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.