Post-traumatic stress disorder (PTSD) is a mental disorder that involves the development of long-lasting symptoms following exposure to life-threatening or severe traumatic event. Social phenomenon is considered as one of the most important psychosocial factors that determine whether an individual will have mental health problems and how it develops following stressor exposure, yet the specific mechanism of social interaction and social network effect on PTSD is not clear. Evidences indicated that on hand the buffering effect of social support is protective to the recovery of PTSD via positive social interactions, on the other hand post-trauma negative emotion may reverse social support thereby increasing the vulnerability of the development of PTSD. Studies have focused on the effective role of social support soothe trauma-driven disorders, yet little is known about the influence of social network in risk for PTSD. Due to the delay一onset of PTSD, the incubation period is prone to investigate the underlying mechanism PTSD and the social network during this time-window may play an important role. Researchers suggested that environment experiences include social connections, social interaction and social support during incubation period, is prone to the development of PTSD. To verify the regulating way of dyadic social interactions to PTSD, we focused on the relationship between post social network during incubation period after stress and stress induced emotional disorders, leading to a better understanding of the development and treatment of PTSD symptoms.
The current study evaluated the development of emotional sensitivity, anhedonia, anxiety一like, depression-like and sensitized fear induced by novel environment after Single prolonged stress (SPS) within a large crowd of total 60 rats reared in enriched environment. The social dynamics was observed and analyzed throughout the experimental procedure. Based on the relationship among the abnormal behaviors induced by stress and social network generated during each period, we sought to determine the regulating role of incubation-period social network to PTSD with experimental treatments of social isolation and Mutualism cooperation. Further, we aimed to reveal the underlying mechanism of social network during incubation based on the investigation of cooperation intervention on the recovery of PTSD.
In study 1，multivariate variance analysis was used to compare the PTSD-like behavioral symptoms and social network analysis was used to calculate the network indexes. Results showed that acute stress treatment as SPS induced significant PTSD-like emotional disorders as emotional sensitivity and sensitized fear and anxiety symptoms. SPS significantly altered the structure of social network as increased huddling and disturbed structure of affiliative and network stress day and post-trauma period.
In study 2, the social isolation and cooperation training were induced as two bidirectional treatments to verify the regulating effect of social interaction and network on PTSD during incubation period. We found that both isolation and cooperation interventions significantly changed post-trauma social network. At the same time, social network during incubation did not influence emotional sensitivity symptom, while social isolation specifically decreased sensitized fear response and cooperation based on social network specifically decreased anxiety responses. Counterintuitive to the known buffering effect, a strong social network connection under trauma context may worsen PTSD-like symptoms.
In study 3, cooperation versus FR1 training and incubation social network between control and SPS rats were compared. First, we found that the network-based cooperation task alleviated anxiety-like behaviors and FR1 reduced fear-like behaviors in fear response test. Further, when comparing to the differences between control and SPS groups, we also found that cooperation specifically altered in-closeness in affiliative network compared to FR1.
The present study concluded that the post-trauma incubation played a key role in the development of PTSD where the buffering effect of social factor is conditional. This referred that the risk of PTSD is highly dependent on social interaction and social network under traumatic context. These conclusions enriched theoretical studies on the delay一onset of PTSD and effect of social interaction, and provided a new prospective of post-disaster psychological assistance and further psychological intervention.