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Depression in elderly Canadians is an important but often unrecognized public health problem. Numerous studies have examined depression in the general community, but studies of depression in the elderly have generally been small and limited. The Canadian Study of Health and Aging (CSHA) includes a large and national representation of both the cognitively intact and the cognitively impaired elderly. The current analyses of 2,341 participants from the CSHA who completed a clinical rating scale for depression have two objectives: 1) to determine the prevalence of minor and major depression and 2) to examine the importance of several risk factors. The prevalences of major and minor depression were 2.6 percent and 4.0 percent, respectively, and were higher for females, specifically those in institutions, those who reported that their health problems limited activities, and those with chronic health conditions. Women were more likely to exhibit depression (OR = 3.5; 95% CI: 1.4-8.8) than men, and those with dementia more likely to exhibit depression than those without (OR = 2.4; 95% CI: 0.9-3.1). Depression is a significant mental health problem among elderly Canadians, particularly among women and those with physical limitations. More attention should be paid to the detection and treatment of depression in the elderly, particularly among those most at risk.

The detection of mild cognitive impairment and dementia in high-functioning older adults can be difficult. It has also been observed that high-functioning persons show a lower prevalence of dementia than low-functioning persons. Three alternative explanations for this observation have been proposed in the literature: brain reserve capacity (BRC), cognitive reserve, and ascertainment bias. With data from a prospective, population-based study of incident dementia, the Canadian Study of Health and Aging (CSHA), we classified participants as being high- (HF) or low-functioning (LF) in three ways: educational and occupational attainment, and estimated premorbid IQ. We observed that fewer HF older adults were diagnosed with dementia after five years, which is in accordance with both the BRC and cognitive reserve models. Contrary to expectations, no difference on rate of memory deterioration was observed between those HF and LF persons who exhibited mild cognitive impairment at CSHA-1. However, HF persons who subsequently were diagnosed with dementia (CSHA-2) showed more rapid decline on five of the six memory measures over time than did LF persons diagnosed with dementia at CSHA-2. When performance on measures of memory functioning at CSHA-1 was examined for highly educated older adults, significantly more of those with dementia at CSHA-2 (n = 59) had scores falling within or below the average range in comparison to normative standards than those who continued to show no cognitive impairment (n = 145). Our findings suggest that the lower incidence of dementia for HF persons may be primarily the result of ascertainment bias, not underlying differences in brain or cognitive reserve.

Context: The importance of early identification of dementia has prompted numerous investigations of mild cognitive impairment and the preclinical stages of progressive degenerative disorders. To date, there is limited information from large-scale studies regarding outcomes of persons specifically identified with cognitive impairment but no dementia (CIND)., Objectives: To investigate outcomes for persons with no cognitive impairment (NCI) or CIND, focusing on its etiologic subcategories, from the Canadian Study of Health and Aging (CSHA) and to examine the predictive validity of a set of core features thought to be early manifestations of subsequent dementia., Design: Five-year, longitudinal follow-up of all persons without dementia examined during the first phase of the CSHA in 1991., Setting: Community and institutional settings., Participants: Population-based sample of 883 persons with NCI and 801 persons with CIND at the first phase of the CSHA. At follow-up, 517 persons with NCI (59%) and 327 persons with CIND (41%) were alive and received clinical diagnoses., Main Outcome Measures: Mortality, institutionalization, and clinical diagnoses using the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition criteria for dementia., Results: Persons with CIND were more likely than those with NCI to die (49% vs 30%), to be admitted to facility care (29% vs 14%), or to receive diagnoses of dementia (47% vs 15%) at follow-up. Those subsequently diagnosed as having dementia were more likely to have had impaired memory, informant-reported change in memory, and functional impairment at baseline., Conclusions: Persons with CIND were more likely to have a negative outcome than persons with NCI during a 5-year interval. This was true across etiologic subcategories and suggests that the use of specific diagnostic criteria sets does not improve our identification of those who develop dementia compared with a broader, more inclusive approach. More factors contributed to the prediction of all forms of dementia than to AD, but the most accurate prediction was for those who remained dementia free.

