Early Detection of
Alzheimer's Disease May Involve Protein - A-beta-Star May Put Neurons to
Sleep Not Kill Them - Treatment May Follow
Researchers at the University of Minnesota say they have identified a
possible future target for therapies to defeat Alzheimer’s disease (AD)
before it causes irreversible damage. The identifying characteristic
for AD is numerous insoluble clumps, or plaques, composed of a specific
protein called amyloid-beta (A beta).
Researchers had thought that these plaques caused AD, but they were
mistaken. According to Karen Ashe of the University of Minnesota,
“About four years ago, we realized there was no correlation between the
amount of plaque and the amount of memory dysfunction.” This caused
Ashe, a professor of neurology and neuroscience and director of the
University's Center for Memory Research and Care, to start focusing on
The researchers notice abnormal brain scans of some people that were
genetically predisposed to AD. The abnormalities were very subtle but
it did suggest changes in the way the brain operates long before nerve
cells begin to die. Ashe chose one such mutant gene, which causes the
brain to produce A beta in large quantities-a close approximation to the
increased outputs of A beta that occur in normal aging.
One of Ashe’s postdoctoral lab fellows, Sylvain Lesne, noticed that
these A beta molecules began to clump together in aggregates of three,
six, nine or 12. This led the team to investigate which clumps were
most capable of causing memory problems. It turned out the clumps of 12
A-beta molecules (A-beta_star) were the most potent in causing memory
loss in rats.
Interestingly these A beta molecules don’t seem to kill the neurons.
According to the researchers, the damage was not permanent. After 10
days without injections of A-beta-star, the rats regained their memory.
As Ashe puts it, the A beta protein, even A-beta-star, didn't kill
neurons-it just put them to sleep.
The researchers have developed a blood test to detect A-beta-star. They
also plan to search for drugs that help AD patients by preventing the
formation of A-beta-star that would eventually lead to an interference
with neuron function. Her work appears in the Journal Nature and will
hopefully lead to a treatment for the 4.5 million Americans living with
Alzheimer's disease, and the expected 14 million in the next 20 years.
By Dan Wilson
Books on the Mind
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