Most people know that age is the biggest risk factor for dementia, but scientists are learning more about how other parts of the body can also affect brain health.
A new study from Karolinska Institutet in Sweden has found that kidney problems—specifically, the presence of a protein called albumin in urine—may increase the risk of developing dementia.
Albumin is a protein that should stay in the blood. When it appears in the urine, it’s a sign that the kidneys are not working properly.
This condition is called albuminuria. While it has long been used to track kidney health, the new research shows that it could also be an early warning sign for brain diseases like dementia.
The study, published in the Journal of Internal Medicine, followed more than 130,000 older adults in Stockholm who were all over the age of 65 and did not have dementia at the start of the study.
Researchers tracked their health over four years, and during that time, about 7% of the participants developed dementia.
After adjusting for kidney function and other health factors, the researchers discovered a clear link between albumin in the urine and a higher risk of dementia.
People with moderate levels of albumin (30–299 mg/g) had a 25% greater risk of developing dementia.
For those with even higher levels (300 mg/g or more), the risk jumped to 37% compared to people with normal levels.
The risk was especially strong for vascular dementia, a common type of dementia that happens when blood flow to the brain is reduced, often due to stroke, high blood pressure, or diabetes. It was also high for mixed dementia, which includes both vascular problems and changes seen in Alzheimer’s disease.
Why does kidney health affect the brain?
According to Dr. Hong Xu, one of the lead researchers, it’s because both the brain and the kidneys rely on very small and delicate blood vessels. Damage to the blood vessels in the kidneys can be a sign that similar damage is happening in the brain.
One key part of the brain’s protection system is the blood–brain barrier. This barrier keeps harmful substances in the blood from reaching the brain. But if it becomes damaged—just like the kidney filter that leaks albumin into the urine—it can let dangerous molecules enter the brain.
Over time, this can lead to inflammation, damage to blood vessels, and the buildup of proteins linked to dementia.
The researchers say their findings highlight the importance of checking for albumin in urine, especially for people who already have conditions like high blood pressure, diabetes, heart disease, or kidney problems. By catching albuminuria early, doctors might be able to take steps to lower the risk of dementia or delay its onset.
In short, this study adds to the growing evidence that what’s happening in the kidneys may offer important clues about the brain. Taking care of your kidneys could be one more way to protect your brain health as you age.
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