Apolipoprotein E ε4 and short-term recovery from predominantly mild brain injury

Objective: To determine whether APOE genotype explained variability in short-term recovery from predominantly mild traumatic brain injury (TBI). Methods: A total of 87 adult patients presenting with mild or moderate TBI to a shock trauma center were enrolled prospectively. A battery of 13 neuropsychological tests was administered twice, at approximately 3 and 6 weeks after injury. Eighty of 87 patients were successfully genotyped for APOE using a buccal swab technique. Results: Ninety percent of study patients had mild TBI (Glasgow Coma Scale score of 13 to 15); 18 (22.5%) had one APOE epsilon4 and none had two epsilon4 alleles. After adjusting for potential confounders, patients positive for the APOE epsilon4 allele had lower mean scores on 12 of 13 neuropsychological outcomes at visit I compared with APOE epsilon4-negative patients. Two of the differences were significant (grooved pegboard test, p = 0.005; paced auditory serial addition task 2.8-second trial, p = 0.004). At visit 2, APOE epsilon4-positive patients had lower adjusted mean scores on 11 of the 13 neuropsychological outcomes. None of the differences was significant. Conclusions: APOE genotype may influence the severity of the acute injury. However, with no consistent pattern to the recovery curves, it is not clear if APOE genotype influences the rate of recovery.