Association of Changes in Intrinsic Capacity With Cognitive Decline and Dementia: A Prospective Cohort Study.

Abstract (English)

BACKGROUND AND OBJECTIVES: Previous studies found that intrinsic capacity (IC) was an important risk factor for dementia. However, these studies focused on baseline IC, without considering the dynamic changes in IC. The study aimed to investigate the associations of changes in IC with cognitive decline and dementia and assess whether these associations varied by race. METHODS: A cohort study was conducted using data from the Health and Retirement Study. An IC deficit score was calculated by 7 factors reflecting 4 domains. Changes in IC were assessed by comparing the baseline IC status with that observed in the second survey. Cognitive decline was evaluated by computing a standardized z-score based on memory, executive function, and orientation. Dementia was diagnosed either through self-reported physician diagnosis or an alternative approach based on cognitive score. Linear mixed effects models and Cox models were performed to analyze the association of changes in IC with cognitive decline and dementia. RESULTS: A total of 7,744 participants (male: 42.4%, mean age: 75.6 years) were included. The median follow-up period was 8.9 years. Compared with participants who maintained robust IC status, those whose IC status progressed to deficit status showed accelerated global cognitive decline (&#x3b2;, -0.025; 95% CI -0.036 to -0.015) and increased risk of dementia (hazard ratio [HR], 1.38; 95% CI 1.10-1.72). Conversely, participants who recovered from IC deficit to robust status showed decelerated global cognitive decline (&#x3b2;, 0.010; 95% CI 0.001 to 0.019) and decreased risk of dementia (HR, 0.84; 95% CI 0.72-0.98) relative to those with stable IC deficit. In addition, the associations of baseline IC with cognitive decline and dementia appeared to be somewhat stronger among Black participants, relative to White participants (<i>p</i> for interaction = 0.011). Significantly decelerated global cognitive decline in IC deficit participants who recovered to robust status was observed exclusively among Black participants. DISCUSSION: The findings indicated that the progression of IC deficit status was associated with accelerated cognitive decline and increased risk of dementia. Conversely, recovery of IC deficit status was associated with a decelerated cognitive decline and decreased risk of dementia. Future studies with more measurement waves are warranted to validate these findings.