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Canadian Study of Health and Aging
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Design

Strategic and methodological considerations dictated a multicentre study with an overall sample of 10,250 people aged 65 or over. For reasons of regional equity, equal sized samples were drawn from the five geographic regions of Canada (British Columbia, the Prairie provinces, Ontario, Quebec, and the Atlantic region); the field work was implemented by 18 study centres (see map).

Study Centres

In each of the 18 study centres, a team was led by a principal investigator and typically included a coordinator, one or more physicians, a neuropsychologist, a nurse, a psychometrist, and a team of interviewers.

Phases of the Study:

The field work was undertaken in three main phases: the CSHA-1 field study in 1991-92, the CSHA-2 follow-up five years later in 1996-97, and CSHA-3 in 2001-2. In 1993-94 a small “Maintaining Contact Study” was undertaken by telephone, to update our address records, to announce that we would send participants an outline of the study results, and to mention the CSHA-2 follow-up. At the same time we asked brief questions on current health, and recorded information on those who had died.

With minor modifications, the same approach was used at CSHA-1, 2 and 3; the general procedures are illustrated in the document below.

People living in long-term care institutions proceeded directly to a clinical examination. Participants living in the community were first interviewed in their homes to record general health information and to screen for possible dementia.

Downloads

Click here to download a copy of the Study Diagram (MS Word 32KB)
Click here to download a copy of the Study Diagram (MS Word 32KB)

Community Interview:

This interview covered general health, disability, social circumstances, and the presence of chronic health problems. It also included a screening test for cognitive impairment, the Modified Mini-Mental State examination (3MS). Those who screened positive, plus a random sample of people who screened negative, were asked to attend a clinical assessment. In addition, at CSHA-2 and 3, all who had previously had a clinical examination were examined again.

For study subjects who had died before one of the follow-up studies, we interviewed a relative to collect information on cognitive and physical health during the last months of the person’s life.

The Clinical Examination: Diagnosing Dementia:

The diagnosis of dementia was based on a combination of medical and neuropsychological assessments administered in the patient’s home or at a clinic. After the physician and neuropsychologist had independently made preliminary diagnoses, they met with the nurse to reach a consensus diagnosis. This classified people as demented, cognitively impaired but not demented (“CIND”), or as cognitively normal. These diagnoses formed the basis for estimating the prevalence and incidence of dementia, and served as the case definition for the risk factor studies.

At the follow-up studies, we used the same diagnostic criteria for comparability with previous diagnoses, but then cases were re-diagnosed according to new criteria (such as the DSM-IV) that had been developed since the study began.

Risk Factor Study:

In a case-control design at CSHA-1, we compared risk factor information between cases diagnosed with Alzheimer’s disease or with vascular dementia, and cognitively normal controls. The risk factor questionnaire covered past medical history, family history, health behaviours, exposures to a range of substances. In addition, we drrew blood samples and undertook genetic analyses. Because the memory problems of dementia prevent patients from providing accurate information, the questionnaires at CSHA-1 were administered to an informant who knew the person well, typically the spouse. The case-control study included 258 cases with probable Alzheimer’s disease of recent oneset, 129 with vascular dementia, and 535 cognitively normal controls.

To establish a prospective risk factor study, all participants who were cognitively intact at CSHA-1 completed a risk factor questionnaire themselves. This involved 6,628 participants who screened cognitively normal and/or were diagnosed normal in the clinical examination. At CSHA-2, we undertook prospective risk factor analyses involving 194 recent-onset cases of Alzheimer’s disease, who were compared to 3,894 controls. For vascular dementia, 105 incident cases were compared to 802 controls.

Caregiving Studies:

We interviewed the caregivers of study participants at all three waves of the study.

The CSHA-1 caregiver study described the care provided to people with dementia in the various regions of Canada, both at home in the community, and in institutions. A comparison group included caregivers of a random sample of people who were not cognitively impaired. The study focussed on informal caregivers (spouses, family members or other relatives), but paid caregivers were include when no informal caregiver was available. The study also reviewed the health impact on family caregivers of looking after someone with dementia, at home or in an institution.

The CSHA-2 study re-assessed the same informal caregivers five years later, and analysed changes in their health according to changes in the health status of the person they were caring for.

The CSHA-3 caregiver study involved a comparison between informal caregivers of three groups of care-recipients: those who were diagnosed with dementia, others in the early stages of cognitive decline, and others who were physically frail but cognitively normal.

For fuller descriptions of the study methods, see:

Study Design:

Canadian Study of Health and Aging Working Group. Canadian Study of Health and Aging: study methods and prevalence of dementia. Canadian Medical Association Journal 1994;150:899-913

McDowell I, Hill G, Lindsay J. An overview of the Canadian Study of Health and Aging. International Psychogeriatrics 2001;13(Suppl 1):7-18

Risk Factor Studies:

Canadian Study of Health and Aging Working Group. The Canadian Study of Health and Aging: risk factors for Alzheimer's disease in Canada. Neurology 1994:44:2073-2080.

Lindsay J, Hébert R, Rockwood K. The Canadian Study of Health and Aging: risk factors for vascular dementia. Stroke 1997;28:526-530

Hébert R, Lindsay J, Verreault R, Rockwood K, Hill G, Dubois MF. Vascular dementia: incidence and risk factors in the Canadian Study of Health and Aging. Stroke 2000;31:1487-1493.

Caregiver:

Canadian Study of Health and Aging Working Group. Patterns of caring for people with dementia in Canada. Canadian Journal on Aging 1994;13:470-487

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