Genetic and Environmental Influences on Substance Initiation, Use, and Problem Use in Adolescents

Abstract

EPIDEMIOLOGICAL studies¹ suggest that substance use disorders are common in adults, with lifetime prevalences of 35% in men and 18% in women. The prevalence of substance use disorders is lower in adolescents (ie, 12% in males and 10% in females²), but substance use during adolescence is common. According to a recent Monitoring the Future study report,³ 80% of adolescents had used alcohol and 54% of adolescents had used an illicit drug by the end of the 12th grade. Also, early-onset substance use is a significant risk factor for the development of substance use disorders.^4,5 Although many published twin studies suggest the importance of genetic influences on substance use and substance use disorders in adults, little information regarding the cause of substance use and substance use disorders in adolescence is available. Therefore, the goal of the present study was to estimate the relative contribution of genetic and environmental influences on the risk for substance use disorders in adolescents in a combined sibling/twin/adoption study. We also examined whether the magnitude of genetic and environmental influences on the risk for substance use disorders is different for male and female adolescents. Specifically, we examined the initiation, use, and problem use for tobacco, alcohol, marijuana, and a composite variable, any drug (ie, tobacco, alcohol, marijuana, or other illicit drugs). Any drug was examined given previous evidence^6,7 of significant common genetic influences on the abuse of and dependence on different drugs.