Stress-Induced Inflammation and Reward Processing

Overview

Anhedonia, or loss of interest or pleasure, is a key feature of depression and transdiagnostic construct in psychopathology. Both theory and compelling evidence from preclinical models implicates stress-induced inflammation as a key psychobiological pathway to anhedonic behavior; however, this pathway has not been demonstrated in human models. Further, although anhedonia may reflect dysregulation in multiple dimensions of reward, the extent to which stress-induced inflammation alters these dimensions is unclear. The current placebo controlled study used a standardized laboratory stressor task to elicit an inflammatory response in a sample of a healthy young women and evaluate effects of stress-induced inflammation on multiple behavioral indices of reward processing.

In this study we propose to examine the association between psychosocial stress, the stress-induced inflammatory response, and reward processing in a female undergraduate sample. Specifically, we will 1) examine effects of an acute psychosocial stressor on reward processing; 2) evaluate the association between stress-related changes in inflammation and reward processing; and 3) test key vulnerability factors that may moderate the association between stress and reward. To achieve these goals, this study will recruit 60 female undergraduate students to test effects of stress on reward processing in a 3.5 hour laboratory session. Participants will be randomly assigned to either experience a laboratory stressor or a placebo control, and will complete reward tasks 90 minutes post stress/placebo onset, at which point the peripheral inflammatory response to stress reaches its peak. The reward tasks are computerized behavioral tasks that assess three domains of reward processing: reward-learning, reward motivation, and reward sensitivity. Throughout the session, all participants will complete self-report measures of affect and provide blood and saliva samples for evaluation of the psychological and physiological stress response. Within one week prior to the session, participants will attend a 1 hour visit in which they complete baseline reward tasks and self-report questionnaires assessing mood, personality, early life stress, and health behaviors. In total, participants will complete two visits, with a duration of 4.5 hours. This study builds upon prior studies demonstrating immediate effects of acute stress on reward processing, and further tests for delayed effects of acute stress on reward processing. Furthermore, this will be the first study to examine inflammation as a mechanism linking stress to deficits in reward processing. Findings may inform theory of depression etiology and contribute to more specialized treatment that is targeted at specific symptoms of depression.