Group Pushes New Guidelines for Alzheimer's Disease Testing

July 13, 2010— -- HONOLULU -- Tests involving brain imaging and screening proteins find in the in cerebrospinal fluid (CSF) can now be used clinically in diagnosing Alzheimer's disease, according to new guidelines proposed by a working group from the National Institute on Aging and the Alzheimer's Association.

If adopted, the guidelines would be the first major update in diagnostic criteria for Alzheimer's disease since 1984.

The working group, chaired by Dr. Guy McKhann of Johns Hopkins University in Baltimore, presented its proposal here at the International Conference on Alzheimer's Disease (ICAD), seeking the first outside comment from the medical community.

The proposal said "probable Alzheimer's disease" can be diagnosed in patients with clinical dementia in the absence of a documented long-term decline in cognitive function if the results of any of five specific imaging or CSF tests are positive.

The proposed guideline would still reserve a definitive diagnosis for patients after they died, on the basis of autopsy findings.

Previously, diagnosis of probable Alzheimer's disease was based solely on clinical presentation, with other potential causes of dementia such as cerebrovascular or Parkinson's disease ruled out. It also established age cutoffs and implied a requirement for extensive neuropsychological testing.

"These criteria have some shortcomings that need to be addressed," the working group wrote in its report. "Some relate to lack of knowledge at the time of the development of the original criteria. Others relate to the vast expansion of our knowledge of the biology of [Alzheimer's disease]."

Besides the new science on biomarkers and imaging of brain abnormalities, other advances include better ways to distinguish dementias with different causes. And it is now understood that memory impairment is not "always the primary cognitive deficit in all patients" with Alzheimer's disease, the working group indicated.

But one prominent Alzheimer's disease researcher contacted by MedPage Today and ABC News called the inclusion of imaging and biomarker data in diagnosis at this point "a step in the wrong direction."