Hippocampal volume, brain atrophy, and APOE genotype after traumatic brain injury

Objective: To examine the association between hippocampal volumes, general brain atrophy, and apolipoprotein E (APOE) polymorphism in patients with a remote traumatic brain injury (TBI). Methods: MRI-based volumetric analyses of the hippocampus and lateral ventricles were performed in 58 patients with TBI of varying severity on average 31.3 years after the trauma. The APOE genotype was determined using standard methods and correlated with the MRI volumetric measurements. Results: Hippocampal or lateral ventricle volumes did not differ significantly in those patients with the APOE-epsilon 4 allele (APOE4) vs those without this allele. Conclusions: The APOE-epsilon 4 allele was not associated with the development of hippocampal or ventricular atrophy after traumatic brain injury. If the APOE-epsilon 4 allele is associated with an unfavorable outcome after traumatic brain injury as proposed, this association may involve mechanisms other than those responsible for the development of brain atrophy.