576. Accelerated Neurodegeneration: Effects of Cumulative Trauma Exposure and Chronic Posttraumatic Stress Disorder (PTSD) in Relatively Young Combat Veterans

Abstract: Background: We previously published that combat veterans with PTSD (CV1PTSD) compared to healthy combat veterans (HCV) had significantly reduced gray matter volume (GMV) of olfactory cortex that was inversely related to burning odor sensitivity. Given that olfactory deficits (smell identification) are an early symptom of neurodegenerative disorder, and that some consider PTSD a disorder of accelerating aging, we sought to examine olfactory GMV and smell identification as a function of age in combat veterans with and without PTSD. Methods: In this preliminary, cross-sectional study, 20 CV1PTSD (Age: M530.4, SD58.4) and 25 HCV (Age: M530.8, SD57.1) underwent a full clinical/trauma evaluation, standard smell identification testing, and a structural MRI exam. Results: Of all variables including age, the only predictor of GMV in olfactory cortex of HCV was trauma load, quantified as the number and frequency of different traumatic event types (F1, 185 12.5, p,.01). As trauma load increased, GMV of piriform cortex decreased (r52.48, p5.01). Significant Diagnosis X Time (post-trauma) interactions revealed that the decreased olfactory GMV and impaired odor identification previously reported in CV1PTSD was driven primarily by the older veterans who had been ill the longest (ps,.05). Conclusions: The current results demonstrate an association between trauma load and reduced olfactory GMV, an effect that may be magnified, and accompanied by impaired function, with repeated stressor-related events. Combined with our previous findings, we hypothesize that specific odor sensitivities may predict early and accelerated neurodegeneration across a spectrum of psychiatric and neurologic disorders