Brain Scans for Diagnosing AD

Contributed by: Dennis Fortier, President, Medical Care Corporation

In this cleverly written, but wantonly provocative article in the Forbes blog “The Science of Business”, it takes the author only 53 words to completely mislead his audience.

In his attempt to find controversy in a straight forward advance, there are two areas where the author has blurred the truth. First, the guidelines he references, which define a very early stage of Alzheimer’s, are not intended for physicians seeing patients but for researchers doing scientific work in a laboratory. Second, adoption of a new definition by the research community has nothing to do with approval of a diagnostic process, like brain scans, that physicians would use in diagnosing patients.

Here is a more sensible summary of the situation than the one Robert Langreth has thrust upon his readership:

An expert panel, convened by the NIH and the National Alzheimer’s Association, has drafted new guidelines for defining Alzheimer’s disease. These new guidelines are intended to correct a major deficiency in the existing guidelines that were established in 1984.

Original Guidelines

The original guidelines suggest that Alzheimer’s disease is not present until the subject has dementia. Recall that the term “dementia” defines a state of impaired thinking that is so severe that subjects can no longer care for themselves without human assistance. This means that, under the old definition of Alzheimer’s disease, a subject with accumulating amyloid in their brain, and clear symptoms of memory loss, does not have Alzheimer’s disease until their impairment progresses to the point where they become dependent on others.

Obviously, this makes no sense. We wouldn’t set some late stage criteria, like blindness, before diagnosing diabetes, and we shouldn’t do so for Alzheimer’s disease. It is this old and problematic definition that has primary care physicians around the world, watching patients with memory loss, and doing nothing to treat the problem until the patient becomes demented. Only then can they consider diagnosing Alzheimer’s disease and prescribing a very late and predictably ineffective treatment regimen.

Proposed Guidelines
The new guidelines cover 3 stages of the disease:
1) AD Dementia – the definition of this progressed state is largely consistent with the original language used to describe the entire disease continuum.
2) Mild Cognitive Impairment due to AD - an earlier stage of the disease. This definition will facilitate timely intervention for patients with memory loss who are not yet demented.
3) Pre-Clinical AD - the earliest and least certain stage. It includes the period when pathological changes are underway but there are no outward symptoms of disease. These guidelines, which are the ones cited by Langreth, are clearly and expressly intended for researchers, not physicians.

Adoption into Clinical Practice
Finally, there is really no need for alarm that adoption of new definitions in the research community will unleash massive, premature change in clinical practice. Langreth makes a dangerous, conceptual leap based on the word “approved”. He states “…once a plaque brain scans gets approved the next step will be that aggressive doctors will start using it in patients with the slightest sign of fleeting memory or cognitive problems”. Lets be clear about this; adoption of new language by an expert panel has absolutely nothing to do with the FDA’s possible, eventual approval of a diagnostic test that can be used in clinical practice. The author implies a close association between these discrete events that is not justified. It is pure artistic license and sensationalism.

These are the kinds of articles that perpetrate the public’s nihilistic attitudes toward Alzheimer’s disease and prevent the kind of constructive discourse that will help us tackle the problem in a meaningful way. It is really a shame that the credibility of the Forbes imprimatur was lent to this misleading report on such a clear step forward for AD research.

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