Reward functioning in PTSD: a systematic review exploring the mechanisms underlying anhedonia.

Post-traumatic stress disorder (PTSD) is a debilitating psychiatric disorder. An important diagnostic feature of PTSD is anhedonia, which may result from deficits in reward functioning. This has however never been studied systematically in PTSD. To determine if PTSD is associated with reward impairments, we conducted a systematic review of studies in which reward functioning was compared between PTSD patients and healthy control participants, or investigated in relation to PTSD symptom severity. A total of 29 studies were included, covering reward anticipation and approach ('wanting'), and hedonic responses to reward ('liking'). Overall, results were mixed, although decreased reward anticipation and approach and reduced hedonic responses were repeatedly observed in PTSD patients compared to healthy controls. Decreased reward functioning was seen more often in female than in male PTSD samples and most often in response to social positive stimuli. Though more research is needed, these findings are a first step in understanding the possible mechanisms underlying anhedonia in PTSD.