Physical Inactivity During Adolescence Heightens Risk for Cannabis Use Disorder in Adulthood

The association between physical inactivity and substance use throughout adolescence was prospectively investigated in relation to developing cannabis use disorder (CUD). Physical inactivity and substance use in males (N = 462) and females (N = 178) were measured at 12-14, 16, 19, and 22 years of age in a repeated measures design. A structured diagnostic interview was administered to formulate current CUD diagnosis at 22 years of age. Mixture modeling path analysis evaluated the association between physical inactivity, substance use, and CUD. Males: Slope of physical inactivity increase spanning 12-22 years of age mediates the association between number of parents with substance use disorder (SUD) and rate of increase in substance use frequency (prodrome) which mediates the association between physical inactivity (hypothesized vulnerability) and CUD. Females: Number of SUD parents predicts slope of physical inactivity increase in daughters throughout adolescence which covaries with slope of increasing substance use frequency culminating in CUD. The association between parental SUD load (number of SUD affected parents) and CUD was found to not be mediated by physical inactivity. Rate of increase in physical inactivity during adolescence in males and females is a facet of the vulnerability for CUD. These results have ramifications for prevention considering that numerous cognitive, behavior, and emotion features of CUD vulnerability are attenuated by exercise. Public Health Significance Showing that SUD in parents predicts offspring's rate of increase in physical inactivity throughout adolescence spanning 10-22 years of age, in conjunction with the finding that slope of increase in physical inactivity covaries with substance use frequency which impacts risk for CUD, has important practical implications for enhancing prevention effectiveness. Specifically, inculcating a physically active lifestyle ameliorates the psychological characteristics of CUD vulnerability.