Objective: Although research has implicated the apolipoprotein E (APOE) epsilon-4 genotype as having a negative effect on neuropsychological outcomes following traumatic brain injury (TBI), the potentially negative role of the e4 allele on TBI outcomes has recently been challenged. In light of this debate, the present study served to examine the role of APOE genotype on neuropsychological outcomes approximately 1 month following mild to moderate TBI in a military population. Because of the well documented role of the APOE-e4 allele in increasing the risk of Alzheimer's disease, we predicted that persons with the APOE-e4 genotype would display relatively greater deficits in cognition than their non-e4 counterparts. Methods: 78 participants were consecutively recruited following a mild to moderate TBI and were divided into two groups based on the presence or absence of an APOE e4 allele. Groups were comparable on demographic characteristics and psychosocial outcomes. Participants were administered a comprehensive neuropsychological battery. Results: Analyses revealed comparable performances on most neuropsychological measures and better performances by e4 carriers on select measures of attention, executive functioning and episodic memory encoding. Furthermore, differences remained after accounting for the effects of TBI severity. Conclusions: Evidence from these analyses supports current literature refuting the notion of relatively poorer neuropsychological functioning associated with the APOE-e4 genotype among young adult participants shortly following mild or moderate brain injury. Neuropsychological performance differences by APOE genotype following TBI are discussed in terms of the importance of considering severity of injury, timing of postinjury assessment and possible neurocognitive compensatory mechanisms.

A precise estimate of the rates of traumatic brain injury (TBI) in returning combat troops is difficult to establish given the challenges of screening large numbers of military personnel returning from combat deployments. The Brief Traumatic Brain Injury Screen (BTBIS) was implemented in the First Marine Expeditionary Force between 2004 and 2006. Nine percent of the 7909 marines who completed the BTBIS were considered having a positive screen; that is, they endorsed at least one injury mechanism and indicated a change in mental status at the time of injury. The majority of combat-related TBI's were due to multiple injury agents with the next largest group related to blast exposure only. Most importantly, of those who screened positive for TBI 70.5% (n = 500) were first identified by the screen. Service members who endorsed items on the BTBIS were contacted for follow-up assessment of persistent symptoms related to TBI and clinical referrals were made as needed. Given the rate of positive TBI screens in this non-referred sample of military personnel returning from a combat deployment, routine TBI screening appears valuable in screening individuals who might not be identified otherwise. Furthermore, this study appears to refute the contention that routine TBI screening will result in an over-identification of TBI in this population. Abbreviations: OIF = Operation Iraqi Freedom; OEF = Operation Enduring Freedom; TBI = traumatic brain injury; IED = improvised explosive device; DVBIC = Defense and Veterans Brain Injury Center; WRAMC = Walter Reed Army Medical Center; PDHA = Post Deployment Health Assessment; I MEF = First Marine Expeditionary Force; BTBIS = Brief Traumatic Brain Injury Screen; NMCSD = Naval Medical Center San Diego.