The Canadian Study of Health and Aging was a complex undertaking that faced management challenges not encountered by smaller-scale projects. The study followed 10,263 elderly people in 18 study centers spanning six time zones; it was administered in two languages, and over 70 investigators were involved. The data collected from each participant were not fixed, but varied according to the results of earlier testing. The data could include a screening interview, a self-completed risk factor questionnaire, an interview with a relative, a clinical examination, neuropsychological testing, blood samples, and neuroimaging.This report describes the approach taken to organize the study, to track participants, and to monitor adherence to the study protocol. It also describes the human organizational aspects, including systems for staff training, for communicating among study centers, and for coordinating the publication of results. The discussion proposes some guiding principles for administering multicenter studies.

The first wave of the Canadian Study of Health and Aging (CSHA) constituted a large health survey of a representative sample of elderly Canadians. Other Canadian surveys from the same era provided equivalent figures, and the present report compares the results of 6 surveys on a variety of health indicators. Agreement was close on self-reported chronic health conditions, adequate for several indicators of functional limitation, but was lower for overall self-ratings of the impact of health problems on day-to-day life. Using the CSHA data to compare alternative operational definitions of frailty, a definition based on ADL limitations appeared to offer an underestimate; addition of IADL questions or cognitive limitations provided figures that appeared more plausible. Survey estimates of chronic health conditions appear consistent, as are estimates of certain ADL disabilities. Care must be taken with interpreting more subjective reports, while prevalence of frailty varies considerably according to the definition used.

Correlates of nonparticipation in the community interview component of the Canadian Study of Health and Aging and their impact on bias in the results were analyzed. Characteristics of study subjects, their habitats, and encouragement techniques were analyzed to indentify correlates of variation in response rates across the 18 study centers. Refusal rates from 14% to 41% varied by age, gender, city size, number of subjects and length of time for enrollment, and method of approach. Cognitively impaired subjects had higher refusal rates which affected prevalence estimates. At one study site, efforts to “convert” subjects who initially refused to participate in the survey were successful with 26% of those who were recontacted.

Objective: To estimate the incidence of dementia, including AD, among Canadians aged 65 and over. Methods: A 5-year cohort study of 10,263 seniors was undertaken, including community and institutional samples. The baseline study in 1991 identified 1,132 prevalent cases of dementia through screening and clinical examination. The remaining 9,131 cases formed the incidence study sample and were rescreened and selectively reexamined in 1996. Incident cases were diagnosed using established criteria. Incidence was estimated based on the 1991 population, and included data on those who died between the first and second phases of the study. Results: Of the nondemented cohort who remained alive in 1996, 5,432 people in the community (88.3%) and 210 (91.3%) in the institutional sample participated in the incidence study. Nine hundred sixty incident cases were identified; the overall age-standardized incidence rates were 21.8 (women) and 19.1 (men) per 1,000 nondemented. persons per year. This translates into 60,150 new cases of dementia per year in Canada. The logarithm of the rates rises linearly with age, but suggests a slight slowing of growth in incidence in the oldest age groups. Conclusions: Our incidence estimates lie toward the upper end of the range of incidence estimates found in other studies. Nonetheless, we calculate that several factors may have biased our estimates downward, suggesting that the incidence of dementia may be higher than many studies have reported.

This paper describes patterns of caring for people aged 65 or over with dementia in Canada, and the relationship this has with the well-being of caregivers. Data were drawn from a representative sample of elderly people, selected from the community and from institutions in the ten provinces of Canada as part of the Canadian Study of Health and Aging (CSHA). Interviews were held with the caregivers of people diagnosed with dementia, and with a comparison group of caregivers for non-demented persons. About half of all people with dementia in Canada are living in the community, and our results show that over 98 per cent of them have a caregiver. The caregivers in 94 per cent of these cases are unpaid family members, relatives or friends: the spouse in 37 per cent of cases and a daughter in 29 per cent. Caregivers rarely use community support services. Among those caring for someone in the community, those caring for a person with dementia are more likely to experience chronic health problems and depressive symptoms than are those caring for a non-demented elderly person. Those caring for a person in the community are much more likely to feel burdened than those whose loved one is in an institution, even though those who are institutionalized are more likely to suffer from severe dementia. These national figures support many of the findings reported from smaller, localized studies. The findings suggest that long-term care institutions are serving a role for Canada's seniors, particularly for the most demented, and that caregivers often provide care for loved ones even when suffering from chronic health conditions, depression, and burden themselves.

