Association between apolipoprotein-ε4 and long-term outcome after traumatic brain injury

Objectives: To investigate the effect of carrying the apolipoprotein epsilon 4 (APOE-epsilon 4) allele on global functional outcome, on activity limitations and participation restrictions, and on community integration at 3, 6, 12, 18, 24 and 36 months after traumatic brain injury. Method: The Glasgow Outcome Scale (GOS), the Sickness Impact Profile-68 (SIP-68) and the Community Integration Questionnaire (CIQ) were assessed in 79 moderate and severe traumatic brain injury patients at 3, 6, 12, 18, 24 and 36 months post injury. Repeated measures analyses of variance were performed with APOE-epsilon 4 status and time of measurement as independent variables and the GOS, SIP-68 and CIQ as dependent variables. Analyses were adjusted for baseline age, gender and Glasgow Coma Scale. Results: Patients with the APOE-epsilon 4 allele had a significantly better global functional outcome on the GOS than patients without the APOE-epsilon 4 allele. No significant associations were found between APOE-epsilon 4 status and the SIP-68 and CIQ. Discussion: In contrast to other studies, we found that carrying the APOE-epsilon 4 allele had a protective influence on outcome. Multiple mechanisms, and in some cases competitive mechanisms, may explain the variable relation between the APOE-epsilon 4 allele and outcome after traumatic brain injury.