Attentional disengagement deficit in nondemented elderly over 75 years of age

Abstract

Healthy older adults in the age range of 60-75 years are moderately deficient in visuospatial attention when central location cues are used to shift attention, but not when peripheral cues are used. In contrast, older adults with dementia of the Alzheimer's type (DAT) exhibit an attention shifting (disengagement) deficit for both central and peripheral cues. If the effects of dementia and normal aging on visuospatial attention differ qualitatively, then peripherally cued shifts of attention should be unaffected even in very old nondemented persons. to examine this possibility, subjects in six age groups (17-24, 35-44, 45-54, 55-64, 65-74, and 75-85 years) were tested on a visuospatial attention task. Valid, invalid and neutral location cues preceded a letter target requiring, in separate conditions, either speeded detection or discrimination. Combined costs and benefits of cue validity on reaction time (RT) increased with age in the discrimination but not in the detection task. the oldest group (75-85) showed significantly larger RT costs and benefits than the next oldest group (65-74), for both central and peripheral cues. the 75-85 year-olds were significantly slower than the 65-75 year-olds on invalid trials (costs) but not on valid trials (benefits), pointing to a disengagement deficit, as reported previously for patients with either parietal lobe damage or DAT. the results suggest that in healthy nondemented subjects of advanced age (over 75 years), visuospatial attention is affected similarly to younger patients in the early, mild stages of Alzheimer's disease.