Background: Few studies have examined the relationship between non-cognitive factors and activities of daily living (ADL) according to Alzheimer's disease (AD) stage.
Objective: We aimed to identify the differences in non-cognitive factors according to AD stages and their involvement in basic and instrumental ADL performance by using intrinsic capacity (IC) in groups with cognition ranging from normal to moderate or severe AD.
Methods: We enrolled 6397 patients aged≥65 years who visited our memory clinic. Non-cognitive IC was assessed using the locomotion, sensory, vitality, and psychological domains. Multiple logistic regression was performed to identify how non-cognitive IC declines over the AD course and examine the correlation between non-cognitive IC and basic and instrumental ADL performance.
Results: Non-cognitive IC declined from the initial AD stage and was significantly correlated with both basic and instrumental ADL performance from the aMCI stage through all AD stages. In particular, the relationship between IC and basic ADL was stronger in mild and moderate to severe AD than in the aMCI stage. On the other hand, the relationship between IC and instrumental ADL was stronger in aMCI than in later AD stages.
Conclusions: The results show non-cognitive factors, which decline from the aMCI stage, are correlated with ADL performance from the aMCI stage to almost all AD stages. Considering that the relationship strength varied by ADL type and AD stage, an approach tailored to ADL type and AD stage targeting multiple risk factors is likely needed for effectively preventing ADL performance declines.
Keywords: Alzheimer’s disease; basic activities of daily living; instrumental activities of daily living; intrinsic capacity.