Evaluating the Severity of an Unconditioned Stimulus in PTSD

Abstract

The current study investigated relationships between the severity of Posttraumatic Stress Disorder (PTSD) symptoms and the magnitude of the unconditioned response (UR) to an unconditioned aversive stimulus (US) as well responses to omission of an expected shock (CS+) and expected safety (CS-) among people who had experienced a traumatic event within the prior 2 years. Data were gathered using skin conductance response (SCR) and clinical assessments. The aims of this study were, first, to compare participants meeting DSM-5 criteria for PTSD using the Clinician-Administered PTSD Scale CAPS to those with sub-threshold CAPS scores, trauma-exposed controls (TEC) with regard to three SCR outcome variables: (1) their unconditioned response SCR to an expected US (Expect/Received) signaled by a previously reinforced (CS+) danger signal, (2) their SCR to the omission of an expected shock (Prediction Error) following a CS+, and (3) their SCR following a preceding CS- (Safety Learning). The second aim was to examine the relationships of the severity of PTSD symptoms, as assessed by the PTSD Checklist PCL-5 and CAPS, with the same 3 SCR outcome variables listed above. Participants meeting criteria for PTSD did not differ from TEC, with regard to any of the 3 SCR outcome variables. Similarly, severity of PSD symptoms did predict the values of any of the 3 above SCR outcome variables. These results suggest that other variables, such as individual disparities in resilience and coping strategies, may have had an effect on determining participants' physiological response to aversive stimuli. In the broader context, this study underscores the importance of taking into account multiple factors when attempting to apprehend the intricate relationship between PTSD symptoms and physiological responses to aversive stimuli.