Posttraumatic Stress Disorder and Cognitive Function

Abstract

Prior studies have found that the patients with posttraumatic stress disorder (PTSD) have poorer performance on cognitive tests than patients without PTSD, but the underlying mechanisms remain unknown. We examined the association between PTSD and cognitive function in a large cohort and evaluated the role of potential biological and behavioral mediators. A cohort of 535 adult outpatients (≤ 65 years) without dementia, stroke, or other neurologic disorders was recruited from 2 Veterans Affairs medical centers between February 2008 and June 2010. PTSD was assessed with the Clinician Administered PTSD Scale (CAPS) using DSM-IV-TR criteria. Cognitive function tests included processing speed, Trails A and B, letter fluency, category fluency, and verbal learning and recognition. Linear regression was used to evaluate the association between PTSD and cognitive function test scores and to assess potential mediators of the association. For our analyses of PTSD and cognitive function, we combined 178 participants who met criteria for full PTSD and 18 who met criteria for partial PTSD and had a CAPS score > 40. After adjusting for demographics, these participants with PTSD scored significantly worse on processing speed (0.30 standard deviations [SDs], P ≤ .001), category fluency (0.23 SDs, P = .01), verbal learning (0.30 SDs, P = .001), and verbal recognition (0.18 SDs, P = .048) than those without PTSD. These associations were largely accounted for by health behaviors, vascular risk factors, and depression. In this cohort of veterans under age 65 years without known neurologic disease, patients with versus without PTSD had significantly poorer performance in several domains of cognitive function, particularly in tests involving processing speed, executive function, and learning. These cognitive deficits were largely explained by modifiable risk factors. Interventions targeted at these risk factors might minimize the impact of PTSD on cognitive decline and dementia risk as patients age.