A Co-Twin Control Study of the Relationship Between Adolescent Drinking and Adult Outcomes

Genetic and shared environmental factors explain the association between adolescent polysubstance use and high school noncompletion

OBJECTIVE

Examine the nature of the relationship between adolescent polysubstance use and high school noncompletion.

METHOD

Among a sample of 9,579 adult Australian twins (58.63% female, Mage = 30.59), we examined the association between the number of substances used in adolescence and high school noncompletion within a discordant twin design and bivariate twin analysis.

RESULTS

In individual-level models controlling for parental education, conduct disorder symptoms, childhood major depression, sex, zygosity, and cohort, each additional substance used in adolescence was associated with a 30% increase in the odds of high school noncompletion (OR = 1.30 [1.18, 1.42]). Discordant twin models found that the potentially causal effect of adolescent use on high school noncompletion was nonsignificant (OR = 1.19 [0.96, 1.47]). Follow-up bivariate twin models suggested genetic (35.4%, 95% CI [24.5%, 48.7%]) and shared environmental influences (27.8%, 95% CI [12.7%, 35.1%]) each contributed to the covariation in adolescent polysubstance use and early school dropout.

CONCLUSIONS

The association between polysubstance use and early school dropout was largely accounted for by genetic and shared environmental factors, with nonsignificant evidence for a potentially causal association. Future research should examine whether underlying shared risk factors reflect a general propensity for addiction, a broader externalizing liability, or a combination of the two. More evidence using finer measurement of substance use is needed to rule out a causal association between adolescent polysubstance use and high school noncompletion. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Prospective associations between adolescent risky substance use and school dropout and the role of externalising and internalising problems

Background: The aim of the present study was to assess to what extent risky substance use (RSU) acts as an important risk factor for school dropout from upper secondary school in a prospective study of Norwegian adolescents, and how externalising and internalising mental health problems influenced this association. Methods: We used data from a large population-based survey (the youth@hordaland-survey), which included adolescents aged 16-19 years. The predictor variables were self-reported RSU. The survey was linked with prospective data from the Norwegian Education Database, following the adolescents to 21-23 years of age. The outcome variable was registry-based school dropout within five years after starting upper secondary school. The analyses were adjusted for sex, age, socioeconomic status, and externalising and internalising problems. Results: After adjustment for sociodemographic variables, all indicators of RSU were prospectively associated with school dropout (adjusted odds ratios 1.26-2.25; all p values <.01). While internalising problems only slightly changed these estimates, the associations were substantially attenuated by externalising problems. Still, all measures of RSU, except frequent alcohol intoxication, remained positively associated with school dropout in the fully adjusted models. For the youngest students, all associations between RSU and school dropout were significant. Conclusions: Adolescent RSU is a strong predictor for school dropout, and externalising problems explained a considerable proportion of this effect. Prevention efforts to reduce student substance could improve academic outcomes among upper secondary school students, and such efforts may benefit from also targeting co-occurring externalising problems.

Polygenic risk score for problematic alcohol use predicts heavy drinking and alcohol use disorder symptoms in young adulthood after accounting for adolescent alcohol use and parental alcohol use disorder

BACKGROUND

Genome-wide association studies (GWAS) have identified hundreds of loci associated with alcohol-related traits. GWAS permit the calculation of polygenic risk scores (PRS), which aggregate genetic risk for a trait across the genome. To evaluate the usefulness of a PRS for problematic alcohol use (PAU)-which subsumes alcohol use disorder (AUD) and alcohol-related problems-we tested whether this PRS predicted heavy drinking and alcohol problems after accounting for family history of AUD and prior drinking history, robust and established predictors of PAU.

METHODS

Participants (N=665) were European-ancestry members of the Michigan Longitudinal Study, a prospective family study with high rates (65%) of parental AUD. Participants reported their frequency of alcohol use, maximum drinks consumed in a 24-hour period, and alcohol use problems at four assessments in adolescence and young adulthood (11-29 years old). We used polygenic prediction via Bayesian regression and continuous shrinkage priors to create a PAU PRS using summary statistics from a meta-GWAS of PAU.

