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Canadian Medical Association Journal
CMAJ - May 19, 1998 JAMC - le 19 mai 1998

Increase in Alzheimer's disease: Artifact or real?

CMAJ 1998;158:1271

See response from: S. Gauthier
Reading the excellent article "Alzheimer's disease: current knowledge, management and research," by Dr. Serge Gauthier and associates (CMAJ 1997;157[8]:1047-52 [full text / résumé]), I was struck by what to me is a remarkable feature of this disease, one that merited only 2 lines in the article: the incredible increase in its incidence over the past few years. Asthma, particularly in the very young, is the only other disease that has seen a comparable increase.

My concern is that our increasing life expectancy is being blamed for the increase in incidence when there may be some other cause. I remember being told as a student that the increase in cases of lung carcinoma was an illusion because the disease had previously been grossly underdiagnosed. We are now being told that Alzheimer's disease used to be passed off as "dementia" or "senile decay," but I wonder. In 12 years of general practice in England I encountered only one person with a condition resembling my wife's Alzheimer's disease, and in a town of 30 000 that woman was famous for her dementia. If Alzheimer's disease had been as common then as it is now, she would not have been exceptional. I also came across very few cases of "senile dementia."

The 1991 survey1,2 cited in the article reported that 28.5% of those over 85 years of age have Alzheimer's disease, but in nearly 25 years in rural practice, I met only 3 people with confirmed cases. Since then, I have worked mainly in walk-in clinics, and now there is scarcely a patient who hasn't a relative or a friend with this disease.

I can think of only 2 possible reasons: environment or nutrition (and the latter is unlikely because of the world distribution of Alzheimer's disease). My own feeling is that instead of worrying about PCBs and DDT, we should be looking at far more common pollutants, such as detergents, trace elements and radioactive waste, relative newcomers on the atmospheric scene.

Philip Rutter
St. Albert, Alta.

References

  1. Canadian Study of Health and Aging Working Group. Canadian Study of Health and Aging: study methods and prevalence of dementia. CMAJ 1994;150:899-10 13.
  2. Ebly EM, Parhad IM, Hogan DB, Fung TS. Prevalence and types of dementia in the very old: results from the Canadian Study of Health and Aging. Neurology 1994;44:1593-600.

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