By Lee Bowman
Scripps Howard News Service
February 25, 2005
Axons connect brain cells to each other and carry electrical signals and chemical supplies throughout the brain. Thought, perception, memory and learning can occur when nerve impulses are carried along axons.
The pathways also extend to muscles and organs.
Alzheimer's is a degenerative condition that strikes the parts of the brain guiding memory and language, and generally becomes more common in people over age 60. However, it is not the result of normal aging. An estimated 4 million Americans suffer from the disease, for which there is no known cure.
Researchers at the University of California-San Diego studied both mouse models of Alzheimer's and brain tissue from human Alzheimer's patients who died when their disease was in its early stages.
They report Friday in the journal Science that they found abnormal amounts of proteins, cell parts and small cysts clogging the axons - like a rock in a garden hose - in both the mice and in the human brain tissue of early Alzheimer's patients more than a year before other symptoms were evident.
While scientists had known that transport within axons was blocked in late-stage Alzheimer's, the study is the first to show that the process begins early. This could help both in diagnosis and finding treatment for the disease.
It also marks the first evidence of a link between the two abnormalities that are the disease's hallmark - twisted, insoluble brain fibers called neurofibrillary tangles and amyloid plaques, excessive amounts of protein fragments that the body naturally produces.
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