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Guidelines for Diagnosing Alzheimer’s at Autopsy now Include Detecting Other Dementias

January 20, 2012 - It’s been 15 years since the last guidelines were established to diagnose Alzheimer’s disease at autopsy. Under the previous 1997 guidelines, a brain autopsy was typically conducted for people diagnosed with dementia, but only to determine whether Alzheimer’s disease was the underlying cause. Advances in neuropathology since then have revealed that diagnosing the cause of dementia at autopsy requires far more than a ‘black or white’ approach.

Research indicates that where biological changes exist for one form of dementia, there is likely to be at least one other disease process developing as well. At least half of all people with Lewy body dementia (LBD) have some of the neuropathological changes of Alzheimer’s disease as well, and vice versa.  The new criteria include guidelines to detect the presence of other neurodegenerative disease processes, like Lewy body disease, cerebrovascular disease, or frontotemporal disorders.

Not only are the new guidelines to be used for diagnosing specific biological processes at play in people who died with dementia, but also set the standard for examining all brains at autopsy. Recent advances in biomarkers (or biological indicators) have illuminated the fact that biological changes of Alzheimer’s disease may begin a decade or two before memory changes appear. Researchers are now able to identify a ‘pre-clinical’ stage to Alzheimer’s. Promising research indicates the same is true for Lewy body dementias, though more research is required to develop LBD biomarkers useful at the clinical level.

“The new guidelines are significant for advancing the understanding of LBD,” stated Dr. Thomas Montine, professor of neuropathology at Washington University and lead author of the new guidelines, “because of the recognition that Lewy body disease (the biological process itself) can occur in the apparent absence of clinical symptoms. These are guidelines for pathologists to interpret the significance of Lewy body disease on its own or in conjunction with other disease processes.”

The National Institute on Aging–Alzheimer’s Association guidelines for the neuropathologic assessment of Alzheimer’s disease were published online on January 18, 2012 in advance of print publication by Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.

For more information, visit the National Institute of Aging.