The Relationship Between Trauma Exposure, Trauma Recency, and Anhedonia with Skin Conductance Responsivity to Reward

Most individuals will experience a traumatic event in their lifetime, and many will go on to live with negative consequences, principle among them mental health problems such as posttraumatic stress disorder (PTSD). PTSD is a debilitating psychiatric condition marked by both exaggerated threat responding and diminished positive affect. A large proportion of trauma-exposed individuals experience anhedonia, or an inability to feel pleasure, reflective of reward processing deficits. Notably, diminished positive affect has been shown to exist among individuals exposed to trauma without resulting PTSD diagnosis. Prior work also indicates that reduced reward responsivity may be a central feature in the development and chronicity of negative outcomes of trauma, such as trauma-related stress disorders. Despite this, the biological underpinnings of reward processing deficits in trauma-exposed samples remain poorly understood. We investigated group differences in physiological response to reward between participants with versus without trauma exposure. Second, we tested the contribution of specific mechanisms by which impairments in reward processing may manifest in trauma-exposed individuals by testing the relationship between trauma recency and anhedonia severity with physiological response to reward. Participants completed a validated fear, reward, and neutral conditioning task in the lab; reward outcome was manipulated such that participants were exposed to conditioned stimuli (CS) that predicted a steadily increasing reward receipt. Physiological response was quantified using skin conductance responses [SCRs] in response to reward CSs among participants with (n = 77) and without ( n= 42) trauma exposure. No group differences (trauma vs. non-trauma exposed) emerged during the task and we did not find evidence that recency of trauma exposure was related to physiological reward response. By contrast, anhedonia moderated the relationship between trauma exposure and physiological arousal to reward. In the trauma-exposed group, greater hedonic deficits and lower positive emotionality were related to lower physiological responding to baseline conditioned reward. When reward was scaled, those without trauma exposure but high in trait negative affect interference exhibited greater physiological responding. Findings highlight anhedonia as a relevant factor related to individual differences in physiological response to conditioned reward cues, and thus a meaningful marker of reward processing abnormalities in trauma survivors.