Neural reward sensitivity and longitudinal patterns of alcohol and cannabis use in college-aged youth

BACKGROUND: Alcohol and cannabis are commonly used substances among adolescents, yet the neurobiological mechanisms that confer risk for alcohol and cannabis use disorder remain poorly understood. Abnormalities in neural reward processing have been implicated in the etiology of substance use disorders, but their predictive utility is unclear. Identifying such risk factors is critical for developing prevention and intervention strategies for high-risk youth. METHOD: We examined whether deficits in neural reward processing predicted changes in problematic alcohol and cannabis use symptoms in youth (ages 16-19, n = 172) with minimal prior substance use. At baseline, the reward positivity (RewP), an event-related potential (ERP) measured via electroencephalography, was used to index deficits in neural reward processing. Every 3 months for 2 years, participants reported problematic cannabis and alcohol use symptoms. To examine changes in substance use problems, we conducted a series of linear mixed-effects models (LMMs). RewP amplitude was the key predictor and linear and quadratic terms for time were included as fixed effects. RESULTS: In our cannabis use model, we observed a significant linear time X RewP interaction. Lower RewP amplitude predicted increases in cannabis use problems over 24-months. At higher levels of RewP amplitude, there was no effect of time on cannabis use problems. We did observe a positive effect of time on alcohol use problems. We found no main/interactive effects of RewP on alcohol use problems. CONCLUSIONS: A blunted RewP is a robust predictor of risk for cannabis use problems, offering potential for early identification and targeted intervention in vulnerable youth.