Little is known about the role of adolescent neurodevelopment in adolescent substance abuse treatment outcomes. The development and evaluation of adolescent substance abuse treatments rarely includes consideration of varying cognitive capacities and their neural representations as determinants of individual variation in treatment response. This proposed R21 project would address this gap by identifying associations among decision making, task-related neural processing, and treatment outcome among adolescents participating in two ongoing randomized clinical trials for adolescent substance abuse. Increasing our understanding of neural processes that underlie decision making in adolescent marijuana and alcohol users would inform the development of future intervention and prevention efforts. This complementary project would draw subjects from two ongoing studies investigating contingency- management (CM) based treatments "Behavioral Treatment of Adolescent Marijuana Abuse" (DA015186), and "Family Based Contingency Management for Adolescent Alcohol Abuse" (AA016917). Both trials compare a unique CM intervention that involves an abstinence-based reinforcement program to a standard, state of the art cognitive behavioral intervention. Analyses would be performed separately for the two samples, with hypotheses tested first using the Marijuana sample, and assessed for replication/specificity using the Alcohol sample. The proposed project would explore novel neurobiological predictors of response to CM interventions. Adolescents recruited into the Marijuana Trial (n=69;23 per treatment arm) and the Alcohol Trial (n=54;27 per treatment arm) during the period of this R21 project would participate in a neuroimaging session. During the neuroimaging session, adolescents would make intertemporal choice decisions in a Delay Discounting task. Preliminary data from the Marijuana trial demonstrates significant association between performance on this behavioral delay discounting task and abstinence achieved during treatment over and above the significant effect of treatment condition. We seek to understand the neural processes that underlie performance on this laboratory task, and the degree to which variation in these neural processes relate to and predict adolescent substance abuse treatment outcomes. The conceptual framework for the proposed project is a competing neural systems model which hypothesizes a biased competition between an "impulsive" (or ''reflexive") neural system and the "executive" (or "reflective") neural system in understanding patterns of suboptimal decision making among substance-dependent individuals. An overarching hypothesis is that differing responses to distinct treatment approaches (CM vs. CBT) depend on the pattern of activation or functional connectivity within and across these competing neural systems. Specifically, we will determine the degree to which performance on a laboratory delay discounting task correlates with activity in impulsive and/or executive neural systems. We will also determine the degree to which performance on a laboratory delay discounting task and neural processing predict adolescent substance abuse treatment outcome over and above the effects of treatment condition. Finally, we will explore interactions between response to CM and delay discounting-related neural processing. This neuroimaging project will provide a springboard for the development of future projects with this newly formed interdisciplinary team. Conducting the proposed imaging study in the context of a controlled clinical trial has potential to guide the development/refinement of more efficacious treatments tailored to the individual, and may have strong implications for prevention research and intervention as well. The significance of this specific proposal is enhanced by our proposed investigation of neural predictors of response to one of the most common outpatient interventions (i.e., MET/CBT) and one of the most promising interventions for improving outcomes of MET/CBT (i.e., CM). Last, the focus on temporal discounting of rewards represents a significant test of a major theoretical construct thought to drive the addiction process. Decision making and incentive valuation represent novel targets of future treatment interventions.
This study will measure the brain activity of adolescent substance abusers while they make decisions about their preferences to receive smaller, immediate rewards vs. larger delayed rewards. We expect that patterns of brain activity while engaged in this decision making task will predict response to treatment among adolescent substance users. We expect to use the results of this study to develop more effective treatments for adolescent substance abuse.
|Stanger, Catherine; Elton, Amanda; Ryan, Stacy R et al. (2013) Neuroeconomics and adolescent substance abuse: individual differences in neural networks and delay discounting. J Am Acad Child Adolesc Psychiatry 52:747-755.e6|