Kidney Function, Kidney Function Decline, and the Risk of Dementia in Older Adults: A Registry-Based Study.

OBJECTIVE Community-based reports regarding the association between the estimated glomerular filtration rate (eGFR) and dementia risk show conflicting results. This study aims is to investigate the links between kidney function, kidney function decline and dementia incidence. METHODS We analyzed the association of eGFR with the risk of dementia (defined as a new dementia diagnosis or initiation of dementia treatments) among 329,822 residents of Stockholm who accessed healthcare during 2006-2011, were ≥65 years, had no history of dementia or underwent kidney replacement therapy. We also estimated the rate of eGFR decline among 205,622 residents with repeated eGFR measurements during the first-year of observation and investigated its association with subsequent dementia risk. RESULTS 18,983 cases of dementia (5.8% of participants) were detected over a median follow-up of 5 years. Dementia incidence rates (IR) were progressively higher with lower eGFR: from 6.56/1000 person-years in persons with eGFR 90-104ml/min to 30.28/1000 person-years in those with eGFR 2ml/min/1.73m2/year) within one year was associated with higher dementia risk. Risk magnitudes were stronger for vascular dementia than for Alzheimer. As many as 10% (95% CI 6-14%) of dementia cases could be attributed to eGFR<60ml/min/1.73m2, a proportion higher than that attributed to other dementia risk factors such as cardiovascular disease and diabetes. CONCLUSIONS Both lower kidney function and steeper kidney function decline are associated with the development of dementia.