Betsy Kristjansson

Community screening for dementia: The Mini Mental State Exam (MMSE) and modified Mini-Mental State Exam (3MS) compared☆

The objectives of this study were to assess whether Tengs modification of the Mini-Mental State Examination (MMSE) improves its performance as a screening test for cognitive impairment and dementia, and to replicate this comparison in French and English language groups, and for differing assumptions concerning the relative importance of false negative and false positive errors. Screening interviews were conducted with representative samples of people aged 65 or over, set in 36 communities in 10 Canadian provinces. There were 8900 community participants in the Canadian Study of Health and Aging, of whom 1600 also underwent an extensive clinical and neuropsychological examination. Sensitivity, specificity and areas under the receiver operating characteristic (ROC) curve for the original MMSE and modified version (the 3MS) were the main outcome measures. Results are reported for French and English versions of the tests. The results indicate the alpha internal consistency for the 3MS was 0.87, compared to 0.78 for the MMSE. The area under the ROC curve in identifying dementia was 0.93 for the 3MS and 0.89 for the MMSE (p < 0.001). There was less difference between the two tests in identifying all levels of cognitive impairment (AUC 0.80 versus 0.77, p < 0.01). The superiority of the 3MS appears more due to its extended scoring system than to its additional questions. The validity of the MMSE was comparable in English and French samples; results for the 3MS were inconsistent between the two samples, suggesting possible translation problems. In conclusion, the 3MS was superior to the MMSE, justifying the slightly greater burden for its administration and scoring. Neither test worked well in identifying lower levels of cognitive impairment.

Cognitive decline in high-functioning older adults: reserve or ascertainment bias?

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.

On the Classification of Population Health Measurements

Summary measures of population health, such as health-adjusted life expectancy, are increasingly being used to monitor the health status of regions and to evaluate public health interventions. Such measures are based on aggregated indicators of individual health and summarize health in a population. They describe population health status but have limitations in analytic studies of population health. We propose a broader framework for population health measurement. This classifies indicators according to their application (descriptive, prognostic, or explanatory), according to the conception of population (as an aggregate or a dynamic entity), and according to the underlying model of health. This approach extends the measurement repertoire to include indicators of the health of a population.

Development and validation of an indicator of support for community-residing older Canadians.

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.

Optimal cut-points when screening for more than one disease state: An example from the canadian study of health and aging☆

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.

Data collected in the Canadian Study of Health and Aging.

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.

Community level interventions to improve food security in developed countries

This is the protocol for a review and there is no abstract. The objectives are as follows: To systematically review the effects of community level interventions in improving food security in developed countries, both across whole communities and for disadvantaged or at-risk individuals or groups within a community. We also aim to identify features of community food security interventions that enable or impede the effective implementation of these interventions.