A new study from the University of Cambridge has uncovered a surprising link between the brain’s waste-clearing system and the risk of developing dementia.
The study suggests that when this system doesn’t work properly, it may help explain why poor sleep and problems like high blood pressure raise the chances of getting dementia later in life.
### What is the Glymphatic System?
The waste-clearing system in the brain is called the glymphatic system. Discovered only in 2012, it works by moving a clear liquid called cerebrospinal fluid (CSF) through the brain. This fluid flows along tiny channels surrounding blood vessels, collecting waste products and harmful substances. It then carries them away, keeping the brain clean and healthy.
In diseases like Alzheimer’s, toxic materials build up in the brain — such as amyloid plaques and tau tangles. These substances are believed to play a big role in memory loss and cognitive problems. If the glymphatic system doesn’t clear these toxins effectively, the brain can get overwhelmed, leading to damage over time.
### Dementia and Blood Vessel Health
Vascular dementia is another common type of dementia, caused by reduced blood flow in the brain. The main cause is cerebral small vessel disease, which affects tiny blood vessels.
Research has shown that people with both Alzheimer’s and small vessel disease are more likely to exhibit symptoms of dementia than those with just one of these problems.
The researchers wanted to know whether small vessel disease and other heart-related risk factors harm the glymphatic system, which in turn could increase dementia risk.
### New Ways to Study the Glymphatic System in Humans
Until recently, scientists could only study the glymphatic system in mice. But thanks to new types of MRI brain scans and advanced computer tools, researchers can now study it in people.
The research team used advanced machine learning techniques to analyze MRI brain scans from nearly 40,000 adults in the UK Biobank. They identified three markers that indicate how well the glymphatic system is functioning:
– How water moves along the brain’s blood vessels
– The size of the part of the brain where cerebrospinal fluid is made
– How fast the fluid flows into the brain
### Key Findings
The results showed that people with poor glymphatic function had a higher chance of developing dementia within the next ten years.
They also found that heart health problems, such as high blood pressure, worsened glymphatic function by causing small vessel disease.
### Why This Matters
This study provides a possible explanation for why poor heart health increases the risk of dementia. It also points to new ways to help prevent dementia.
For example, improving sleep could help the glymphatic system clear out waste more effectively, since this system works most actively during sleep.
Another potential approach is to develop medicines that support the glymphatic system directly. Treating high blood pressure may be especially important. Earlier research, like the SPRINT MIND trial, has shown that lowering blood pressure can reduce the risk of cognitive decline. This new study supports that by demonstrating how high blood pressure might damage the brain’s cleaning system.
### Takeaway
In the end, this research highlights how important it is to take care of both your heart and your sleep. By doing so, you might also be helping your brain stay healthy for longer.
As Professor Hugh Markus from Cambridge explained, controlling blood pressure and avoiding smoking are simple steps that could improve glymphatic system function — possibly lowering the chances of getting dementia.
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If you are concerned about dementia, also consider reading studies about a common drug for constipation linked to higher dementia risk, and findings showing a link between heartburn drugs and increased dementia risk.
This study is published in *Alzheimer’s & Dementia*.
https://knowridge.com/2025/11/study-finds-the-key-to-preventing-dementia-2/