Reduced awareness of surroundings is the most central domain in the network structure of posttraumatic stress disorder symptoms.

Network models suggest that co-occurring symptoms are conceptualized as a syndrome due to interactions, rather than a categorical entity with an underlying common cause. Our study aimed to examine the network structure and centrality of Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV posttraumatic stress disorder (PTSD) symptoms, including essential and associated features. We constructed a network structure of 21 intertwined symptoms, evaluated with the Clinician-Administered PTSD Scale (CAPS), in 249 PTSD patients who have been exposed to various types of traumatic events (73% being traffic or other accidents) and were beginning psychiatric treatment. In addition, we estimated the centrality of the 21 symptoms through network analysis. Each of the symptoms was defined as ordered-categorical variables. The network, with 21 symptoms, demonstrated a strong correlation among difficulty concentrating, reduced awareness of surroundings, and derealization. In addition, reduced awareness of surroundings was estimated as the most central symptom, whereas inability to recall important aspects of trauma was estimated as the least central symptom in the subjects. A community-detection analysis estimated that the 21 PTSD symptoms were organized into three clinically meaning clusters. Although dissociative features have been defined as associative symptoms rather than essential symptoms for the DSM diagnostic criteria, reduced awareness of surroundings may be regarded as the most central symptom in patients in the early phase of PTSD. Thus, evaluation and intervention for dissociative features may be needed in clinical practice and studies on PTSD.