Decreasing kidney function appears to be strongly linked to the development of dementia in patients aged 65 and over, according to a recent study.
“Some studies have looked at the relationship between kidney function and the risk of dementia. Our results agree with most and can help fill in some discrepancies in the literature to date that may be due to low sample sizes and the dichotomization of kidney function, ”said study co-author Juan-Jesus Carrero, PharmD, PhD, Professor of Epidemiology at Karolinska Institutet in Stockholm, Sweden.
If the associations identified in the study prove to be causal, neurologists may be able to lower the risk of dementia or slow cognitive function with therapies that delay the progression of kidney disease, said Dr. Carrero. Until this is proven, our study creates awareness of the relationship between these two conditions. Nephrologists who suspect signs of dementia in people with kidney disease should refer them to a neurologist. Likewise, neurologists could take the opportunity to examine and monitor kidney disease while working on patients with dementia, he said.
Dr. Carrero and colleagues analyzed the association between the estimated glomerular filtration rate (eGFR) and risk of dementia in 329,822 Stockholm residents who had access to health care between 2006 and 2011. All subjects were 65 years of age or older, had no history of dementia, and had not received renal replacement therapy. They had an average age of 74 years and 56% were women. The mean estimated glomerular filtration rate (eGFR, in ml / min / 1.73 m2) was 75. The most common comorbid conditions were high blood pressure (40%), cancer (17%), diabetes mellitus (12%), depression (12%) . Atrial fibrillation (11%), heart failure (9%), stroke (7%) and myocardial infarction (7%).
The primary outcome was the first recorded diagnosis of all-cause dementia or the initiation of anti-dementia drugs (donepezil, rivastigmine, galantamine, and / or memantine). The researchers also assessed the association between dementia and the rate of eGFR decline in 205,622 participants with repeated eGFR measurements in the first year of observation.
Dr. Carrero identified 18,983 cases of dementia (5.8%) over a mean follow-up of 5 years. The incidence rates for dementia increased as the eGFR fell. Dementia rates were 6.56 cases per 1000 person-years in patients with an eGFR of 90-104, compared to 30.28 cases per 1000 person-years in patients with an eGFR of less than 30, the researchers reported.
After adjusting for other identified factors that might influence the risk of dementia, such as smoking, alcohol use, high blood pressure, and diabetes, the researchers found that older adults with an eGFR of 30 to 59 and less than 30 had a 1.7- and 2.6 -fold higher risk of dementia compared to those with normal kidney function (eGFR 90-104).
According to the investigators, 10% of dementia cases could be traced back to an eGFR of 60 or less. This is a higher proportion of dementia cases than other dementia risk factors such as cardiovascular disease and diabetes. “A novelty in our study is the observation that people with a faster decline in kidney function over a year are linearly exposed to a higher risk of dementia. This compliments our primary analysis and increases the credibility of the association between these two diseases, ”said Dr. Carrero told Renal & Urology News.
The authors found that there are no effective treatments available to slow down or prevent dementia. Hence, it is important to identify possible modifiable risk factors. “Our findings can help healthcare decision makers develop and implement appropriate strategies for screening and monitoring for dementia in people with CKD (and vice versa),” they write.
A key strength of the study was the availability of complete medical records for an entire region with universal access to health care. In addition to the observation design, one limitation of the study was that it only included patients with a diagnosis of dementia. It is possible that many patients have undiagnosed dementia.
“It’s a good study and the largest of its kind,” said Dr. Leighton R. James, Professor in the Department of Nephrology at the Medical College of Georgia, Augusta. The study provides a better understanding of the link between kidney disease and dementia.
He noted that large prospective studies are warranted and that studies looking at genetic and blood markers in patients who have been followed for long periods of time could help answer key clinical questions. “Some studies say there is no association, but I can say that in patients with advanced kidney disease, the toxins acutely build up and cause dementia,” said Dr. James. “That happens in the short term, but in the long term we don’t know anything.”
Xu H., Garcia-Ptacek S., Trevisan M. et al. Renal function, renal impairment, and risk of dementia in older adults: a registry-based study. Neurology. Published online May 5, 2021. doi: 10.1212 / WNL.0000000000012113
This article originally appeared in the Renal and Urology News