Background: Dementia is a predictor of death and institutionalization. It is less clear if variations in cognition within the normal range predict adverse outcomes., Objective: To determine if variation at the high end of cognitive test scores predicts mortality or institutionalization, independent of the effect of potential confounders., Design: Secondary analysis of the Canadian Study of Health and Aging, a population-based longitudinal study with an initial data collection in 1991 and follow-up five years later., Setting: Community-dwelling seniors living in Canada., Participants: 9008 consenting seniors were sampled from representative population registries in Canada., Measures: Age, gender, marital status, the Mini-Mental State Examination, self-rated health, and activities of daily living., Outcomes: Death or institutionalization over the five years of follow-up., Results: Mini-Mental State Examination scores predicted mortality and institutionalization. The unadjusted odds ratio of mortality was 0.85 (95% confidence interval 0.84, 0.86) per point on the Mini-Mental State Examination, and the adjusted odds ratio was 0.95 (95% confidence interval 0.93, 0.97). The unadjusted odds ratio for institutionalization was 0.83 (95% confidence interval 0.82, 0.85), and the adjusted odds ratio was 0.91 (95% confidence interval 0.90, 0.94). This effect was present even in analyses restricted to those within the normal range of Time 1 Mini-Mental State Examination scores., Conclusions: Low normal cognitive test scores predict adverse outcomes. Clinicians should consider close clinical follow-up of those with low normal cognitive test scores. Further research is needed to target seniors for follow-up and possible intervention to decrease mortality and institutionalization risk.

The Canadian Study of Health and Aging collected data focusing on the epidemiology of dementia, using interviews and questionnaires, clinical and neuropsychological examinations, physical measurements and blood collection, and access to public records such as death certificates, from people 65 and over in community (N = 9,008) institutional settings (N = 1,255). The study produced 12 data sets, including community health interviews, clinical and neuropsychological assessments, risk factor questionnaires, and caregiver interviews. This report describes the data collection and processing procedures, summarizes the content of each data set, and outlines the information collected in sufficient detail to permit its suitability for secondary analyses to be scrutinized.

This article reviews the concept of mild cognitive impairment in groups of people whose cognitive impairment does not warrant a diagnosis of dementia (cognitive impairment, no dementia; CIND). Problems with the application of existing sets of criteria to the Canadian Study of Health and Aging (CSHA) data sets are addressed and a procedure for identifying a subgroup presumed "at risk" for developing dementia is presented. Application of an informant's report of changes in cognitive functioning and neuropsychologists' ratings of mild to severe deficits in any of eight cognitive domains results in approximately half of the CIND cases being identified as "at risk." The rationale for the collection of specific information related to CIND in CSHA-2 is provided. A minority of people identified with CIND at CSHA-2 showed only memory impairment, and most demonstrated cognitive loss over the preceding five-year interval. This article provides a conceptual basis for procedures to identify people with cognitive impairment most likely to decline to dementia.

Lack of social support is an important risk factor for disability, psychiatric illness, cognitive impairment, institutionalization, and mortality. Social networks are also important for the caregiving and emotional support that elderly people need to allow them to function well in the community. This article details the development and validation of an index of the instrumental support available to older community residents in the Canadian Study of Health and Aging (CSHA). Preliminary item review, internal consistency, and exploratory factor analysis were carried out on a random half of the sample. The second half of the sample was used for cross-validation; internal consistency, exploratory factor analysis, and item response theory analysis were carried out. The final scale had six items; alpha internal consistency was 0.76 and IRT reliability was 0.85. A one-factor solution was most easily interpretable. IRT analyses showed that the scale was homogeneous and that most items were highly discriminating. The instrumental support scale also had a high correlation with size of social network; it was related to marital status and gender, and predicted institutionalization between the two phases of the study.

The association between marital status and mortality is well known; marital status has also been related to morbidity. In this paper, we examine the importance of marital status in relation to the presence or absence of dementia and to institutional residence, using data from the Canadian Study of Health and Aging. Three groups are compared: married, single and previously married. We show that the age-standardized prevalence of dementia and the proportions of elderly Canadians living in institutions with and without dementia are highest among single people and are also high for those who were previously married. These associations hold true for both women and men, but the relation between marital status and institutionalization is much stronger for men. Possible explanations and implications for the future care of the elderly are discussed.

A method is described for choosing optimal cut-points in screening test with a continuous score in order to divide people into any number of disease categories. The cut-points are chosen to minimize the overall expected loss, given a matrix of losses incurred by misclassifications. It is shown that the optimal cut-points depend on the column differences of the loss matrix. The effect of changing the loss matrix is examined. For the error counting matrix, where misclassifications are given equal weight, it is shown that the relationship between the minimal loss cut-point and the receiver operating characteristic (ROC) curve for two disease categories extends to the general case. The results of a study in which elderly people were screened for cognitive impairment and dementia are used to illustrate the method.