More Than the Epidemiology of Alzheimer's Disease: Contributions of the Canadian Study of Health and Aging

Objective: To highlight contributions to knowledge made by the Canadian Study of Health and Aging (CSHA). Method: The CSHA began in 1991, with follow-ups in 1996 and 2001. It was national in scope, with 18 study centres and a coordinating centre. It included 10 263 participants; of these, 9008 were in the community, and 1255 were in institutions. In each phase, community participants were screened for cognitive impairment, and where appropriate, cognitive status was determined by a detailed clinical examination. Data on possible risk factors for dementia were collected at baseline. Data on caring for people with dementia were collected in each phase. Results: The prevalence of dementia was established at 8% of those aged 65 years and over; incidence (new cases each year) was about 2%. Cognitive impairment not dementia (CIND) was more than twice as common as dementia. Factors affecting the risk of institutionalization, mortality, and the health of caregivers were examined. The costs of dementia were conservatively estimated at $3.9 billion in 1991. Risk factors for Alzheimer's disease (AD) and vascular dementia are presented; it is noteworthy that physical activity appeared to protect against all forms of cognitive decline, particularly for women. Clinical contributions include the development of norms for several neuropsychological tests. Other topics include the health of those with CIND, predicting dementia, medication use, frailty and healthy aging, and urinary incontinence. Conclusion: The CSHA has contributed substantially to knowledge of the epidemiology of dementia, including AD, and to many other topics relevant to seniors' health.