Researchers propose new
Alzheimer's definition based on biology
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[April 10, 2018] By
Julie Steenhuysen
(Reuters) - Alzheimer's researchers have
proposed a radical change in the way the disease is defined, focusing on
biological changes in the body rather than clinical symptoms such as
memory loss and cognitive decline.
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The new research framework, released on Tuesday by the Alzheimer's
Association and the National Institute on Aging, is meant to provide
scientists with a common language for describing the disease in
research studies based on measurable changes in the brain that set
Alzheimer's apart from other causes of dementia.
"Much of the general public views the terms dementia and Alzheimer's
disease as interchangeable, but they are not," said Dr. Clifford
Jack of the Mayo Clinic in Rochester, Minnesota, who helped craft
the guidelines published in the journal Alzheimer’s & Dementia: The
Journal of the Alzheimer’s Association.
The proposed changes follow guidance announced earlier this year by
the U.S. Food and Drug Administration and the European Medicines
Agency to encourage the testing of new Alzheimer's medicines based
on biomarkers, rather than on clinical symptoms.
The moves would allow companies to test drugs in people before
symptoms appear, offering a better chance of intervening before the
disease has destroyed too many brain cells.
Under the proposed research framework, Alzheimer's would be
characterized by three factors: evidence of two abnormal proteins
associated with Alzheimer's - beta amyloid and tau - and evidence of
neurodegeneration or nerve cell death, all of which can be seen
through brain imaging or tests of cerebral spinal fluid. It also
incorporates measures of severity using biomarkers and a grading
system for cognitive impairment.
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The hope is that the new definition will help researchers pick
better subjects on which to test new Alzheimer's treatments, which
may help improve drug companies' search for treatments.
So far, experimental Alzheimer’s drugs have had a dismal track
record, with more than 100 failures, including most recently a
treatment from Merck, while Pfizer said in January it was quitting
the field.
Most of these drugs have focused on removing beta amyloid from the
brain. Recent imaging studies have shown that about 30 percent of
the people who have taken part in clinical trials for Alzheimer's
drugs did not have beta amyloid in their brains.
Jack said the new framework puts Alzheimer's more in line with other
diseases, such as hypertension or diabetes, and it will allow
researchers to study interventions that interfere with the
underlying changes that lead to Alzheimer's dementia.
(Reporting by Julie Steenhuysen in Chicago; Editing by Chris Reese)
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