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).
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.
here to download a copy of the Study Diagram (MS Word 32KB)
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
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 persons life.
The Clinical Examination: Diagnosing
The diagnosis of dementia was based on a combination of medical
assessments administered in the patients 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 Alzheimers
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 Alzheimers disease
of recent oneset, 129 with vascular dementia, and 535 cognitively
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 Alzheimers disease, who were
compared to 3,894 controls. For vascular dementia, 105 incident
cases were compared to 802 controls.
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:
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.
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