New Guidelines Set for Alzheimer's Disease Post-Mortem Diagnosis

November 16, 1996

A group of 17 leading scientists from around the world agreed upon recommendations to revise the criteria for diagnosis of Alzheimer's disease at autopsy. As a result, neuropathologists now will have access to standardized and improved criteria to distinguish different forms of Alzheimer's disease and related dementias. More rigorous pathological studies will greatly aid researchers in their understanding of the disease and may accelerate the pace of Alzheimer's research.

The meeting, co-sponsored by the National Institute on Aging (NIA) and the Alzheimer's Association Ronald and Nancy Reagan Research Institute, met on November 13 and 14 to reevaluate existing guidelines for post-mortem diagnosis of Alzheimer's, and make recommendations to improve those procedures.

"The field of Alzheimer's research has blossomed since the existing criteria were developed in 1983. We need to refine our diagnostic procedures based on new knowledge related to the distribution of plaques and tangles in the brain," said Creighton Phelps, Ph.D., Director, Alzheimer's Disease Centers Program at the NIA.

"For researchers, knowledge of Alzheimer's disease gleaned through autopsy findings can give insight into the workings of the disease in living people, and provide the first steps in developing treatments," said Zaven Khachaturian, Ph.D., director of the Reagan Institute. "It is therefore critically important to have standards that everyone follows so that researchers can effectively exchange and compare information."

The panel agreed to a number of general principles, and developed a series of specific recommendations. One of the general principles defined high, moderate, and low likelihood of Alzheimer's disease based on the presence in the brain of different amounts of each of two characteristic lesions, known as neuritic plaques and neurofibrillary tangles. Previously, only the density of plaques was used as a diagnostic marker at autopsy.

The group also recommended that pathologists look for signs of Alzheimer's disease in a number of specified areas of the brain, that all lesions found in the brain should be noted at autopsy, and that all diagnoses present in any one patient, for example Alzheimer's disease and/or Lewy body dementia, should be specified. This expanded analysis recognizes that cognitive impairment often is attributable to more than one cause.

The panel called for a validation study of the new criteria. The Reagan Institute and the NIA will continue to convene this Working Group at regular intervals to review and refine the recommendations.

The first standard diagnostic criteria for Alzheimer's were developed in 1983 and published in 1985 by a group led by Khachaturian, who was then at the NIA. CERAD, the Consortium to Establish a Registry for Alzheimer's Disease, subsequently developed a set of diagnostic standards.

The panel's full recommendations, along with a complete set of preliminary position papers submitted by panel members, will be published in a future special issue of the journal Neurobiology of Aging.

Alzheimer's disease currently afflicts over 4 million Americans. Since definitive diagnosis of Alzheimer's is available only at autopsy, use of precise diagnostic criteria are important to help minimize uncertainty in diagnosis.

The NIA, a component of the National Institutes of Health, leads the Federal effort supporting basic, clinical, social, and behavioral research on Alzheimer's disease, aging, and the special needs of older people. The Alzheimer's Association is the only national voluntary health organization dedicated to conquering Alzheimer's disease through research and providing support and assistance to those afflicted with the disease and their caregivers.

For more information on Alzheimer's disease, contact the NIA at 1-800-438-4380 or the Alzheimer's Association at 1-800-272-3900.
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NIH/National Institute on Aging

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