Stage‐specific behavioral, cognitive, and in vivo changes in community residing subjects with age‐associated memory impairment and primary degenerative dementia of the Alzheimer type

Abstract

Stage-specific relationships between the seven-stage Global Deterioration Scale (GDS) for age-associated memory impairment and primary degenerative dementia of the Alzheimer's type and behavioral, cognitive, and neuroradiologic changes were examined in community residing subjects with normal aging or Alzheimer's disease (AD). The results revealed significant decrements between GDS stages 2 and 3; 3 and 4; 4 and 5; and 5 and 6 for most behavioral measures. No decrements were noted between GDS stages 1 and 2. Consequently, the subjective complaints of cognitive decrement, which characterize GDS 2 subjects and which commonly accompany aging, do not appear to be accompanied by objective behavioral or cognitive change. Floor effects for most behavioral and cognitive measures occurred by GDS 6, with nearly uniform bottom scores by GDS stage 7. Computerized tomographic (CT) assessments of brain change revealed significant relationships with global severity on the GDS, but few significant consecutive stage decrements were noted. The magnitude of the relationship between CT assessments of brain change and GDS scores was notably less than the magnitude of the relationship noted between various behavioral measures and GDS. Although behavioral and neuroradiologic measures studied did not reveal decrements in the GDS 2 subjects in comparison with age-rnatched GDS 1 subjects who do not have subjective decrements, previous studies of a neuroimmunologic measure (brain reactive antibody levels) do appear to have indicated significant differences between these groups. Consequently, there is some current preliminary evidence for the hypothesis of a physiologic substrate for the subjective deficits characteristic of the GDS 2 stage, as well as clear-cut behavioral data distinguishing each of the subsequent GDS stages of aging and AD.

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