New Study Sheds Light on Progression of Alzheimer's Disease
WebMD News Archive
Researchers measured the amount of two different kinds of beta-amyloid
proteins in five regions of the brain and found that patients who hadn't had
Alzheimer's had lower levels than those who did have Alzheimer's. The average
levels of both proteins were generally higher in patients who had in life had
more severe Alzheimer's.
When the researchers looked at the tau protein tangles in the front part of
the brain, a part of the brain involved only late in the disease's progression,
they found increases in both beta-amyloid proteins came before the formation of
the tangles, and that these increases occur before many symptoms of Alzheimer's
"There has always been a lot of uncertainty about which of the many
changes are the earliest and the most relevant for causing Alzheimer's, and
which occur after the fact," Allan Levey, MD, PhD, tells WebMD. "It is
still not absolutely clear; this study doesn't settle it completely, but it
just gives more reasons for thinking that amyloid is important." Levey is a
professor of neurology and director of the Alzheimer's Disease Center at Emory
University in Atlanta.
"[The study] does provide more reason to study early changes that occur
in the brain in Alzheimer's disease, and I think it will prompt further study
in the role of tangles vs. amyloid in other brain regions," says Levey.
"Ultimately it may help in the development of treatments."
- The brains of Alzheimer's patients contain plaques made of beta-amyloid
protein found outside the cells and contain tangles of a protein called tau
found inside the cells.
- There has been a debate among the scientific community about which protein
causes Alzheimer's, if one causes the other, and which one develops first.
- New research shows that the beta-amyloid protein plaques are formed first
and develop even before symptoms of the disease are present.