Prolonged exposure (PE) therapy is a first-line treatment for posttraumatic stress disorder (PTSD) and involves repeated presentation of trauma-related cues without aversive outcomes. A primary learning mechanism of PE is fear extinction (new learning that a dangerous cue is now safe) and its retention (maintaining this new learning over time). Extant research suggests extinction is impaired in PTSD patients. In this study, we employed an established fear-potentiated startle-based paradigm to examine fear acquisition, extinction learning and retention before and after completion of intensive outpatient treatment. First, PTSD patients undergoing PE (n = 55) were compared to trauma-exposed patients without PTSD (n = 57). We identified excessive fear in PTSD patients during acquisition and extinction before treatment compared to non-PTSD patients. At post-treatment, we examined the return of fear after extinction in PTSD patients showing high or low treatment response to PE (≥50% change in PTSD symptom severity vs. < 50%). High PE responders maintained fear extinction learning whereas low PE responders showed significant return of fear at post-treatment. These results replicate and extend previous findings of impaired extinction in PTSD and provide support for the proposed theoretical link between fear extinction and PE response.

Elucidating whether PTSD symptoms predict poorer social connectedness over time (i.e. social erosion) and/or that poor social connectedness contributes to maintenance of PTSD (i.e. social causation) has implications for PTSD treatment and relapse prevention. Most extant research has been cross-sectional and examined overall PTSD symptoms. Evidence of longitudinal associations among heterogeneous PTSD symptom clusters and social connectedness could provide insight into more nuanced targets for intervention. Using data from 1,491 U.S. military veterans in residential treatment for PTSD at 35 Department of Veterans Affairs facilities, we evaluated a two-wave cross-lagged panel model including a five-factor model of PTSD and two aspects of social connectedness. PTSD, quality of connectedness (i.e. degree of distress related to interpersonal conflict), and structural social support (i.e. number of days of contact with supportive loved ones) in the past 30 days were assessed at baseline and 4 months after discharge. The largest effect was greater severity of PTSD dysphoric arousal symptoms (i.e. irritability/anger, poor concentration, and sleep problems) at baseline predicting more conflict-related distress at follow-up (β = 0.43). Post-hoc symptom-level analyses indicated that irritability/anger drove this association. In addition, conflict-related distress predicted greater PTSD symptom severity across all five clusters (β’s = 0.10 to 0.14, p’s < 0.01). More days of contact predicted lower severity of avoidance and numbing symptoms (β’s = −.05 and −.07, p’s < 0.01), along with individual symptoms within these clusters, plus flashbacks. Results support both social erosion and social causation models. Engaging loved ones in veterans’ treatment and targeting dysphoric arousal symptoms, particularly anger and irritability, may improve long-term PTSD and relationship outcomes, respectively.