Predicting Alcohol Dependence Symptoms by Young Adulthood: A Co-Twin Comparisons Study

Area of Science:

• Psychiatry
• Behavioral Genetics
• Developmental Psychology

Background:

• Familial confounding, including shared genetics and environment, complicates understanding of alcohol dependence (AD) etiology.
• Co-twin comparison designs offer a powerful method to disentangle these familial influences.

Purpose of the Study:

• To investigate associations between adolescent factors and young adult alcohol dependence (AD) symptoms using a co-twin comparison design.
• To identify specific adolescent risk and protective factors for AD that persist after controlling for familial confounding.

Main Methods:

• Utilized data from 1286 individuals (581 complete twin pairs) from the FinnTwin12 study.
• Examined associations between adolescent predictors (academic achievement, substance use, behavioral problems, peer environment, parent-child relationship, etc.) and lifetime AD clinical criterion count in young adulthood.
• Employed both individual-level and co-twin comparison analyses to assess the robustness of findings.

Main Results:

• Adolescent substance use, externalizing problems, internalizing problems, peer deviance, and perceived life event difficulty were associated with higher AD symptoms.
• Higher academic achievement, social adjustment, self-rated health, and parent-child relationship quality were linked to fewer AD symptoms.
• Associations for substance use, externalizing problems, internalizing problems, peer deviance, and self-rated health remained significant in co-twin comparisons, indicating resilience to familial confounding.

Conclusions:

• Replicated known adolescent correlates of later alcohol problems, including academic, behavioral, and social factors.
• Demonstrated the utility of co-twin comparisons in identifying robust predictors of alcohol dependence.
• Adolescent substance use, externalizing problems, internalizing problems, peer deviance, and self-rated health are key targets for intervention to prevent alcohol dependence.