Anhedonia in Trauma-Exposed Individuals: Functional Connectivity and Decision-Making Correlates

Abstract

Background: Reward processing deficits have been increasingly associated with trauma exposure and are a core feature of posttraumatic stress disorder (PTSD). While altered resting-state functional connectivity (rsFC) of ventral striatal regions, including the nucleus accumbens (NAcc), has been associated with anhedonia in some stress-related disorders, relationships between NAcc rsFC and anhedonia have not previously been investigated in trauma-exposed individuals. Additionally, relationships between anhedonia and reward-related decision making remain unexplored in relation to trauma exposure. We hypothesized that elevated anhedonia would be associated with altered rsFC between NAcc and default mode network regions and with increased delay discounting.

Methods: The sample included 51 participants exposed to a DSM-IV PTSD Criterion A event related to community trauma. Participants completed the Clinician Administered PTSD Scale, the Snaith-Hamilton Pleasure Scale, the Beck Depression Inventory, a computerized delay discounting paradigm, and resting-state functional magnetic resonance imaging. rsFC data were analyzed in SPM12 and CONN.

Results: Higher levels of anhedonia were associated with increased rsFC between seed regions of bilateral NAcc and areas of right dorsomedial prefrontal cortex. This relationship remained significant after accounting for Clinician Administered PTSD Scale total scores, Beck Depression Inventory total scores, or diagnostic group in the regression. Additionally, anhedonia was associated with elevated (increased) delay discounting.

Conclusions: Greater anhedonia was related to higher positive connectivity between NAcc and right dorsomedial prefrontal cortex and to increased delay discounting, i.e., greater preference for smaller immediate versus larger delayed rewards. These findings contribute to a growing body of literature emphasizing the importance of anhedonia in trauma-exposed individuals.

Keywords: Anhedonia; Delay discounting; Functional connectivity; Posttraumatic stress disorder; Resting state; Reward.