What Do We Mean By a "Disease of Aging" Anyway?

I noticed a paper today whose abstract provides a good cross-section of the never-to-be-settled debate over what exactly constitutes a disease of aging, versus the other descriptive categories for the things that go wrong with the human body over time:

In a recent book, Dr. Peter Whitehouse describes Alzheimer's disease as a myth that cannot be separated from aging and, as such, the "disease" is simply an accelerated brain aging. While it is factually true that the aging brain and Alzheimer's disease are on a pathological continuum, this is true only in the most general sense - that is, the quantities of plaques and tangles in the brain.

It is well known that standard pathological criteria do not address such factors as the nature and onset of clinical signs, kinetics of disease progression, and presence or absence of age-related co-morbidities such as hypertensive cerebrovascular disease and diabetes mellitus. Clearly, a 68 year old patient who dies of pneumonia while in a vegetative state after a four year history of progressive dementia, and who is found later to have met Alzheimer's disease criteria at autopsy, has a "disease." Further, it would be an offense to the patient's family and to the condition itself to suggest that this mind-destroying process, occurring at an age where many individuals of the same age are vacationing and/or working New York Times crossword puzzles, is simply a manifestation of advanced age.

Moving Alzheimer's disease to an aging disorder may take some of the stigma and fear from the disease, and for this, Dr. Whitehouse is commended; however, such well intentioned motives should not lead us down the path of minimizing Alzheimer's disease and "lumping" a condition into a category before that condition is adequately understood. It might also be noted that the term "Alzheimer's disease," suggested first by Emil Kraepelin, was justified because of early age at onset, and clinical signs that differed from "dementia senilis." So perhaps Dr. Whitehouse is confusing Alzheimer's disease as it was originally intended, with senile dementia in the very old - a term and an age group that is more in line with the idea that "Alzheimer's disease" is a manifestation purely of advanced age.

If we lived in a world in which the market for research and development of medicine was completely free and unregulated, this sort of debate over nomenclature would be an amusing side-show to the process of developing methods of prevention and cure. Unfortunately, all medical research in the US operates in the shadow of the FDA, and treatments for aspects of aging that are not clearly defined and recognized by the slowly-turning wheels of bureaucracy will not be approved for use. Those potential treatments therefore won't be funded for development, and basic research in that area will be lacking - few people are willing to embark upon work that will not attain recognition or profit, and fewer fund it. In this way the FDA and similar regulatory bodies suppress innovation before it has even started.

That is the context for the quote above: defining a condition away from being a "disease" is an attack on funding legitimacy for many, given the way in which the FDA's pronouncements determine directions in research. It's a pretty sad situation all round.

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