Social integration and inflammation in individuals with and without posttraumatic stress disorder

Abstract

Background: Posttraumatic stress disorder (PTSD) is associated with increased risk for morbidity and mortality, which may be mediated through elevated inflammation. In contrast, social support appears to protect against morbidity and mortality, reduce levels of inflammation, and improve PTSD outcomes.

Methods: We examined relationships among social isolation, perceived social support, and inflammation in Veterans Affairs (VA) patients with and without PTSD. Our sample included 735 (35% PTSD+) participants from the Mind Your Heart Study (mean age = 58 ± 11; 94% male). Social isolation was assessed with the Berkman Syme Social Network Index; perceived social support with the Multidimensional Scale of Perceived Social Support; and PTSD with the Clinician Administered PTSD Scale. Inflammation was indexed by high sensitivity C-reactive protein, white blood cell count, and fibrinogen. Hierarchical linear regression was used to examine associations between social measures and inflammation. PROCESS was used to examine the interactive effects of social relationships and PTSD on inflammation.

Results: Social isolation, but not low perceived social support, trended towards an association with elevated inflammation in the full sample. However, considering groups with and without PTSD separately, social isolation was significantly associated with all inflammatory markers among individuals without PTSD, but not among those with PTSD.

Conclusions: Social integration is associated with reduced inflammation in individuals without, but not with, PTSD. Socially integrated individuals with PTSD did not have lower levels of inflammatory markers than socially isolated individuals with PTSD.

Keywords: Immune System; Inflammation; PTSD; Perceived Social Support; Posttraumatic Stress Disorder; Social Isolation; Social Network; Social Support.

Figure 1A-C.

Relationship between Social Network Index (SNI) Category and Inflammation by Posttraumatic Stress Disorder (PTSD) Status. Figure shows mean levels with standard errors of log-transformed inflammatory markers, including high sensitivity C-reactive protein (hsCRP), white blood cell (WBC) count, and fibrinogen. SNI of 1 is most socially isolated, while SNI of 4 is most socially integrated.