The effects of aging and mild traumatic brain injury on neuropsychological performance

by Richards, Brian

Clinically, eiderly individuals show poorer outcome cornpared to young individuals following an equivalent traumatic brain injury (TBI). This could be due to either additive (aggregate) or synergistic (interactive) effects of age and TBI. This study examined the separate and combined effects of age and mild TB1 (MTBI) on neuropsychological performance in-fourgroups of 20 participants each: healthy young (M age = 26.8). young MTBI (M age = 27.5). healthy elderly (M age = 69.1) and elderly MTBI (M age = 66.7). Standard clinical measures of attention, memory, language and executive function were examined. Age-related declines were observed on measures of focused attention, verbal learning, and executive function. Error rates were low, indicating that older individuals were iess efficient but-generally accurate. MTBl participants perforrned more poorly than healthy controls on attention, verbal learning and executive function tasks. The effects of age and MTBl had a combined impact on performance in the elderly MTBI group leading to overall poorer performance as compared to other groups. This relative perfonhance deficit was due to additive rather than interactive effects of MTBl and aging factors, indicating that age and MT61 produce independent decrernents. The findings may be best explained in terrns of bain reserve capacity theory, which posits a protective factor of reserve capacity that is vulnerable to depletion via organismic and extrinsic events, and a threshold level of functioning neurons beiow which nomal function can no longer be maintained. v