Attention and the frontal lobes: A comparison between normal aging and lesion effects

Frontal lobe dysfunction has been proposed to account for age-related cognitive decline, especially with regard to memory functions. As a further test of this hypothesis, we compared the performance of aged subjects to that of patients with a unilateral frontal lesion and younger control subjects on four attentional tasks, with each task taxing different processes (Target search, Stroop interference, Digit-Symbol substitution, and Brown-Peterson short-term memory task under interference). Both the aged group and the frontal group showed attentional deficits relative to the group of younger controls on all four attentional tasks. There were differences in performance between the aged group and the frontal group that were task specific. Aged subjects showed performance comparable to that of the frontal group on the Target search and Stroop interference tasks but showed superior performance on word-reading and color naming conditions of the Stroop test, on the Brown-Peterson test, and on the Digit-Symbol substitution task. These preliminary findings could suggest that some attentional processes are more sensitive to the effect of aging than others. The differences between the aged group and the frontal group suggest specificity in deterioration in the elderly, which may reflect the functional heterogeneity of frontal lobe executive functioning, (C) 1999 Academic Press.