Does Mild Functional Impairment Predict Dementia in Older Adults With Normal Cognition?

Objectives: Functional impairment can be an early indicator of cognitive decline. However, its predictive utility in cognitively normal (CN) older adults remains unclear. This study aimed to determine whether mild functional impairment (MFI) in CN older adults could predict incident dementia over 6 years, in addition to assessing its association with cognitive performance.

Design: A longitudinal study with a 6-year follow-up.

Participants: A cohort of 296 community-dwelling CN older adults.

Measurements: MFI was defined by cutoffs for impairment on an objective performance-based and/or subjective questionnaire-based functional assessment. Cox regression analysis was conducted to assess the relationship between MFI and risk of incident dementia and cognitive performances over 6 years. Linear regression analysis examined the association between MFI and baseline cognitive performance.

Results: There were no significant longitudinal associations between MFI and incident dementia or changes in cognitive performance over 6 years. Defining MFI using both performance-based and informant-reported assessments was predictive of dementia. Cross-sectional analyses demonstrated significant associations between MFI and poorer baseline global cognition and performance in attention, visuospatial ability, and executive functioning.

Conclusions: CN older adults with MFI were not at an increased risk of developing dementia over 6 years. A definition of functional impairment requiring both performance-based and informant-based assessments may be useful in predicting dementia.