Kidney function and cognitive and functional decline in elderly adults: findings from the Singapore longitudinal aging study

Objectives: To investigate whether lower estimated glomerular filtration rate (eGFR) or chronic kidney disease (CKD) was associated with subsequent cognitive and instrumental activity of daily living (IADL) decline in a prospective cohort study.

Design: Prospective cohort study, followed for up to 4 years.

Setting: General community.

Participants: One thousand three hundred fifteen adults aged 55 and older from the Singapore Longitudinal Aging Study.

Measurements: Baseline data included eGFR levels, presence of CKD (eGFR < 60 mL/min per 1.73 m(2) ), and known confounders. Cognitive decline was defined as a drop of 2 or more points on the Mini-Mental State Examination (MMSE) and functional decline as a drop of 2 or more points in IADL score.

Results: Decreasing levels of eGFR and the presence of CKD were associated with greater odds of cognitive decline at follow-up independent of confounding risk factors in multivariate analyses: estimated 14% increment in odds of cognitive decline per 10 mL/min/1.73 m(2) decrease in eGFR (odds ratio = 1.94, 95% confidence interval = 1.23-3.05; P = .004 for CKD vs non-CKD). Similar associations were found in a cognitively normal subgroup (MMSE > 23) at baseline. In the whole sample, CKD, but not eGFR, was found to be significantly associated with higher risk of IADL decline.

Conclusion: CKD in older persons was significantly associated with cognitive and functional decline. Future research should target the development and evaluation of strategies to delay or prevent cognitive decline and physical disability in elderly adults with impaired kidney function.