Increased Risk of Dementia Correlates With Decreased Kidney Function 

In a registry-based study published in Neurology, individuals with reduced kidney function had increased risk of dementia development. In the study, there were cases of dementia per 1,000 person-years in individuals with a normal kidney filtration rate of 90 to 104 mL per minute and with severe kidney disease, or a filtration rate of less than 30 mL.

For the study, a database was used to identify nearly 330,000 participants age 65 years and more who had follow-up care for an average of 5 years. At the start of the study, no participants had dementia or had undergone kidney transplants or dialysis. Over the course of the study 18,983 participants (6%) were diagnosed with dementia.

Based on the study, 10% of the dementia cases could be attributed to individuals with a filtration rate of 60 mL per minute or less, which is a higher proportion of dementia cases than those attributed to other dementia risk. Estimates of the speed of kidney function decline were developed from 205,622 participants who had multiple blood tests over 1 year. Tests were used to estimate the. A steeper decline in a participant’s filtration rates during this time was also associated with a higher risk of a dementia diagnosis later on. 

After adjusting for other factors that could affect dementia risk like smoking, alcohol use, hypertension and diabetes, participants with filtration rates of 30 to 59 mL per minute had a 71% higher risk of developing dementia compared to those with normal kidney function, and participants with filtration rates of less than 30 mL per minute had a 162% higher risk.

“Our study identifies chronic kidney disease as a possible risk factor for dementia, however while it shows an association, it does not prove that it is a cause,” said study author Hong Xu, MD, PhD, of Karolinska Institute in Stockholm, Sweden. “More research is needed to determine the exact reasons for the association. Still, our findings raise awareness of the link between these 2 conditions and may help health professionals develop and implement strategies to screen for kidney disease and monitor kidney function in people at risk of dementia. Identifying and treating cases sooner may reduce the risk of dementia.”