Abnormal constricting of tiny blood vessels in the brain may contribute to Alzheimer's disease by cutting blood flow to brain cells, a study suggests.
The research involves beta amyloid, a protein found in deposits in the brains of people with Alzheimer's. Scientists have studied whether beta amyloid plays a role in Alzheimer's by killing brain cells, but the new work looked for its effect on blood vessels.Scientists worked with a form of beta amyloid that is normally found in the blood of healthy people. They found that in laboratory dishes, it created damaging molecules called free radicals when it came in contact with cells lining the blood vessels. These radicals made blood vessels constrict.
In Alzheimer's, some brain cells may be damaged by a reduction in their blood supply when the tiny vessels that feed them become constricted, and the free radicals themselves may cause further damage, said researcher Dr. Michael Mullan of the Roskamp Laboratories at the University of South Florida.
If blood vessels do play a role in Alzheimer's, it should be easier to deliver drugs to them than to brain cells, he said.
Mullan and colleagues published the work in Thursday's issue of the journal Nature.
Mullan said that since beta amyloid is found normally in the bloodstream, there must be some unknown substances in the blood or blood vessels that normally prevent the constriction and the generation of free radicals.
Zaven Khachaturian, director of the Alzheimer Association's Ronald and Nancy Reagan Research Instititute, called the work provocative. But he cautioned that the work was done in isolated blood vessels in laboratory dishes.