Assessment of functional change and cognitive correlates in the progression from healthy cognitive aging to dementia

There is currently limited understanding of the course of change in everyday functioning that occurs with normal aging and dementia. To better characterize the nature of this change, we evaluated the types of errors made by participants as they performed everyday tasks in a naturalistic environment.

Participants included cognitively healthy younger adults (YA; n = 55) and older adults (OA; n = 88), and individuals with mild cognitive impairment (MCI: n = 55) and dementia (n = 18). Participants performed 8 scripted everyday activities (e.g., filling a medication dispenser) while under direct observation in a campus apartment. Task performances were coded for the following errors: inefficient actions, omissions, substitutions, and irrelevant actions.

Performance accuracy decreased with age and level of cognitive impairment. Relative to the YAs, the OA group exhibited more inefficient actions which were linked to performance on neuropsychological measures of executive functioning. Relative to the OAs, the MCI group committed significantly more omission errors which were strongly linked to performance on memory measures. All error types were significantly more prominent in individuals with dementia. Omission errors uniquely predicted everyday functional status as measured by both informant-report and a performance-based measure.

These findings suggest that in the progression from healthy aging to MCI, everyday task difficulties may evolve from task inefficiencies to task omission errors, leading to inaccuracies in task completion that are recognized by knowledgeable informants. Continued decline in cognitive functioning then leads to more substantial everyday errors, which compromise ability to live independently.