SUBSTANCE USE INITIATION AND BRAIN ACTIVATION IN EARLY ADOLESCENCE: AN INVESTIGATION OF AFFECTIVE PROCESSING AND WORKING MEMORY DEVELOPMENT

Abstract

Early adolescence represents a unique neurodevelopmental period characterized by increased risk-taking behaviors, including substance use initiation. Affective and cognitive neurodevelopment is additionally ongoing at this time, characterized by refinement of top-down executive control processes. Aberrant emotional and cognitive processes, namely affective processing and working memory, are evident in later adolescence and adulthood substance use; however, little is known about how these processes are affected by early substance use initiation. Here, this dissertation aimed to examine developmental trajectories of affective processing and working memory development in ages 9-13 and whether aberrant patterns of functional activation are observed within substance use initiators. This was completed on a nationally diverse sample of close to 12,000 youth recruited for the longitudinal Adolescent Brain Cognitive Development (ABCD) Study. Linear mixed effect models were conducted at the whole-brain level of fMRI activity elicited by an Emotional N-back task while controlling for sociodemographic, pubertal, and environmental substance use factors. Results showed no statistically significant differences between substance use initiators and non-initiators across all task contrasts. Expected functional patterns of development were observed specifically for working memory contrasts. Based on these results, preadolescent initiation may not be a robust predictor of affective processing and working memory functional processes and, instead, environmental predictors might be more closely associated with early experimentation and substance use. However, future analyses can investigate these relationships prospectively across adolescence to determine causality and elucidate subtleties, as these processes could be more impacted by repeated and regular substance use.