People with reduced kidney function may have higher levels of several blood markers commonly used in Alzheimer’s disease research, according to a large new review published in the Journal of the American Society of Nephrology.
The findings suggest that kidney health could influence how doctors and scientists interpret blood tests related to dementia.
Researchers analyzed results from 93 previous studies involving more than 62,000 adults across 21 countries.
They focused on whether kidney function — typically measured by a value called estimated glomerular filtration rate (eGFR) — was linked to levels of key Alzheimer’s-related biomarkers in blood and cerebrospinal fluid.
These biomarkers included amyloid-beta, tau proteins, neurofilament light (NfL), and glial fibrillary acidic protein (GFAP), all of which are associated with brain changes seen in Alzheimer’s disease and other forms of dementia.
The team found a consistent pattern: people with lower kidney function tended to have higher levels of several biomarkers in their blood.
This relationship held true even after researchers accounted for other health factors.
For example, each small drop in kidney function was associated with slightly higher levels of NfL, GFAP, and a form of amyloid protein known as amyloid-beta 40.
However, when the scientists looked at biomarkers in cerebrospinal fluid — the liquid surrounding the brain and spinal cord — the results were less clear, and no strong link with kidney function was found.
The findings are important because blood tests for dementia are becoming more common in both research and clinical care.
If kidney disease can raise these biomarker levels independently of brain disease, it could potentially lead to misleading results. In other words, a person with poor kidney function might appear to have higher dementia risk based on blood tests alone, even if their brain is not significantly affected.
Researchers say the results highlight the need to consider overall health — especially kidney health — when interpreting Alzheimer’s blood tests. They also emphasize that more research is needed to understand why kidney function influences these biomarkers and how doctors should adjust for this effect in future screening and diagnosis.
Although the study does not show that kidney disease causes dementia, it underscores the close connection between different organs in the body. Maintaining kidney health through good hydration, balanced nutrition, blood pressure control, and diabetes management may not only protect the kidneys but could also help ensure more accurate assessment of brain health in later life.
As blood tests for Alzheimer’s disease move closer to routine use, understanding factors that influence the results will be essential for accurate diagnosis and treatment planning.
