Cognitive functioning and the incidence of limitations in activities of daily living in an elderly community sample.

Although it is well-known that cognitive impairment in the elderly is usually accompanied by limitations in activities of daily living (ADL), it is not known whether cognitive impairment predicts the onset of new ADL limitations. The purpose of this analysis was to determine whether poor scores on a brief measure of cognitive functioning at baseline (1982) would predict the onset of persistent limitations in ADL during the subsequent 3 years, in a probability sample of community-dwelling elderly persons living in New Haven, Connecticut, who were initially free of ADL limitations (n = 1,856). Cognitive functioning was assessed with Pfeiffer's Short Portable Mental Status Questionnaire. Persistent incident ADL limitations were defined as the onset of one or more ADL limitations after 1982, with no subsequent reports of zero ADL limitations. Compared with persons who scored zero to one errors on the Short Portable Mental Status Questionnaire at baseline, persistent, incident ADL limitations occurred more frequently in persons who scored four or more errors (odds ratio for males = 2.72, 95% confidence interval 1.36-5.43; odds ratio for females = 2.60, 95% confidence interval 1.52-4.44) after adjustment for the confounding effects of housing type, age, race, history of chronic health conditions, and incident health conditions. These results suggest that knowledge of scores on brief cognitive function tests can be used to forecast service needs and to develop intervention programs to prepare for the possible onset of ADL limitations.