The Influence of Spousal Genotype on Alcohol Problems in Marriage.

BACKGROUND: The field's conventional understanding of how genetic factors impact risk for alcohol use disorder (AUD) typically focuses on direct genetic effects, or how an individual's own genetic predispositions are associated with the likelihood of experiencing clinically significant alcohol problems. More recently, studies of behavioral health outcomes in preclinical and human studies have demonstrated the potential importance of social genetic effects or the influence of a social partner's genotype on substance use and related outcomes. In this study, we sought to characterize social genetic effects for AUD, specifically in the context of marriage. METHODS: The sample included 660 opposite-sex spousal dyads from the Collaborative Study on the Genetics of Alcoholism, restricted to individuals who were genetically similar to European reference panels. Measured and latent indicators of genetic risk included polygenic scores of problematic alcohol use (PGSPAU) and parental history of AUD (PHAUD), respectively. The outcome was Diaganostic and Statistical Manual (DSM)-5 alcohol use disorder criterion count (AUDcrit) during marriage. Multilevel models accounted for the non-independence of partners' data, including correlations between partners' genetic risk and residual covariance in AUDcrit. RESULTS: After accounting for direct genetic effects (i.e., the influence of one's own genetic predispositions) and the correlations between partners' genetic predispositions, we found that having a spouse with higher PGSPAU was associated with higher AUDcrit (B = 0.084, 95% CI [0.035, 0.132]). This social genetic effect was robust after adjusting for both partners' educational attainment. Spousal PHAUD was not associated with AUDcrit. Exploratory analyses indicated that the social genetic effect of spousal PGSPAU was stronger among male target individuals. CONCLUSIONS: Findings highlight the potential importance of social genetic effects for understanding the pathways from genotype to alcohol use disorder and the need for further investigation of latent measures of genetic predispositions in studies of social genetic effects.