Acute and Chronic Posttraumatic Stress Symptoms in the Emergence of Posttraumatic Stress Disorder

Importance: Little is understood about how the symptoms of posttraumatic stress develop over time into the syndrome of posttraumatic stress disorder (PTSD). Objective: To use a network analysis approach to identify the nature of the association between PTSD symptoms in the acute phase after trauma and the chronic phase. Design, Setting, and Participants: A prospective cohort study enrolled 1138 patients recently admitted with traumatic injury to 1 of 4 major trauma hospitals across Australia from March 13, 2004, to February 26, 2006. Participants underwent assessment during hospital admission (n = 1388) and at 12 months after injury (n = 852). Networks of symptom associations were analyzed in the acute and chronic phases using partial correlations, relative importance estimates, and centrality measures of each symptom in terms of its association strengths, closeness to other symptoms, and importance in connecting other symptoms to each other. Data were analyzed from March 3 to September 5, 2016. Main Outcomes and Measures: Severity of PTSD was assessed at each assessment with the Clinician-Administered PTSD Scale. Results: Of the 1138 patients undergoing assessment at admission (837 men 73.6% and 301 women 26.4%; mean SD age, 37.90 13.62 years), strong connections were found in the acute phase. Reexperiencing symptoms were central to other symptoms in the acute phase, with intrusions and physiological reactivity among the most central symptoms in the networks in terms of the extent to which they occur between other symptoms (mean SD, 1.2 0.7 and 1.0 0.9, respectively), closeness to other symptoms (mean SD, 0.9 0.3 and 1.1 0.9, respectively), and strength of the associations (mean SD, 1.6 0.3 and 1.5 0.3 respectively) among flashbacks, intrusions, and avoidance of thoughts, with moderately strong connections between intrusions and nightmares, being upset by reminders, and physiological reactivity. Intrusions and physiological reactivity were central in the acute phase. Among the 852 patients (73.6%) who completed the 12-month assessment, overall network connectivity was significantly stronger at 12 months than in the acute phase (global strength values, 6.57 vs 7.60; paired difference, 1.03; P < .001). The network associations among the reexperiencing symptoms were strengthened at 12 months, and physiological reactivity was strongly associated with the startle response, which was also associated with hypervigilance. Strong connectivity among emotional numbing, detachment from others, and disinterest in activities as well as moderately strong links among irritability (anger), concentration deficits, and sleep disturbance were found. Conclusions and Relevance: As time elapses after trauma, fear circuitry and dysphoric PTSD symptoms appear to emerge as connected networks. Intrusive memories and reactivity are centrally associated with other symptoms in the acute phase, potentially pointing to the utility of addressing these symptoms in early intervention strategies.