Reward-Related Processes and Brain Function

Impaired motivated behaviors, including aspects of decision-making and reward-related processes, lie at the root of maladaptive behavior in many psychiatric disorders, including major depression (MD). Little is known of the cognitive and neural mechanisms that underlie MD in adolescents. Adolescence is a key period during which many psychiatric disorders first emerge, and studies during this developmental stage may provide a unique window to address primary deficits associated with the disorders. In particular, major depression shows a marked increase in prevalence at adolescence. Data from family-based and longitudinal studies suggest that anxiety disorders (AD), often preceding MD, may index childhood vulnerabilities for the development of MD. The concomitant examination of MD and AD can help interpret these findings. We propose to examine, in adolescents, the manner in which the various elemental emotional-cognitive processes are differentially affected in MD and AD compared to healthy controls. This investigation will be done in two phases. In Phase I, using fMRI, we will test two tasks in the decision-making model of gambling that have similarly been tested in adults in a group of healthy adolescents and healthy adults. This phase will serve as a test of the feasibility and validity of using these tasks in adolescents, and will provide normative developmental data by comparing healthy adults with healthy adolescents. In addition to showing the feasibility of using these tasks in normal adolescents, we will also test task performance behaviorally in healthy, anxious and depressed adolescents. Measures will include psychophysiological and eye tracking measures, and behavioral variables. Once task performance is well characterized behaviorally, we will conduct in Phase II an fMRI study in independent groups of depressed and anxious adolescents and compare the findings with those obtained in healthy adolescents.