Common Liabilities in Internalizing Symptoms and Cigarette Use in Adolescence

Abstract

Substance use and mood disorders account for about 10% of the global burden of disease and, among adolescents, are a significant source of disability. The present study examined whether additive genetic or shared environmental factors influenced the covariance of internalizing symptoms and cigarette use during adolescence when both of these problems begin to increase. We used data (n = 1,230 pairs of twins) from the Virginia Twin Study of Adolescent Behavioral Development (mean age = 15.3) to decompose the variance of internalizing symptoms, cigarette initiation, and quantity of cigarettes smoked in a variance decomposition model that included a beta coefficient to allow for estimates of cigarette initiation to influence quantity of cigarettes smoked In biometric models we were able to equate all parameter estimates by sex. After identifying the best fitting model, parameter estimates were calculated and the significance of overlapping paths between internalizing symptoms and cigarette initiation were tested. After accounting for the genetic architecture of cigarette initiation and quantity smoked, the covariance between internalizing symptoms and cigarette use was accounted for by sex-specific shared and unique environmental factors. Among adolescents, the overlap in risk factors between internalizing symptoms and cigarette use is due to non-genetic, environmental factors. Further exploration of the environmental sources of variance involved in the onset of adolescents internalizing symptoms and cigarette use is warranted.