Neurocognitive functions and everyday functions change together in old age.

OBJECTIVE: Although neurocognitive functions are known to decline normatively with adult age, there is a common belief that everyday functions (e.g., paying bills, following medication instructions, making change, looking up telephone numbers in a phone book) are unaffected by these changes.
METHOD: This hypothesis was examined by applying longitudinal growth models to data from a community-based sample of 698 adults (ages 65 to 94 years and living independently at baseline) who were repeatedly measured over five years on neurocognitive tests of executive reasoning, episodic memory, and perceptual speed, and on a number of tasks that adults should be reasonably expected to be able to perform in their day-to-day lives.
RESULTS: Individual differences in changes in neurocognitive performance were strongly correlated with individual differences in changes in performance on the everyday tasks. Alternatively, changes in self-reports of everyday functions were only weakly correlated with changes in performance on the neurocognitive tests and the everyday tasks.
CONCLUSIONS: These results together suggest that normative neurocognitive aging has substantial consequences for the daily lives of older adults and that both researchers and clinicians should be cautious when interpreting self-reports of everyday functioning.