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    New Study Sheds Light on Progression of Alzheimer's Disease


    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 are apparent.

    "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."

    Vital Information:

    • 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.
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