Cognitive paths from trauma to posttraumatic stress disorder: a prospective study of Ehlers and Clark's model in survivors of assaults or road traffic collisions

Abstract

Background: Individual differences in cognitive responses to trauma may represent modifiable risk factors that could allow early identification, targeted early treatment and possibly prevention of chronic posttraumatic stress disorder (PTSD). Ehlers and Clark's cognitive model of PTSD suggests that negative appraisals, disjointed trauma memories, and unhelpful coping strategies maintain PTSD. These are thought to be influenced by cognitive processing during trauma. The aim of this study was to test this model prospectively with path analyses.

Methods: Participants (N = 828) were recruited from an emergency department following injury in a violent assault or road traffic collision and 700 participated in the 6-month assessments. Cognitive processing was assessed shortly after the event, negative appraisals, disjointed memories, and unhelpful coping strategies at 1 month, persistent PTSD symptom severity at 6 months, and early PTSD symptom severity at 2 weeks.

Results: Cognitive variables, with trauma type and gender, explained 52% of the variance in PTSD symptom severity at 6 months. Including early symptom severity in the model did not explain more variance (53%). Early PTSD symptom severity, with trauma type and gender, only predicted 40%. Negative appraisals and disjointed memories predicted persistent symptom severity both directly and indirectly via unhelpful strategies. Peritraumatic processing predicted persistent symptom severity mainly indirectly. The effects of trauma type and gender were fully mediated by the cognitive factors.

Conclusions: The results are consistent with theoretically derived predictions and support cognitive factors as indicators of risk for chronic PTSD and as a target for the treatment and prevention of PTSD.

Keywords: Appraisals; cognitive processing; dissociation; memory; posttraumatic stress disorder; rumination.

Fig. 1.

Conceptual figure of cognitive factors leading to chronic PTSD according to Ehlers and Clark's (2000) model.

Fig. 2.

(a) Path model for Ehlers and Clark's (2000) cognitive model of PTSD. Cognitive processing during trauma was assessed within hours up to 10 days after the traumatic event; appraisals, memory characteristics, safety behaviours, responses to intrusions and ongoing dissociation were assessed 1 month after the traumatic event, and persistent posttraumatic stress disorder symptoms were assessed 6 months after the traumatic event. Trauma type is coded as 0 (road traffic collision) and 1 (assault), gender is coded as 0 (male) and 1 (female). Continuous lines with arrows pointing in one direction show standardized path coefficients, dashed lines with double headed arrows show correlations (in italics). R² = percentage of explained variance, ***/**/* = p < 0.001/<0.01/<0.05. (b) Path diagram of the cognitive model extended by early symptoms. Thick continuous lines with arrows pointing in one direction show standardized path coefficients for the predictions of the cognitive factors and early PTSD symptom severity, thin continuous lines with arrows pointing in one direction show standardized path coefficients for effects of trauma type (coded as 0 = road traffic collision and 1 = assault) and gender (coded as 0 = male and 1 = female), and dashed lines with double headed arrows and values in italics font show correlations. R² = percentage of explained variance, ***/**/* = p < 0.001/<0.01/<0.05.