The Impact of Polygenic Risk, Parental Separation, and Parental Relationship Discord on Heavy Episodic Drinking Across Adolescence and Young Adulthood in a High-Risk Sample

Objective: Parental separation and relationship discord are linked to alcohol use behaviors, but their influence on the longitudinal course of alcohol misuse and interactions with genetic predisposition remain unclear. This study examined how the longitudinal course of heavy episodic drinking (HED) from adolescence to young adulthood varies with polygenic risk, parental separation, and relationship discord. Method: Participants were from the Collaborative Study on the Genetics of Alcoholism (COGA) Prospective Sample, and included individuals from 2 genetically inferred continental groups: European-like (EA; n = 1761) and African-like (AA; n = 894) who were reassessed biennially (mean age = 16.39 at first assessment; mean assessments = 4.65). Alcohol misuse was indexed by past-year HED frequency. Predictors included parental separation, parental relationship discord, and problematic alcohol use polygenic scores (PGS_PAU). Data were analyzed using linear mixed-effects growth models. Results: HED increased through young adulthood before declining. In European Americans (EA), parental separation was associated with HED intercepts, but not with linear slope or quadratic curvature. Higher PGS_PAU was associated with a faster initial growth and slower decline. In African American (AA), parental relationship discord was not associated with HED intercepts but was associated with a faster initial growth and slower decline. PGS_PAU were not associated the intercept or the course of HED. No interaction was found between PGS_PAU and parental separation or discord to predict the longitudinal course of HED in either EA or AA samples. Conclusion: Genetic risk and exposure to parental separation and discord are associated with the course of HED, with some differences across continental groups. Plain language summary: This study utilized data from the Collaborative Study on the Genetics of Alcoholism (COGA) to examine how the course of heavy episodic drinking (HED) from adolescence to young adulthood varies with genetic risk, parental separation, and relationship discord. Parental separation and relationship discord were associated with initial levels of heavy episodic drinking and their course into young adulthood. In the European American sample, these family stressors were associated with higher initial levels of heavy episodic drinking, which were sustained over time with genetic factors amplifying this pattern. In the African American sample, parental relationship discord was associated with a rapid increase in heavy episodic drinking that declined slowly. These findings highlight the contributions of genetics and family adversity in shaping risk for harmful patterns of alcohol use across development.