Squeezing of blood vessels could contribute to decline in Alzheimer’s

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By Dr Laura Phipps | Friday 21 June 2019

A new study published by researchers at UCL has revealed that tightening of blood vessels in the brain in Alzheimer’s could play a key role in the disease. The research, published today in the journal Science, sheds new light on potential future approaches to treat the Alzheimer’s.

Research has shown that in the early stages of Alzheimer’s disease, the most common form of dementia, a number of abnormal changes start to occur in the brain. This includes the build-up of two proteins, called amyloid and tau, as well as a reduction in blood flow. As blood delivers oxygen and nutrients to brain cells, reducing the amount of blood flowing through the brain can have a negative impact on brain health.

Researchers at UCL set out to understand the interactions between amyloid and blood flow in the brain. The team studied slices of human brain in the laboratory, as well as mice bred to show features of Alzheimer’s disease, to reveal a mechanism by which the amyloid protein could restrict blood flow in the brain.

The findings suggest that amyloid triggers chemical signals to be released to brain cells called pericytes, which naturally control how tightly the small blood vessels in our brain are squeezed. When there is too much amyloid, such as in Alzheimer’s disease, pericytes squeeze too tightly, limiting the amount of blood that can flow around the brain.

The team then took tissue taken from biopsies of people with memory and thinking problems. They found that those people who had amyloid in their brain were also more likely to have blood vessels that were being bound more tightly by pericytes.

The researchers were able to use chemicals to loosen the grip of pericytes on blood vessels in brain slices in the laboratory. This suggests that such an approach could be a promising avenue in the search for new treatments for Alzheimer’s disease.

Dr Sara Imarisio, Head of Research at Alzheimer’s Research UK, said:
“We’ve known for some time that blood flow is restricted in the brain in Alzheimer’s, but this study tells us more about how. Teasing out the many complex processes that drive a disease like Alzheimer’s in the brain is key to developing effective treatments to stop it.

“This study adds to evidence that changes in blood flow in the brain could play an instrumental role in orchestrating damage in diseases like Alzheimer’s. Amyloid has long been a focus of efforts to develop new Alzheimer’s treatments but targeting the events downstream of amyloid may also be a promising approach. With a desperate need to develop effective medicines for Alzheimer’s disease, it’s important researchers understand the biology of the disease and leave no stone unturned in the search for life-changing treatments.”

About the author

Dr Laura Phipps