Why poor sleep and high blood pressure increase the risk of dementia
Scientists have discovered problems in the brain’s ability to clear toxins and suggest this may be why poor sleep and high blood pressure increase the risk of dementia.
In a healthy brain, the glymphatic system clears poisons and waste. It carries cerebrospinal fluid (CSF) (the clear fluid that buffers the brain) from the brain through small channels around blood vessels. This fluid collects toxins and flushes them out of the brain, keeping the brain clean and healthy.
However, if this process does not work properly, it can increase the risk of dementia later in life. Decreased sleep and cardiovascular problems affect how well the glymphatic system works, according to a study conducted by researchers at the University of Cambridge.
Lead author Hui Hong said: “We already have evidence that small vessel disease in the brain accelerates diseases such as Alzheimer’s, and now we have a possible explanation why.
“Impairment in the glymphatic system will likely impair our ability to clear the brain of the amyloid and tau that cause Alzheimer’s disease.”
Alzheimer’s disease, the most common type of dementia, is linked to the buildup of amyloid and tau proteins in the brain. In Alzheimer’s disease, tau circulates inside neurons in the brain as amyloid adheres to the brain and forms plaques, eventually causing brain cells to die; both lead to the onset of dementia symptoms.
Another common form of dementia is vascular dementia, which is caused by reduced blood flow to the brain and affects around 180,000 people in the UK, according to the NHS.
The researchers wanted to see whether cerebral small vessel disease and other cardiovascular risk factors damage the glymphatic system, which in turn increases the risk of dementia.
Study published in the journal Alzheimer’s and Dementia: Journal of the Alzheimer’s AssociationIt used artificial intelligence to analyze MRI scans of nearly 40,000 adults in the UK Biobank.
The analysis revealed several risk factors that predict dementia, including how well CSF flows to the brain.
Further analysis showed that several cardiovascular risk factors impair glymphatic function, resulting in increased risk of dementia. This was caused in part by cerebral small vessel disease, which can be seen on MRI scans.
Researchers have suggested several ways to reduce the risk of dementia. One of them is improving sleep.
This is because sleep plays an important role in glymphatic function, and the study authors suggested that disrupted sleep patterns impair the brain’s ability to clear toxins and waste.
Another approach is to treat vascular problems such as high blood pressure, which have been shown to increase the risk of small vessel disease and vascular dementia.
Professor Markus, who leads the stroke research group at the University of Cambridge, said: “At least a quarter of the risk of dementia is due to common risk factors such as blood pressure and smoking.
“If these impair glymphatic function, we can intervene. Treating high blood pressure or encouraging people to quit smoking may be an achievable way to help the glymphatic system work better.”
It is estimated that there are currently 982,000 people with dementia in the UK, but more than a third of people with the condition have no diagnosis.
