Kidney Function and Cognitive Health in Older Adults: The Cardiovascular Health Study

This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by the Author(s) and published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. It can be found at: http://aje.oxfordjournals.org/Recent evidence has demonstrated the importance of kidney function in healthy aging. We examined the association between kidney function and change in cognitive function in 3,907 participants in the Cardiovascular Health Study, recruited from 4 U.S. communities, and studied from 1992 - 1999. Kidney function was measured by cystatin C-based estimated glomerular filtration rate (eGFR[subscript cys]). Cognitive function was assessed using the Modified Mini-Mental State Exam and the Digit Symbol Substitution Test administered up to 7 times during annual visits. There was an association between eGFR[subscript cys] and change in cognitive function after adjustment for confounders; persons with eGFR[subscript cys] < 60 ml/min/1.73m² had a 0.64 (95% confidence interval: 0.51, 0.77) point/year faster decline in Modified Mini-Mental State Exam score and a 0.42 (95% confidence interval: 0.28, 0.56) point/year faster decline in Digit Symbol Substitution Test score compared with persons with eGFR[subscript cys] ≥ 90 ml/min/1.73m². Additional adjustment for intermediate cardiovascular events modestly impacted these associations. Participants with eGFR[subscript cys] < 60 ml/min/1.73m² had fewer cognitive impairment-free life-years on average compared with those with eGFR[subscript cys] ≥ 90 ml/min/1.73m², independent of confounders and mediating cardiovascular events (-0.44, 95% confidence interval: -0.62, -0.26). Older adults with reduced kidney function are at increased risk of worsening cognitive function