February 20, 2017 – Neural activity in childhood predicts adolescent substance use initiation
Substance use at an early age conveys substantial risk for later substance-related problems. One study found that those who began using drugs before age 14 had a lifetime dependence rate that was twice as high as those who started after 21. A better understanding of the early risk factors could result in more timely and effective intervention. The aim of this study was to investigate the predictive utility of neural functioning as a risk factor for early substance use initiation.
Subjects were 53 children (16 F) from an ongoing longitudinal functional magnetic resonance imaging study, scanned at a mean age of 10.5 yrs (SD 1.1). Twenty subjects later initiated substance use (mean age 13.6, SD 1.2; users); 33 subjects did not (controls). We used monetary incentive delay and go/no-go tasks to examine the hemodynamic response to reward anticipation and failed inhibitory control, respectively. Independent components analysis and logistic regression were used to test the hypothesis that brain response patterns would have predictive utility over and above two known risk factors for substance use problems—externalizing behavior and family history (FH) of substance use disorder (SUD)—in the differentiation of users and controls.
Nucleus accumbens activation during reward anticipation significantly predicted group membership (p = .046), whereas failed inhibitory control components did not. Using the likelihood ratio test, the model that also included neural data was significantly better than the model that had only externalizing and FH variables (p = .004).
Heightened reward responsivity in the nucleus accumbens may predispose individuals to early substance use, beyond the risk conveyed by other known factors. In contrast, failed inhibitory control appears to be less influential at this age. Future studies should investigate the possibility that, later in development, both reward responsivity and inhibitory control components are predictive of SUD in young adults.