Quick Facts

• Impaired kidney function raises Alzheimer’s biomarker levels in blood by accumulating proteins normally filtered out
• People with both kidney problems and high biomarkers face nearly double the dementia risk compared to those with healthy kidneys
• Kidney function doesn’t independently increase dementia risk but may accelerate disease progression in at-risk individuals

A groundbreaking study reveals that poor kidney function can artificially elevate Alzheimer’s disease biomarkers in blood tests, potentially affecting diagnostic accuracy as these tests become standard medical practice.

Researchers tracked over 2,000 dementia-free adults with an average age of 72 and found that individuals with impaired kidney function had significantly higher concentrations of key Alzheimer’s proteins in their blood. The study, published in Neurology in January 2026, shows each small decrease in kidney function was linked to higher levels of neurofilament light chain, glial fibrillary acidic protein, and amyloid-beta proteins.

Dr. Francesca Gasparini of Karolinska Institutet in Stockholm explained the mechanism: “When the kidneys are not functioning properly, there may be higher levels of Alzheimer’s biomarkers in the blood.” The kidneys normally filter waste products and proteins from the bloodstream. When they work poorly, these proteins accumulate, including ones associated with Alzheimer’s disease.

The research found that people with stage 3 chronic kidney disease had mean neurofilament light chain levels of 46 pg/mL, compared to 25 pg/mL in those with healthy kidneys. Similar patterns emerged across multiple biomarkers used to detect neurodegeneration.

The clinical implications are significant. People with both impaired kidney function and high neurofilament light chain levels faced nearly double the dementia risk compared to those with healthy kidneys and similarly elevated biomarkers. However, kidney problems alone did not increase dementia risk.

“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,” Gasparini said.

The findings come as blood-based biomarker tests gain widespread clinical adoption. The Alzheimer’s Association recently published guidelines stating that blood tests with at least 90% accuracy for both sensitivity and specificity can substitute for more expensive PET scans or spinal fluid testing.

Hong Xu, assistant professor at Karolinska Institutet, noted the consistency of results: “We saw that lower kidney function was consistently associated with higher levels of several blood biomarkers. This pattern appeared both in unadjusted and adjusted analyses.”

A complementary meta-analysis of 93 studies involving over 62,000 participants from 21 countries confirmed these patterns. The analysis showed kidney function strongly affected blood biomarker concentrations but had minimal impact on biomarkers measured in cerebrospinal fluid.

The research suggests clinicians should monitor kidney health when interpreting Alzheimer’s blood tests. “Monitoring kidney health may help clinicians better interpret these biomarkers and identify who might be at risk for faster disease progression,” Gasparini said.

The study had limitations, including single-time biomarker measurements and a predominantly educated, urban Swedish population. Researchers emphasized more work is needed to understand how these findings should guide future diagnostic strategies.

Read more: The Overlooked Organ That Could Be Hiding Your True Alzheimer’s Risk