Prospective assessment of psychophysiological risk factors for PTSD

Rationale/statement of the problem : There is an urgent need to develop biological and behavioral predictors of PTSD risk/resilience in individuals with high trauma exposure, such as active military duty. First, we will briefly review psychophysiological risk factors for PTSD. Second, we will describe preliminary data from a prospective study of active duty Marines examining psychophysiological responses before and after deployment to Iraq or Afghanistan. Third, we will discuss our cross-species work in animal models of PTSD risk/resilience to inform these study findings. Methods : This study was conducted as part of a 4 h battery (clinical, psychosocial, laboratory, and psychophysiological assessments) conducted both before, and 3 and 6 months after deployment (Marine Resiliency Study) in >2,500 Marines. Here, we examined (1) effect of deployment overall on physiological reactivity measures on baseline startle, pre-pulse inhibition, and affective modulation of startle and (2) comparison of pre-deployment startle reactivity across subjects matched for combat exposure with and without PTSD symptoms, 3 months post-deployment. Results : We observed small but significant increases in baseline startle and pre-pulse inhibition after deployment. Startle potentiation to aversive images was also significantly increased after deployment. Importantly, baseline startle magnitude before deployment was significantly greater in subjects that went on to develop PTSD symptoms after deployment compared to their combat-matched controls. Conclusions : These results support previous reports suggesting that startle reactivity may probe trait biological processes that confer risk for PTSD symptoms. To complement these findings, we (1) are conducting a similar prospective study to determine if fear conditioning and extinction performance predicts deployment-related stress disorders and (2) have developed a homologous rodent model to aid identification of potential epigenetic mechanisms underlying psychophysiological and fear-processing risk factors.