White matter integrity, substance use, and risk taking in adolescence

Abstract

Adolescents have a higher propensity for engaging in risky behaviors, and white matter is developing prominently during the adolescent and young adult years. This study examined the influence of white matter integrity during mid adolescence (age 16-18) on subsequent (age 17 to 20) change in risk taking behaviors, including substance use. Diffusion tensor imaging and risk taking measures (including substance and other delinquent behaviors) were collected on substance users (n = 47) and controls (n = 49) at age 16 to 18. Risk taking measures were repeated 18-months later (i.e., at age 17 to 20). Tracts of interest were fronto-fronto, fronto-parietal, fronto-occipital, and fronto-limbic fiber bundles. In adolescents with heavy substance use by mid-adolescence (n = 47), lower baseline integrity of the fornix (β = -0.42, p < 0.01) and superior corona radiata (β = -0.40, p < 0.01) predicted more follow-up substance use above and beyond baseline substance use, age, and other covariates. Similarly, lower baseline fornix integrity predicted more follow-up delinquent behaviors (β = -0.26, p = 0.01). Overall, among youth who were substance users by mid-adolescence, poorer integrity in white matter pathways that typically continue development at this stage was linked to a greater propensity for risk taking behaviors into late adolescence. Most notable were relationships between projection and limbic system fibers and future substance use frequency. It is possible that an imbalance between the maturation levels in cognitive control and reward systems may disadvantage the resistance to engage in risk taking behaviors during adolescence.