PTSD and cognitive functioning: importance of including performance validity testing

Many studies have observed an association between post-traumatic stress disorder (PTSD) and cognitive deficits across several domains including memory, attention, and executive functioning. The inclusion of response bias measures in these studies, however, remains largely unaddressed. The purpose of this study was to identify possible cognitive impairments correlated with PTSD in returning OEF/OIF/OND veterans after excluding individuals failing a well-validated performance validity test. Participants included 126 men and 8 women with a history of mild traumatic brain injury (TBI) referred for a comprehensive neuropsychological evaluation as part of a consortium of five Veterans Affairs hospitals. The PTSD CheckList (PCL) and Word Memory Test (WMT) were used to establish symptoms of PTSD and invalid performance, respectively. Groups were categorized as follows: Control (PCL < 50, pass WMT), PTSD-pass (PCL ≥ 50, pass WMT), and PTSD-fail (PCL ≥ 50, fail WMT). As hypothesized, failure on the WMT was associated with significantly poorer performance on almost all cognitive tests administered; however, no significant differences were detected between individuals with and without PTSD symptoms after separating out veterans failing the WMT. These findings highlight the importance of assessing respondent validity in future research examining cognitive functioning in psychiatric illness and warrant further consideration of prior studies reporting PTSD-associated cognitive deficits.