Objective: To estimate the prevalence of dementia and its subtypes by sex and age group for five regions of Canada.Design: Prevalence survey.Setting: Community and institutional settings in Canada, excluding those in the two territories, Indian reserves and military units.Participants: Representative sample of people aged 65 and over interviewed between February 1991 and May 1992. Those in the community (9008 subjects) were chosen randomly from medicare lists in nine provinces or from the Enumeration Composite Record in Ontario. People in institutions (1255) were randomly selected from residents in stratified random samples of institutions in each region.Interventions: Screening with the Modified Mini-Mental State (3MS) Examination to identify cognitive impairment. Clinical examination of all those in institutions, those in the community with a 3MS score of less than 78 and a sample of those in the community with a 3MS score of 78 or more to diagnose dementia. Dementia and Alzheimer's disease were defined according to established criteria.Main outcome measures: Prevalence of dementia of all types, by region, sex and age group, the estimated number of cases in the population by type of dementia and the age-standardized rate per 1000 population.Results: The prevalence estimates suggested that 252 600 (8.0%) of all Canadians aged 65 and over met the criteria for dementia (95% confidence interval [CI] 236 800 to 268 400). These were divided roughly equally between the community and institutional samples; the female:male ratio was 2:1. The age-standardized rate ranged from 2.4%, among those aged 65 to 74 years, to 34.5%; among those aged 85 and over. The corresponding figures for Alzheimer's disease were 5.1% overall (161 000 cases; 95% CI 148 100 to 173 900), ranging from 1.0% to 26.0%; for vascular dementia it was 1.5% overall, ranging from 0.6% to 4.8%. If the prevalence estimates remain constant, the number of Canadians with dementia will rise to 592 000 by 2021.Conclusions: These Canadian estimates df the prevalence of dementia fall toward the upper end of the ranges in other studies, whereas the estimates for Alzheimer's disease fall in the middle of the ranges. This may suggest an unusual balance between Alzheimer's and other forms of dementia in the Canadian population.

Objective: To study risk factors for Alzheimer's disease (AD) based on data from the Canadian Study of Health and Aging. Design: Population-based case-control study. Setting: Communities and institutions in 10 Canadian provinces. Participants: Two hundred fifty-eight cases clinically diagnosed with probable AD, with onset of symptoms within 3 years of diagnosis, and 535 controls, frequency matched on age group, study center, and residence in community or institution, clinically confirmed to be cognitively normal. Main outcome measure: Odds ratios (ORs) were calculated using unconditional logistic regression for previously hypothesized and potential risk factors for AD. Results: The OR for family history of dementia was significantly elevated (2.62; 95% confidence interval [CI], 1.53 to 4.51) and increased with the number of relatives with dementia. Those with less education were at higher risk of AD, with an OR of 4.00 (95% CI, 2.49 to 6.43) for those with 0 to 6 years, in comparison with those with 10 or more years. Head injury achieved borderline significance. A history of arthritis resulted in a low risk of AD (OR = 0.54; 95% CI, 0.36 to 0.81), as did a history of use of nonsteroidal anti-inflammatory drugs, Initial analyses showed an increased risk of AD for occupational exposure to glues as well as to pesticides and fertilizers; the increased risk was greater in those with less education. Conclusion: This study confirmed a number of previously reported risk factors for AD, but provided little support for others. A new finding was an increased risk for those with occupational exposure to glues as well as pesticides and fertilizers, but this needs further study.