Cognitive reserve and neuropsychological performance in blast exposed Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF) veterans

The purpose of this study was to examine the influence of cognitive reserve (CR) on neuropsychological test performance in a sample of Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF) Veterans with history of blast exposure. Participants were 92 previously deployed OEF/OIF Veterans divided into high and low cognitive reserve groups using a median split and grouped according to blast exposure history. Estimated cognitive reserve level was based on education level and performance on the Reynolds Intellectual Screening Test (RIST) and Wechsler Test of Adult Reading (WTAR). We compared mean standardized scores on a comprehensive neuropsychological test battery for each group. We conducted a MANOVA comparing mean scores on cognitive tests for Veterans based on blast exposure and cognitive reserve. No significant results were found for learning, memory, attention, and spatial tests. An interaction effect was found for group membership and cognitive reserve on tests of executive functioning: Veterans with high cognitive reserve who had been exposed to blast performed better on the Mazes and Categories subtests than those with low cognitive reserve; however, when there was no history of blast exposure, those with high cognitive reserve did not perform better than those with low cognitive reserve. We ran the same tests using a MANCOVA and adjusting for posttraumatic stress disorder (PTSD) scores, and found that there were no longer statistically significant differences between groups once PTSD was included as a covariate. In conclusion, higher levels of cognitive reserve may serve as a protective factor for executive functioning in Veterans with history of blast exposure, although PTSD symptoms appears to mediate this effect, consistent with existing research about the impact of psychological factors on test performance