Objective: Cognitive impairments are common sequelae of traumatic brain injury (TBI) and are often associated with the natural process of aging. Few studies have examined the effect of both age and TBI on cognitive functioning. The purpose of this study was to compare cognitive functioning between older adults who sustained a TBI to an age-matched group of individuals without a brain injury and to determine whether the presence or absence of a genetic marker apolipoprotein ϵ (APOE ϵ4 allele) accounts for additional cognitive decline in both groups examined.
Methods and procedures: Cognitive performance was measured by 11 neuropsychological tests, in 54 adults with TBI aged 55 and older and 40 age-matched control participants. All participants were reexamined 2 to 5 years later.
Setting: Community volunteer-based sample examined at a large, urban medical center.
Main outcome measure(s): California Verbal Learning Test; Wechsler Memory Scale–III (Logical Memory I & II; Visual Reproduction I & II); Grooved Pegboard; Woodcock-Johnson Test of Cognitive Ability (Visual Matching and Cross-out); Wisconsin Card Sorting Test; Trail Making Test A & B; Conners' Continuous Performance Task; Wechsler Adult Intelligence Scale–III (Vocabulary); Controlled Oral Word Association Test; and Boston Naming Test.
Results: Participants with TBI had lower scores on tests of attention and verbal memory than did participants with no disability. Neither group exhibited a significant decline in cognitive function over time. The presence of the APOE ϵ4 allele did not account for additional decline in cognitive function in either group.
Conclusion(s): The findings suggest that older adults with TBI may not be at increased risk for cognitive decline over short time periods (2 to 5 years) even if they are carriers of the APOE ϵ4 allele.