People with impaired kidney function have higher levels of Alzheimer's disease biomarkers in their blood, but this does not translate into a greater risk of developing dementia, according to new research published on December 3, 2025, in Neurology, the journal of the American Academy of Neurology.
The study was led by Francesca Gasparini, MD, from Karolinska Institutet in Stockholm. Gasparini stated, "Our study found that when the kidneys are not functioning properly, there may be higher levels of Alzheimer's biomarkers in the blood. While we did not find that having reduced kidney function increased the risk of developing dementia, we did find that impaired kidney function may accelerate the onset of dementia in people who have higher levels of biomarkers. This highlights the need for doctors to consider kidney function when interpreting results of Alzheimer's biomarkers in the blood."
Researchers followed 2,279 participants with an average age of 72 who did not have dementia at the start. The participants underwent medical examinations and cognitive tests and had their blood tested for both kidney function and several Alzheimer's disease biomarkers: tau and amyloid beta proteins, neurofilament light chain proteins, and glial fibrillary acidic proteins.
Over an average follow-up period of eight years, researchers grouped participants based on kidney health: 1,722 had healthy kidneys (221 developed dementia), while 557 had poor kidney function (141 developed dementia). Reduced kidney function was associated with higher levels of most Alzheimer's biomarkers measured. These findings remained consistent even after excluding those who developed dementia during the study.
After adjusting for factors such as age, sex, and APOEe4—a genetic marker linked to a strong risk for Alzheimer’s—researchers found no link between poor kidney function and increased risk for developing dementia compared to those with healthy kidneys.
However, among individuals with impaired kidney function who also had elevated neurofilament light chain levels in their blood—a biomarker related to nerve cell damage—the risk of developing dementia was nearly double compared to those with good kidney health and high biomarker levels. Gasparini explained that this suggests "kidney health may influence the timing of dementia, but not the likelihood of developing dementia," particularly among people with high Alzheimer’s biomarker levels.
"When looking at these biomarkers in older adults, keeping an eye on kidney health may be more important than one might think," said Gasparini. "Monitoring kidney health may help clinicians better interpret these biomarkers and identify who might be at risk for faster disease progression."
The study's limitations include measuring Alzheimer’s-related blood biomarkers only once; therefore it could not assess how changes in kidney function over time might affect these markers. Additionally, most participants were highly educated urban residents from Sweden—so results may differ elsewhere.