RESULTS

After adjusting for demographic covariates, parental AUD, and drinking and alcohol use problems in early and mid/late adolescence, the PAU PRS was significantly associated with alcohol-related problems in young adulthood (β=.08, p=.047; R2=0.6%). The PAU PRS also had a significant indirect effect on alcohol use problems in young adulthood through earlier drinking and alcohol use problems (β=.02, p=.03).

CONCLUSIONS

The PAU PRS predicted alcohol problems in young adulthood after accounting for parental history of AUD and alcohol use in adolescence, providing evidence that genetic data uniquely inform the etiology of alcohol problems.

Do Australian adolescents with permission to drink at home engage in different alcohol use behaviours and experience more harms than those without such permission?

INTRODUCTION

Around half of Australian students aged 16-17 are estimated to have drunk alcohol in the past month, with 11% drinking at 'risky' levels. This study investigated: (i) how many Australian adolescents aged 16-17 had parental permission to drink at home in 2016/17 and whether prevalence differed by adolescent sex; (ii) whether adolescents allowed to drink at home had drunk more recently and were drinking greater quantities; (iii) if adolescents allowed to drink at home experienced more alcohol-related harms; and (iv) if parental drinking patterns were associated with permitting adolescents to drink at home.

METHODS

Data from Wave 7 of the Longitudinal Study of Australian Children were used. Descriptive and bivariate analyses addressed Aims i-iii. Nested multivariable logistic regression models addressed aim iv.

RESULTS

In 2016/17, 28% of Australian adolescents aged 16-17 were allowed to drink alcohol at home. More adolescents with permission had drunk alcohol in the past month (77% vs. 63% of those without permission). There was no difference in quantity of alcohol consumed in the past week between groups. More adolescents allowed to drink at home had experienced alcohol-related harm compared to those without permission (23% vs. 17%). In multivariable analyses, alcohol consumption by primary parents was associated with an increased likelihood of allowing adolescents to drink at home.

DISCUSSIONS AND CONCLUSIONS

In order to reduce adolescent alcohol use and associated harms, parents should avoid permitting alcohol use among adolescents at home. Frequent (twice or more/week) primary parental alcohol consumption was especially associated with greater odds of allowing adolescents to drink at home.

Adolescent substance use and high school noncompletion: exploring the nature of the relationship using a discordant twin design

BACKGROUND AND AIMS

Previous studies have demonstrated associations between substance use and reduced educational attainment; however, many were unable to account for potential confounding factors like genetics and the rearing environment. In the few studies that controlled for these factors, the substances assessed were limited to alcohol, cannabis, and tobacco. To address these limitations, we examined the relationship between adolescent use of seven kinds of substances, the number of additional substances used, and high school noncompletion within a large sample of Australian twins.

DESIGN

A series of two-level generalized mixed effects logistic regressions were conducted to examine associations between adolescent substance use and high school noncompletion.

SETTING

Australia.

PARTICIPANTS

A total of 9579 adult Australian twins from two cohorts of the Australian Twin Registry.

MEASUREMENTS

Assessments of high school completion, childhood major depression, conduct disorder symptoms, substance use initiation, demographics, and parental educational attainment using the Australian version of the Semi-Structured Assessment for the Genetics of Alcoholism.

FINDINGS

There were unique within-twin-pair effects of use of sedatives (odds ratio [OR] = 22.39 [95% confidence interval (CI) = 1.18-423.48]) and inhalants/solvents (OR = 10.46 [95% CI = 1.30-84.16]) on high school noncompletion. The number of substances used in adolescence was strongly associated with high school noncompletion across all discordant twin models (ORs from 1.50-2.32, Ps < 0.03).

CONCLUSIONS

In Australia, adolescent substance use appears to be associated with early school dropout, with the effects of any given substance largely because of the confounding factors of parental education, childhood conduct disorder symptoms, and use of other substances. Sedatives and inhalants/solvents have effects on high school noncompletion that cannot be explained by polysubstance use or familial factors.

