Expansion of the definition of dementia – good or bad?

Dr. Gordon blogs:


Dr. Michael Gordon, one of the longest serving geriatricians in Canada, and currently medical program director of Palliative Care at Baycrest, weighs in on the new U.S. guidelines. Dr. Gordon is co-author with other Canadian scholars on a paper that addresses the new guidelines, to be published in the journal, Alzheimer’s and Dementia.

American dementia experts have decided to expand the “dementia” definition to include a “pre-clinical” stage. This new definition is not without controversy. It’s based on the best estimates of dementia’s causative mechanisms and the tools that we currently have to identify individuals with the defined “biomarkers” such as specific structural findings on special imaging procedures of the brain and proteins in the cerebrospinal fluid (the fluid that surrounds and protects the brain). These biomarkers might indicate a higher likelihood of going from an apparently “normal” state of health to one in which early and then full-blown dementia will likely develop.

The idea is aligned with efforts to identify as early as possible those at higher risk for developing dementia and then determine which early interventions might postpone or prevent its progress. The model mimics that used for cardiovascular disease (CVD) in which, over the years, the field of medicine has accumulated sufficient knowledge to identify “risk factors” (e.g. hypertension, elevated blood lipids, sedentary life style, smoking) and then determine the impact of interventions such as exercise, diet, discontinuation of smoking, and medications to control, for example, hypertension and elevated lipids. This approach has significantly reduced the number of people afflicted with CVD — a testament to the beneficial effects of such interventions.

Whether a comparable pre-clinical diagnostic approach for dementia will be beneficial is the million dollar question. Can we detect those at risk of developing dementia (before symptoms) and then decrease their risk through various research-based experimental interventions?

A Canadian Task force has explored some of the potentially negative ramifications of the pre-clinical approach. The report will be published in the May issue of the journal Alzheimer’s and Dementia. Among the concerns noted in the report: the psychological result of labeling someone as being at risk of developing dementia; the implications for insurability for health care, travel, disability and long-term care insurance; the impact on the stability of family relationships and the exposure of people potentially at risk, but not certain to get the disease; and the implications of starting various interventions that might include potent and potentially toxic medications.

Although the potential for research to collect evidence-based data on the efficacy of pre-clinical interventions is very appealing, the potential for harm to the screened population might be serious. I strongly recommend that the risks be weighed very carefully before large-scale screening and labeling is undertaken by practicing physicians and researchers.