A major study led by the University of Cambridge has revealed that problems with the brain’s waste clearance system may explain why some people develop dementia—especially those with poor sleep or high blood pressure.
These findings could lead to new ways of preventing or treating dementia, one of the biggest health challenges of our time.
Dementia is a group of diseases that affect memory, thinking, and behavior. Alzheimer’s disease is the most common form, followed by vascular dementia.
While we’ve known that toxic substances like amyloid plaques and tau tangles build up in the brain and cause damage, scientists have long wondered why this happens in some people but not others.
The answer may lie in a system called the glymphatic system. This system, discovered only in 2012, acts like a cleaning crew for the brain. It uses cerebrospinal fluid (CSF)—a clear liquid that surrounds the brain—to flush out waste through tiny channels along blood vessels.
These channels are called perivascular spaces. The fluid then drains the waste out of the brain, helping to keep it healthy.
In people with dementia, this cleaning system may not work properly. The study, published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, looked at brain scans from 40,000 adults in the UK Biobank, a major health study.
It’s the first time researchers have been able to measure the glymphatic system in humans at such a large scale.
To do this, the research team used artificial intelligence and machine learning to analyze MRI scans.
They looked for signs of poor glymphatic function, such as slower CSF flow or changes in the choroid plexus, the part of the brain that produces CSF. One key measurement was DTI-ALPS, which tracks how water moves through the perivascular spaces.
They found that people with signs of poor glymphatic function were more likely to develop dementia over the next 10 years. In fact, three specific biomarkers from the brain scans were good predictors of future dementia risk.
The study also showed that common cardiovascular risk factors—like high blood pressure and smoking—damaged the glymphatic system.
These factors were linked to small vessel disease in the brain, which blocks blood flow and seems to make it harder for the brain to clean itself. When this happens, harmful substances like amyloid and tau can build up more easily.
These findings help explain why people with heart problems or poor sleep are more likely to get dementia. Sleep is especially important because the glymphatic system is most active during deep sleep. Disrupted sleep may prevent the brain from clearing out waste properly.
There’s hope, though. Since we already know how to treat conditions like high blood pressure, we may be able to protect the glymphatic system and reduce the risk of dementia.
For example, a recent study found that keeping systolic blood pressure under 120 mmHg led to a 20% drop in the chance of cognitive decline or dementia.
Professor Hugh Markus, who led the study, believes that focusing on heart health could help keep the brain’s cleaning system working well. Simple steps like treating high blood pressure and quitting smoking could make a big difference.
The study was funded by the British Heart Foundation and supported by the National Institute for Health and Care Research. Experts say the results open exciting new doors for research and offer hope for better dementia prevention.
If you care about dementia, please read studies about Common drug for constipation is linked to higher dementia risk and findings of Scientists find link between heartburn drugs and increased dementia risk.
For more about dementia, please read studies about Scientists find a drug related to Viagra may help treat vascular dementia and findings of link between body inflammation and dementia risk.
The study is published in Alzheimer’s & Dementia.
Copyright © 2025 Knowridge Science Report. All rights reserved.
