Memory Change and Cognitive Function among the Elderly

Abstract

The Problem: The deleterious effects of aging on various cognitive abilities are widely recognized, yet little is known regarding what constitutes normal memory test performance in individuals over the age of 74. In this study, forgetting rates for verbal and nonverbal material from the Wechsler Memory Scale-Revised (WMS-R) were examined in groups of older healthy individuals aged 50-74 and 75-95. Despite equivalent scores on measures of global cognitive status and attention/concentration, the older group demonstrated significantly poorer performance on the Delayed Memory Index. Preliminary normative data for normal elderly subjects on the WMS-R are presented, and the need for appropriate norms for elderly individuals is discussed. The Research: As part of an ongoing neuropsychological investigation of normal and abnormal aging, subjects over the age of 49 were recruited via local flyers and newspaper advertisements. For this study, subjects between the ages of 75 and 95 were included, along with a younger comparison group of individuals aged 50-74. All subjects were carefully screened via telephone interviews for neuropsychological risk factors, and those with a history of neurological disorder (e.g. stroke, head injury), learning disability, major psychiatric disorder, major medical illness or substance abuse, were excluded. The resultant sample was comprised of 30 subjects between the ages of 75 and 95, and 35 between the ages of 50 and 74. All subjects were administered the WMS-R according to standard procedure (Wechlser, 1987). For the purpose of this study, the general composite Index scores of the WMS-R were calculated for comparison of the two age groups. These general Index scores include five parameters of memory: Attention/Concentration, Verbal Memory, Visual Memory, Delayed Memory and General Memory. The Results: The older and younger groups were significantly different in terms of age, but not in educational level or the raw Attention/Concentration score. In terms of test scores, both groups obtained highly similar scores on General Memory, Visual Memory and Verbal Memory. The older group achieved a significantly lower score on Delayed Memory. These results represent some of the earliest data regarding WMS-R performance in healthy older individuals. Because of the above average level of education and excellent health status of these samples, however, the generalizability to other elderly groups (i.e. those with less education and various health risk factors) may be limited. Nevertheless, until more large scale age and education-adjusted norms are available, data such as these may serve as general preliminary guidelines for the interpretation of older subjects\u27 performance on the WMS-R

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