Abstract
ObjectiveCommunity-based reports regarding the association between the estimated glomerular filtration rate (eGFR) and dementia risk show conflicting results. The aim of this study is to investigate the links among kidney function, kidney function decline, and dementia incidence.MethodsWe 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 health care during 2006 to 2011, were ≥65 years of age, 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.ResultsWe detected 18,983 cases of dementia (5.8% of participants) over a median follow-up of 5 years. Dementia incidence rates were progressively higher with lower eGFR: from 6.56/1,000 person-years in those with eGFR of 90 to 104 mL/min to 30.28/1,000 person-years in those with eGFR <30 mL/min. After multivariable adjustment, lower eGFR was associated with a higher dementia risk (hazard ratio [HR] 1.71, 95% confidence interval [CI] 1.54–1.91 in eGFR 30–59 mL/min; HR 2.62, 95% CI 1.91–3.58 in eGFR <30 mL/min) compared with eGFR of 90 to 104 mL/min. A steeper decline in eGFR (decline >2 mL/min/1.73 m2/y) within 1 year was associated with higher dementia risk. Risk magnitudes were stronger for vascular dementia than for Alzheimer dementia. As many as 10% (95% CI 6%–14%) of dementia cases could be attributed to eGFR <60 mL/min/1.73 m2, a proportion higher than that attributed to other dementia risk factors such as cardiovascular disease and diabetes.ConclusionsBoth lower kidney function and steeper kidney function decline are associated with the development of dementia.
Highlights
Dementia, the progressive decline of cognition and functioning beyond that of the normal aging process[1] occurs mostly in old age, with a prevalence estimate of 5% at 65-74 years, 20% at 75-84 years and 50% in those over 85 years[2]
After applying exclusion criteria, the study cohort consisted of 329,822 participants free from dementia history and aged ≥65 years
Higher incidence rates (IR) were noted for participants with Chronic kidney disease (CKD) stage 3 or more [6.56/1000py in estimated glomerular filtration rate (eGFR) 90-104, 15.74/1000py in eGFR 60-89, 26.8/1000py in eGFR 30-59 and 30.3/1000py in eGFR
Summary
The progressive decline of cognition and functioning beyond that of the normal aging process[1] occurs mostly in old age, with a prevalence estimate of 5% at 65-74 years, 20% at 75-84 years and 50% in those over 85 years[2]. Chronic kidney disease (CKD), the persistent reduction in kidney function, is very common among older adults, with a population prevalence of 25-40% depending on age strata[6]. Even a mild reduction in kidney function, as defined by estimated glomerular filtration rate (eGFR), is associated with a markedly increased risk of comorbidities, such as cardio and cerebrovascular disease[7, 8], infections[9], anemia[10], and possibly, dementia. Previous studies on the association between kidney function and the incidence of dementia diagnosis show conflicting results[19,20,21,22,23,24,25,26,27,28,29] that might be due to fundamental differences as regards e.g. methods to assess kidney function or dementia, study population (size and selection criteria) and inclusion of confounders[26]
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