Amyloid-beta protein buildup, inflammation, tau accumulation and shrinking brain size — these are all factors that define neurodegenerative diseases like Alzheimer’s. It turns out that the brain’s blood vessels also play a role in these diseases, according to a new study.
Researchers have learned that things like exercise and a healthy cardiovascular system are typically good ways to prevent, or at least slow down, the progression of dementia. In a new study out of Massachusetts General Hospital (MGH), researchers honed in on blood vessels in the brain in particular, and how the health of these veins may help lower the risk of Alzheimer’s.
The study was published in Neuron and examined blood vessel pulsations in the brains of mice. These pulsations, known as vasomotion, typically assist in clearing harmful elements from the brain. In patients with Alzheimer’s or dementia, amyloid-beta protein tends to clump in the brain tissue and blood vessels, and isn’t properly cleaned up by the brain.
The researchers decided to study the potential of vasomotion as a way to “clean” out harmful substances from the brain. They did this using a fluorescent carbohydrate called dextran, which they injected into mice brains. They then tracked this brightly colored carbohydrate as the blood vessel pulsation, or vasomotion, pushed and cleared it out of the brain.
In mice with cerebral amyloid angiopathy — which involves amyloid protein building up in the brain’s artery walls — however, these pulsations were impaired. This left plenty of space for damaging elements to get stuck in the blood vessels. The researchers suggested that finding a way to keep vasomotion working could help clear out beta-amyloid from the brain.
“We were able to show for the first time that large dilations and contractions of vessels that happen spontaneously at an ultra-low frequency are a major driving force to clear waste products from the brain,” Susane van Veluw, an investigator in the department of neurology at MGH and an author of the study, said in a news release.
“Our findings highlight the importance of the vasculature in the pathophysiology of Alzheimer’s disease,” she added.
Fighting Alzheimer’s With Healthy Blood Vessels
Researchers have been aware of the link between the vascular and cardiovascular systems — the heart and connective blood vessels, which carry blood and oxygen throughout the body — and dementia for quite some time. Studies have pinpointed that high blood pressure is linked to an increased risk of developing dementia. Stroke has also been shown to double the risk of dementia.
There’s even a term for the type of dementia that occurs from damaged blood vessels: vascular dementia. Vascular dementia is caused by things like high blood pressure and stiffening blood vessels, which make it harder for blood to flow through the brain. Some experts argue that nearly half of dementia cases are caused by negative vascular changes in the brain.
One of the best ways to prevent poor vascular health, and the subsequent cognitive decline, is to simply exercise. Moderate to rigorous physical activity, several days a week, can do wonders for the brain. Activities like walking, running or even skiing have been shown to lower the risk of vascular dementia.
But what if researchers also found a way to boost that blood vessel pulsation, or vasomotion, to help out in fighting off rogue amyloid-beta proteins? The researchers of the latest study believe there may be something there to continue investigating.
“If we direct therapeutic strategies towards promoting healthy vasculature and therefore improve clearance of amyloid-beta from the brain, we may be able to prevent or delay the onset of Alzheimer’s disease in the future,” van Veluw said.