Neurocognitive mechanisms of poor social connection in posttraumatic stress disorder: Evidence for abnormalities in social working memory

Background Poor social connection is a central feature of posttraumatic stress disorder (PTSD), but little is known about the neurocognitive processes associated with social difficulties in this population. We examined recruitment of the default network and behavioral responses during social working memory (SWM; i.e., maintaining and manipulating social information on a moment‐to‐moment basis) in relation to PTSD and social connection. Methods Participants with PTSD (n = 31) and a trauma‐exposed control group (n = 21) underwent functional magnetic resonance imaging while completing a task in which they reasoned about two or four people's relationships in working memory (social condition) and alphabetized two or four people's names in working memory (nonsocial condition). Participants also completed measures of social connection (e.g., loneliness, social network size). Results Compared to trauma‐exposed controls, individuals with PTSD reported smaller social networks (p = .032) and greater loneliness (p = .038). Individuals with PTSD showed a selective deficit in SWM accuracy (p = .029) and hyperactivation in the default network, particularly in the dorsomedial subsystem, on trials with four relationships to consider. Moreover, default network hyperactivation in the PTSD group (vs. trauma‐exposed group) differentially related to social network size and loneliness (p's