Abstract

Objective: The purpose of this study was to determine the frequency of change in neuropsychological performance across time in deployed military personnel who experienced traumatic brain injury (TBI). The hypothesis was that frequency of changes would decrease as a function of time since injury. Method: Test-retest data was used to calculate reliable change index scores from 114 individuals over 10 neuropsychological tests. This data, part of a database of over 1, 000 evaluations of soldiers, was collected by a private practice in association with Camp Lejeune. These soldiers were deployed to Iraq/Afghanistan and were referred for comprehensive outpatient evaluation. The second testing session was on average 14 months, with a range of 2 to 34 months, following initial testing and was necessary for medical board policy compliance. Results: Mean percentage of the sample with significant increases for neuropsychological measures for < 6, 6–18, 19–29, and 30+ months since injury respectfully include; 13%, 16%, 7%, and 10%; significant decreases respectfully include 15%, 16%, 8%, and 10%. These mean changes include: CVLT-II, COWAT, Grooved Pegboard, TMT, Stroop, and WAIS-IV. Four tests were excluded due to suboptimal sample size. WAIS-IV working memory and similarities subtests supported the hypothesis with frequencies of changes decreasing as a function of time. Conclusion(s): The hypothesis was confirmed in subtests of the WAIS-IV, where changes decrease as a function of time since injury. Overall patterns seen in each group indicated highly variable neuropsychological performance following TBI up to 6 years following injury.