Poor kidney function significantly linked to incidence of dementia

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Data from a 10-year follow-up study showed that declining kidney function is significantly associated with the risk of dementia in older adults.

Results from a 10-year follow-up cohort study revealed that poor and declining kidney function in older adults is associated with a higher risk of dementia. The findings, published in Age and aging, also showed that the association is not attributable to stroke and persists after controlling for major cardiometabolic conditions, the authors wrote.

Previous research has indicated that cognitive impairment is common in patients with end-stage renal disease on hemodialysis, while there is a graded association between chronic kidney disease (CKD) severity and cognitive impairment.

“The kidneys and the brain, both end organs, are thought to be susceptible to vascular injury due to similar anatomical and hemodynamic characteristics,” the researchers explained, proposing a possible common underlying mechanism.

Globally, the prevalence of CKD is increasing in part due to rising rates of hypertension, diabetes, and obesity.

To further elucidate the relationship between estimated glomerular filtration rate (eGFR) and dementia, researchers assessed data that had been compiled over more than 10 years in a large community dwelling as part of the Whitehall II Cohort Study. . This study was established in 1985 and originally included data on 10,308 people. Since the start of the study, follow-up clinical examinations have taken place every 4 to 5 years, while in the current analysis, baseline kidney function data measured between 2007 and 2009 were used.

The data was also linked to UK National Health Service electronic health records and dementia from all causes was identified based on International Classification of Diseases, 10th Revision codes. Individuals were followed up to the recorded date of dementia, death, or March 31, 2019.

Changes in eGFR were measured at follow-up appointments that took place between 2012 and 2013. A total of 6050 adults with a mean age of 65.8 (5.9) years were included in the study. current analysis.

The researchers found:

  • 306 cases of dementia were recorded over an average follow-up of 10 years
  • A baseline eGFR
  • Deleting stroke cases at baseline and censoring them during follow-up gave an RR of 1.42 (95% CI, 1.00-2.00) for the association between CKD and dementia
  • Decline in eGFR ≥ 4 between 2007 to 2009 and 2012 to 2013 was associated with the incidence of dementia over a mean follow-up of 6.3 years (RR, 1.37; 95% CI, 1.02-1, 85), with somewhat stronger associations when analyzes were restricted to those with eGFR ≥ 60 from 2007 to 2009 (RR, 1.56; 95% CI, 1.12-2.19)

The mean (SD) age at diagnosis of dementia was 78.1 (5.3) years and these individuals tended to have poorer baseline sociodemographic and health profiles.

Overall, the researchers noted 3 key findings:

  • The threshold eGFR
  • A robust association of eGFR
  • Decreased eGFR, even when restricted to analysis on people with baseline eGFR ≥ 60, was associated with higher incidence of dementia

The current findings are consistent with previously published research, but the exact underlying mechanisms linking the 2 conditions remain unclear.

In the Whitehall II analysis, the researchers could only adjust for traditional risk factors, marking a limitation to the study. Included participants were also more likely to be healthier than those with advanced kidney disease, while the follow-up period used “is not long enough to rule out converse causes where estimates may be biased due to the long preclinical phase of dementia affecting multiple processes,” the authors wrote.

The cost of care, rising CKD prevalence rates and poor outcomes warrant prioritizing CKD surveillance from a public health perspective, the researchers concluded. “Although cardiovascular disease and reduced life expectancy are recognized adverse effects of CKD, it is possible that dementia is also part of the risk associated with CKD.”

Reference

Singh-Manoux A, Oumarou-Ibrahim A, Machado-Fragua MD, et al. Association between renal function and incidence of dementia: 10-year follow-up of the Whitehall II cohort study. Age Aging. Published online January 17, 2022. doi:10.1093/ageing/afab259

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