Genetic risk for schizophrenia influences substance use in emerging adulthood: An event-level polygenic prediction model

Abstract

Emerging adulthood is a peak period of risk for alcohol and illicit drug use. As genetic risk for schizophrenia has been previously associated with substance use disorders, we examine how schizophrenia-associated genetic variants are related to trajectories of five substance use behaviors as they occurred in daily life across emerging adulthood. Non-Hispanic European participants provided DNA samples and completed daily reports of alcohol and drug use for one month per year across four years (N=28,372 individual observations of N=318 participants). The present study yields two major insights. First, results indicated that genetic risk for schizophrenia predicted emerging adults9 overall likelihood to engage in illicit drug use and polysubstance use (concurrent illicit drug use and alcohol use or binge drinking), but did not predict alcohol use-only phenotypes. Second, the present findings suggest that genetic variants related to schizophrenia predict the rate of age-related change in substance use.