The data

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The data are from the Cognition Module of the 2009 Canadian Community Health Survey (CCHS)—Healthy Aging.  The sampling frame consisted of people aged 45 or older living in private dwellings in the ten provinces.  Residents of the three territories, Indian reserves, Crown lands, institutions and some remote regions, and full-time members of the Canadian Forces were excluded.  Data collection took place from December 2008 through November 2009 using Computer-Assisted Personal Interviewing. 

The Cognition Module was administered in English or French only to non-proxy respondents.  This differed from the main component of the CCHS, for which proxy responses were accepted if the mental or physical health of selected participants prevented them from completing the interview (2.2% of the sample).  Respondents excluded from the Cognition Module because they required a proxy reporter were more likely to have Alzheimer's disease or dementia or to have suffered a stroke than were those who did not need a proxy reporter.¹⁹  Exclusion of such respondents means that the cognitive functioning categories were created from a higher-functioning sample.²⁰  As well, because residents of long-term health care institutions (7% of seniors)¹⁸ were excluded from the CCHS, the sample becomes less representative of the entire senior population at successively older ages.

Other reasons why respondents were excluded from the Cognition Module included interviews by telephone, completion of the survey in a language other than English or French (non-proxy), and refusal to perform the trials.

The overall response rate to the Cognition Module was 62.3% (N = 25,864), compared with 74.4% for the entire sample.  Separate sampling weights were created specifically for use with the cognitive outcome variables.

This study is based on 13,176 people aged 65 or older who did not report a diagnosis of Alzheimer's disease or dementia and who completed the Cognition Module, representing a weighted population of 4.3 million.  In this sample, 81.8% responded to the immediate recall, 68.1% to the delayed recall, 91.3% to semantic fluency (animal-naming), and 88.0% to the Mental Alteration Test.  Missing responses were excluded from prevalence estimates for each task.

Standard errors in modelling were computed using a bootstrapping technique.²¹

Household income quintiles were defined:  lowest, low-middle, middle, high-middle and highest.

The living arrangements of respondents were classified as:  living alone, living with a spouse/partner, or other.

The presence of chronic conditions was established by asking respondents if a health professional had diagnosed them as having conditions that had lasted, or were expected to last, at least six months. Respondents were read a list of conditions.  Chronic conditions were self-reported and were not verified by an external source.

Based on body mass index (BMI) calculated from self-reported height and weight, respondents were classified as:  obese (BMI 30 kg/m² or more), overweight (BMI 25 to less than 30 kg/m² ), normal weight (BMI 18.5 to less than 25 kg/m² ), or underweight (BMI less than 18.5 kg/m² ).

Respondents were identified as having had a single fall or recurrent falls (two or more) based on the questions, "In the past 12 months, did you have any falls?"  and "How many times have you fallen in the past 12 months?"

Questions about respondents' ability to perform instrumental and basic activities were based on the OARS Multidimensional Assessment Questionnaire.³⁰  For this analysis, answers were grouped to identify respondents with mild impairment versus moderate/severe/total impairment.

Respondents who received home care in the past 12 months were categorized as those who received formal care only, informal care only, or both.

Frequent social participation was defined as at least weekly participation in at least one of eight community-related activities that included other people.

Respondents were asked how often they lacked companionship, felt left out, or felt isolated.  For this analysis, those who answered "some of the time" or "often" versus "hardly ever" on each of the three questions were classified as lonely.

Self-perceived health was based on the question, "In general, would you say your health is: …" Those who responded good, very good or excellent (versus fair or poor) were defined as having "positive" self-perceived health.  A similar question was used for self-perceived mental health.