The association between change in cognitive function and longevity in Dutch elderly.

The association between rate of change in cognitive function and longevity was investigated with data from the Dutch Longitudinal Study Among the Elderly. A group of 211 Dutch persons aged 65-84 years at baseline (1955-1957) was reexamined twice during an 8-year follow-up period, after which mortality was ascertained through 1983. Cognitive function was assessed based on an adaptation of the Wechsler Memory Scale. Rate of change in cognitive function during the 8 years of follow-up was determined by regression on time for each individual. Cognitive function declined significantly over the 8-year period (mean yearly change, -0.28 units; 95% confidence interval -0.34 to -0.22). The rate of decline in cognitive function was strongly associated with subsequent survival time in the ages 70 years and over, with those with a large decline having a short survival time. No association could be demonstrated in the age group 65-69 years. Adjustment for potential confounders did not affect the magnitude of the association. These findings suggest that the rate of decline of cognitive function is an independent predictor of longevity in older persons.