Association between kidney function and incidence of dementia: 10-year follow-up of the Whitehall II cohort study

BACKGROUND: Cognitive dysfunction is common in haemodialysis patients but whether poor kidney function in the general population is also associated with higher risk of dementia remains unclear. OBJECTIVE: To examine the association of kidney function with incident dementia in community dwelling older adults. DESIGN: Whitehall II prospective study. SETTING: Population-based study on 6,050 adults, mean age 65.8 in 2007–2009. METHODS: Poor kidney function, defined as estimated Glomerular Filtration Rate (eGFR) <60 ml/min/1.73 m2 in 2007–2009, and adverse change in eGFR was defined as decrease ≥4 ml/min/1.73 m2 between 2007–2009 and 2012–2013. Incident dementia was ascertained through linkage to electronic health records, and Cox regression was used to examine associations with dementia. RESULTS: A total of 306 cases of dementia were recorded over a mean follow-up of 10 years. Baseline eGFR <60 was associated with a hazard ratio (HR) for dementia of 1.37 (95% CI 1.02, 1.85) in analysis adjusted for sociodemographic factors, hypertension, obesity, stroke, diabetes and cardiovascular disease/medication. Removing stroke cases at baseline and censoring them over the follow-up yielded an HR of 1.42 (95% CI 1.00, 2.00) for the association between CKD and dementia. Decline of eGFR ≥4 between 2007–2009 and 2012–2013 was associated with incidence of dementia over a 6.3 year mean follow-up (HR: 1.37; 95% CI 1.02, 1.85), with somewhat stronger associations when analyses were restricted to those with eGFR ≥60 in 2007–2009 (1.56; 95% CI: 1.12, 2.19). CONCLUSION: Poor and declining kidney function in older adults is associated with a higher risk of dementia that is not attributable to stroke and persists after accounting for major cardiometabolic conditions.