Posttraumatic Stress Symptoms are Associated with Diminished Learning from Reward

Abstract

Posttraumatic stress disorder (PTSD) and subthreshold posttraumatic stress symptoms (PTSS) are associated with differences related to learning, particularly impaired fear extinction. The extinction of learned fear responses relies on neural mechanisms of reward learning, in that the absence of the expected aversive event triggers unexpected relief, which is a form of reward. Impaired learning from reward may therefore be important in the aetiology and maintenance of PTSS. PTSS have been linked to reduced reward responsiveness, but evidence regarding learning from reward is limited. This study examined whether reward learning is associated with PTSS. Participants (N = 150, 110 female) completed the Life Events Checklist and the PTSD Checklist for DSM-5 to indicate their trauma history and current PTSS. The mean PCL-5 score was 14.82, and 14 participants also reported having PTSD. Participants’ learning from reward and from punishment were derived from their performance on a probabilistic reinforcement learning task. In a linear regression model, lower reward learning, more directly experienced traumatic events, and lower age were all associated with more severe PCL-5 scores. The relationship between PTSS and reward learning appeared to be driven by the DSM-5 symptom cluster of intrusive re-experiencing, for which reward learning predicted 4.2% of the variance. Participants who reported having PTSD had poorer reward learning than those who did not. These results provide evidence for ties between poor reward learning and PTSS. This contributes to potential therapeutic approaches to the disorder, as reward learning deficits may contribute to the severity and longevity of PTSS.