Researchers have found that two proteins which work in tandem in the brain’s blood vessels present a double whammy in Alzheimer’s disease.
Not only do the proteins lessen blood flow in the brain, but they also reduce the rate at which the brain is able to remove amyloid beta, the protein that builds up in toxic quantities in the brains of patients with the disease.
The work, described in the journal Nature Cell Biology, provides hard evidence directly linking two processes thought to be at play in Alzheimer’s disease: reduction in blood flow and the buildup of toxic amyloid beta.
The research makes the interaction between the two proteins a seductive target for researchers seeking to address both issues.
Scientists were surprised at the finding, which puts two proteins known for their role in the cardiovascular system front and center in the development of Alzheimer’s disease.
“This is quite unexpected,” said Berislav Zlokovic, M.D., Ph.D., a neuroscientist and a senior author of the study.
“On the other hand, both of these processes are mediated by the smooth muscle cells along blood vessel walls, and we know that those are seriously compromised in patients with Alzheimer’s disease, so perhaps we shouldn’t be completely surprised.”
For 15 years Zlokovic’s laboratory has focused on the molecular mechanisms regulating blood supply and the role of the blood-brain barrier in the development of Alzheimer’s disease. It’s not simply that reduced blood supply hurts brain cells by causing a shortage of oxygen and other nutrients. Rather, deterioration of blood flow seems to gum up the brain’s ability to remove toxic amyloid beta.
Normally, amyloid is picked up efficiently by blood vessels that then whisk the toxic trash away. But in Alzheimer’s disease, the system no longer is able to keep up with the body’s production of the substance. The molecular trash accumulates, and Zlokovic and others believe the buildup kills brain cells.