Cognitive function and functional ability. A cross-sectional and longitudinal study at ages 85 and 95 in a non-demented population.

We studied the relationship between cognitive function and ability in daily life activities (ADL) at ages 85 (N=332) and 95 (N=63) cross-sectionally and longitudinally in representative populations of non-demented persons, in order to focus on manifestations related to healthy aging. Among the 85-year olds, 31% were independent, 42% were dependent on personal assistance in instrumental ADL (IADL) and 27% in personal ADL (PADL); the corresponding figures for the 95-year olds were 8, 40 and 52%, respectively. Regarding the relationship between cognitive function and ADL, the analysis could only be performed in the cross-sectional data. At age 85 a significant trend was found regarding nearly all cognitive tests for both men and women, indicating that subjects who were ADL-independent had better results than those dependent in IADL, and both IADL and PADL. At age 95, no such trend was found in males, but in females the trend was significant, and those dependent in ADL had poorer results in the separate cognitive tests. By combining the different cognitive tests into a compiled cognitive index, it was seen that the most ADL-dependent persons were more cognitively impaired both at ages 85 and 95, compared to persons who were ADL-independent. Not only cognitive functioning (OR 3.3), but also mobility (OR 4.9) and tiredness (OR 3.3) were independent predictors for ADL-dependence among the 85-year olds.