Educational Attainment Polygenic Scores: Examining Evidence for Gene-Environment Interplay with Adolescent Alcohol, Tobacco and Cannabis Use

Genes associated with educational attainment may be related to or interact with adolescent alcohol, tobacco and cannabis use. Potential gene-environment interplay between educational attainment polygenic scores (EA-PGS) and adolescent alcohol, tobacco, and cannabis use was evaluated with a series of regression models fitted to data from a sample of 1871 adult Australian twins. All models controlled for age, age², cohort, sex and genetic ancestry as fixed effects, and a genetic relatedness matrix was included as a random effect. Although there was no evidence that adolescent alcohol, tobacco or cannabis use interacted with EA-PGS to influence educational attainment, there was a significant, positive gene-environment correlation with adolescent alcohol use at all PGS thresholds (ps <.02). Higher EA-PGS were associated with an increased likelihood of using alcohol as an adolescent (ΔR² ranged from 0.5% to 1.1%). The positive gene-environment correlation suggests a complex relationship between educational attainment and alcohol use that is due to common genetic factors.

Exploring the relationships between adolescent alcohol misuse and later life health outcomes

BACKGROUND

We sought to clarify the impact of adolescent alcohol misuse on adult physical health and subjective well-being. To do so, we investigated both the direct associations between adolescent alcohol misuse and early midlife physical health and life satisfaction and the indirect effects on these outcomes attributable to subsequent alcohol problems.

METHOD

The sample included 2733 twin pairs (32% monozygotic; 52% female) from the FinnTwin16 study. Adolescent alcohol misuse was a composite of frequency of drunkenness, frequency of alcohol use, and alcohol problems at ages 16, 17, and 18.5. The early midlife outcomes included somatic symptoms, self-rated health, and life satisfaction at age 34. The mediators examined as part of the indirect effect analyses included alcohol problems from the Rutgers Alcohol Problem Index at ages 24 and 34. Serial mediation and co-twin comparison models were applied and included covariates from adolescence and early midlife.

RESULTS

There were weak direct associations between adolescent alcohol misuse and early midlife physical health and life satisfaction. However, there was stronger evidence for indirect effects, whereby young adult and early midlife alcohol problems serially mediated the relationship between adolescent alcohol misuse and early midlife somatic symptoms (β = 0.03, 95% CI [0.03, 0.04]), self-rated health (β = -0.02, 95% CI [-0.03, -0.01]), and life satisfaction (β = -0.03, CI [-0.04, -0.02]). These serial mediation effects were robust in co-twin comparison analyses.

CONCLUSIONS

These results provide evidence that alcohol problems are a primary driver linking adolescent alcohol misuse and poor health outcomes across the lifespan.

A latent class analysis of heavy substance use in Young adulthood and impacts on physical, cognitive, and mental health outcomes in middle age

BACKGROUND

This study examines whether longitudinal patterns of persistent or experimental heavy substance use across young adulthood were associated with physical and mental health in midlife.

METHODS

Data (N = 21,347) from Monitoring the Future from adolescence (age 18) to midlife (age 40) were used. Repeated measures latent class analysis modeled patterns of patterns of cigarettes, alcohol, marijuana, and other illicit drugs across young adulthood (ages 18-30). Latent classes were then used as predictors of physical health problems, cognitive problems, self-rated health, and psychological problems in midlife (age 40), while controlling for sociodemographic variables (i.e., gender, race/ethnicity, parental education).

RESULTS

Identified classes were "Extreme Heavy Users" (3.9%), "Early Young Adult Users" (8.9%), "Cigarette Smokers" (9.2%), "All But Cigarette Smokers" (5.0%), "Frequent Alcohol Bingers" (10.4%), and "Not-Heavy Users" (62.6%). Extreme Heavy Users, Early Young Adult Users, and Cigarette Smokers had significantly poorer overall health based on a number of physical conditions and self-rated health. Extreme Heavy Users, Early Young Adult Users, Cigarette Smokers, and All But Cigarette Smokers had more cognitive problems than other classes. Extreme Heavy Users, Early Young Adult Users, Cigarette Smokers, and All But Cigarette Smokers were more likely to see a health professional for a psychological problem.

CONCLUSIONS

Patterns of heavy substance use were associated with health across decades. Regular cigarette smokers and heavy users across substances and ages had the worst health in midlife, although even those with time-limited use during young adulthood were at risk for later physical and cognitive health problems.