The Effects of Preclinical Dementia on Estimates of Normal Cognitive Functioning in Aging

Individuals with preclinical dementia have begun to decline cognitively, but still perform within normal limits on cognitive testing. As a group, subjects with preclinical dementia have lower scores on neuropsychological tests than their dementia-free counterparts. This study examines the effects of...

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Bibliographic Details
Published in:The journals of gerontology. Series B, Psychological sciences and social sciences Psychological sciences and social sciences, 1996-07, Vol.51B (4), p.P217-P225
Main Authors: Sliwinski, Martin, Lipton, Richard B., Buschke, Herman, Stewart, Walter
Format: Article
Language:English
Subjects:
Age Factors
Aged
Aging
Aging - psychology
Cognition & reasoning
Cognition Disorders - diagnosis
Cognition Disorders - psychology
Dementia
Dementia - diagnosis
Dementia - psychology
Educational Status
Female
Gerontology
Humans
Longitudinal Studies
Male
Psychiatric Status Rating Scales
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Summary:Individuals with preclinical dementia have begun to decline cognitively, but still perform within normal limits on cognitive testing. As a group, subjects with preclinical dementia have lower scores on neuropsychological tests than their dementia-free counterparts. This study examines the effects of preclinical dementia on estimates of normal cognitive function in the aged using data from a longitudinal study. Individuals with preclinical dementia at baseline were retrospectively identified based on subsequent development of dementia. Age-adjusted norms were computed using baseline data for the Selective Reminding Test and the WAIS verbal and performance scores, both including (conventional norms) and then excluding (robust norms) preclinical cases. The results indicate that by failing to exclude preclinical dementia, conventional normative studies underestimate the mean, overestimate the variance, and overestimate the effect of age on cognitive measures. Methods are discussed for selecting robust elderly samples that are relatively free of contamination by preclinical dementia.
ISSN:1079-5014
1758-5368
DOI:10.1093/geronb/51B.4.P217