we systematically reviewed empirical support for impulsivity as a precipitating factor or a consequence of addictive or sexual behaviours. We restricted ourselves to recent, human studies with assessments over time, including at least one measure of impulsivity, addictive and sexual behaviours, yielding a review including 29 published reports from 28 studies. Findings point to generalized, self-reported impulsivity as a predictor of addictive and sexual behaviours at a wide range of severity, with elements of both impulsivity and compulsivity to these acts. Alcohol consumption often increases impulsive behaviour, including inclinations towards impulsive and potentially compulsive sexual acts. Research using the Sexual Delay Discounting Task has yielded findings linking impulsivity, addictive and sexual behaviour and as such is a valuable research tool that should be used more extensively. The present review identified gaps to be addressed in further research that concurrently examines facets of impulsivity, addictive and sexual behaviours, especially because criteria for compulsive sexual behaviour disorder have been included in the eleventh edition of the International Classification of Diseases. This article is part of the theme issue 'Risk taking and impulsive behaviour: fundamental discoveries, theoretical perspectives and clinical implications'.

[Internalizing and externalizing behavior problems and substance use in adolescence]

This study investigated the relationship between externalizing behavior problems (EBP), internalizing behavior problems (IBP), and combined externalizing/internalizing behavior problems (EIBP) in early adolescence (11 years) and substance use (alcohol, tobacco, and illegal drugs) at 15 years, using data from the 1993 Pelotas (Brazil) birth cohort. Behavior problems were assessed with the Strengths and Difficulties Questionnaire (SDQ), applied to mothers when their children were 15 years old. Substance use was assessed with a self-applied confidential questionnaire for the adolescent. The association between behavior problems and substance use was analyzed with Poisson regression with robust adjustment of variance. After adjusting for confounding, adolescents with EBP showed higher risk of alcohol abuse (RR = 1.74, 95%CI: 1.21; 2.50) and experimentation (RR = 1.78, 95%CI: 1.42; 2,23) and tobacco use in the previous 30 days (RR = 2.38, 95%CI: 1.64; 3.45). Adolescents with IBP showed greater risk of having tried tobacco (RR = 1.54, 95%CI: 1.22; 1.93) and of having used tobacco products in the previous 30 days (RR = 1.92, 95%CI: 1.31; 2.83). Adolescents with EIBP showed greater risk of trying (RR = 2.24, 95%CI: 1.57; 3.21) and consuming tobacco products in the previous days (RR = 3.01, 95%CI: 1.63; 5.56), and lower risk of having tried alcohol at 15 years of age (RR = 0.72, 95%CI: 0.55; 0.94). Public health measures aimed at reducing behavior problems in early adolescence can help reduce tobacco and alcohol consumption at 15 years.

Post-GWAS in Psychiatric Genetics: A Developmental Perspective on the "Other" Next Steps

As psychiatric genetics enters an era where gene identification is finally yielding robust, replicable genetic associations and polygenic risk scores, it is important to consider next steps and delineate how that knowledge will be applied to ultimately ameliorate suffering associated with substance use and psychiatric disorders. Much of the post-genome-wide association study discussion has focused on the potential of genetic information to elucidate the underlying biology and use this information for the development of more effective pharmaceutical treatments. In this review we focus on additional areas of research that should follow gene identification. By taking genetic findings into longitudinal, developmental studies, we can map the pathways by which genetic risk manifests across development, elucidating the early behavioral manifestations of risk, and studying how various environments and interventions moderate that risk across developmental stages. The delineation of risk across development will advance our understanding of mechanism, sex differences and risk and resilience processes in different racial/ethnic groups. Here, we review how the extant twin study literature can be used to guide these efforts. Together, these new lines of research will enable us to develop more informed, tailored prevention and intervention efforts.

GABRA2, alcohol, and illicit drug use: An event-level model of genetic risk for polysubstance use

GABRA2, the gene encoding the α2 subunit of the GABAA receptor, potentially plays a role in the etiology of problematic drinking, as GABRA2 genotype has been associated with subjective response to alcohol and other alcohol-related reward processes. The GABRA2 gene has also been associated with illicit drug use, but the extent to which associations with drug use are independent of associations with alcohol use remains unclear, partly because most previous research has used a cross-sectional design that cannot discriminate comorbidity at the between-person level and co-occurrence within-persons. The present study used a daily monitoring method that assessed the effects of GABRA2 variation on substance use as it occurred in the natural environment during emerging adulthood. Non-Hispanic European participants provided DNA samples and completed daily reports of alcohol and drug use for 1 month per year across 4 years (N = 28,263 unique observations of N = 318 participants). GABRA2 variants were associated with illicit drug use in both sober and intoxicated conditions. Moreover, the effect of GABRA2 variation on drug use was moderated by an individual's degree of intoxication. These findings are consistent with recent genetic and neuroscience research, and they suggest GABRA2 variation influences drug-seeking behavior through both alcohol-related and alcohol-independent pathways. (PsycINFO Database Record

Developmentally Specific Associations Between CNR1 Genotype and Cannabis Use Across Emerging Adulthood

OBJECTIVE

Previous studies have found preliminary evidence for associations between common single-nucleotide polymorphisms (SNPs) in the cannabinoid receptor gene CNR1 and cannabis use and dependence. The present study examined a set of eight independent SNPs in or near CNR1 in relation to cannabis use measured longitudinally across emerging adulthood.

METHOD

Using latent growth curve modeling of 10 waves of longitudinal data spanning mean ages 18.4-23.8 years in a sample of non-Hispanic White individuals (n = 334), we tested if genotype at each CNR1 SNP was associated with both level and growth of cannabis use over time. Peer group drug use, a known correlate of individual use, was evaluated as a time-varying predictor of cannabis use and as a moderator of the relationship between SNPs and individual use.

RESULTS

After correction for multiple comparisons, one SNP, rs806374, was significantly associated with individual differences in level-but not growth-of cannabis use over time, such that C carriers were more likely to use cannabis more frequently at study onset (around age 18). Peer drug use was a predictor of individual cannabis use that grew in terms of effect size with time, but did not significantly moderate the effect of rs806374 genotype.

CONCLUSIONS

C carriers at rs806374 may be at specific risk for increased odds of use during the transition out of high school (around age 18). Future studies should investigate potential mechanisms at this developmental stage, including individual differences in subjective response, innate tolerance, reinforcement mechanisms, or general liability for substance misuse.

Freshman year alcohol and marijuana use prospectively predict time to college graduation and subsequent adult roles and independence

OBJECTIVE

This study examined how freshman year substance use prospectively predicted time to college graduation, and whether delayed graduation predicted postponed adoption of adult roles and future substance use.

PARTICIPANTS

Participants were part of a longitudinal study that began in 2004. The first analyses focused on freshman year (N = 2,050). The second analyses corresponded to a subset of participants at age 27 (N = 575).

METHODS

Measures included self-reported substance use, adult role adoption, and university reported graduation dates.

RESULTS

Results indicated that frequent binge drinking and marijuana use during freshman year predicted delayed college graduation. Those who took longer to graduate were more likely to have lower incomes and were less likely to obtain a graduate degree. Taking 5-6 years to graduate was associated with greater likelihood of alcohol-related problems.

CONCLUSIONS

Findings support the importance of interventions during freshman year of college to decrease substance use and promote timely graduation.