Traumatic brain injury, Apolipoprotein E-epsilon4, and cognition in older adults: a two-year longitudinal study.

Patients with mild-to-moderate traumatic brain injury (TBI) (N=69) were compared with age-, gender-, and education-matched healthy control group subjects (N=79) on performance of neuropsychological tests at one and 2 years following injury, and informant-rated functional abilities. All subjects were assessed for the presence of the Apolipoprotein E-epsilon4 (APOE-epsilon4) allele and rated for "mild cognitive impairment" (MCI) or dementia. Traumatic brain injury patients were no different from the comparison group on measures of cognition or functional impairment. Traumatic brain injury was not associated with higher rates of amnestic mild cognitive impairment or dementia, and APOE-epsilon4 was not associated with cognition.