(WASHINGTON) -- The criteria for diagnosing Alzheimer's disease has been updated to incorporate new brain imaging and biochemical tests that could signal the disease before symptoms appear.
The update, which is the first in 27 years, stems from mounting evidence that the degeneration of nerves deep within the brain starts years or even decades before memory loss and other cognitive changes are noticeable.
"It is our hope that incorporating scientific knowledge gained and technological advances made over the past quarter century will improve current diagnosis, bring the field closer to earlier detection and treatment, and ultimately lead to effective disease-modifying therapies," Alzheimer's Association chief medical and scientific officer William Thies said in a statement.
The new criteria, published Tuesday in Alzheimer's & Dementia: The Journal of the Alzheimer's Association, open the door for research into the earliest stages of the disease and the development of drugs that may slow or stop the degenerative process before the damage is done. Their release follows a report that brain areas affected by Alzheimer's disease start shrinking up to a decade before symptoms appear.
The new criteria detail three stages of Alzheimer's disease: preclinical (before outward symptoms are visible); mild cognitive impairment (mild memory and thinking changes enough to be noticed but not debilitating); and dementia, or full-on Alzheimer's disease.
Some researchers call the diagnostic criteria revamp a necessary step -- one they hope will breathe new life into a field deflated by a string of negative drug trials.
But the tests used to spot features of preclinical Alzheimer's disease, many of which are still under development, are not yet approved by the Food and Drug Administration as diagnostic or prognostic tools, which means the new criteria will currently only be used for research purposes. And in the future, the cost of such tests and the meaning they carry will have to be carefully considered.
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