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Predicting Who Will Develop Dementia in a Cohort of Canadian Seniors

Published online by Cambridge University Press:  04 August 2016

David B. Hogan*
Affiliation:
Departments of Medicine and Clinical Neurosciences, University of Calgary, Calgary, AB, Canada
Erika M. Ebly
Affiliation:
Departments of Medicine and Clinical Neurosciences, University of Calgary, Calgary, AB, Canada
*
Health Sciences Centre, University of Calgary, 3330 Hospital Dr., NW, Calgary Alberta T2N 4N1
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Abstract:

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Objectives:

We examined whether easily attainable variables were useful in predicting who became demented over a five year period and determined the rates of incident dementia for different categories of mild cognitive impairment.

Methods:

This was a cohort study of subjects recruited nationally in a population-based survey of Canadians 65 years and older (the Canadian Study of Health and Aging). After standardized clinical assessments, a subset of subjects (n=1782) was categorized as not demented at time one. Identical study methods allowed a reassessment of the cognitive status of surviving subjects (n=892) five years later.

Results:

Three baseline variables (Modified Mini Mental State (3MS) score, subject's age, and an informant's report of the presence of memory problems) were statistically significant predictors of the development of a dementia. An equation incorporating these three variables had a sensitivity of 79% and a specificity of 56% for predicting dementia among survivors at time two. An equation substituting the MMSE for the 3MS showed similar results. The various categories of mild cognitive impairment examined showed significantly different likelihoods for the subsequent development of a dementia. Some categories with a higher dementia risk were characterized by inclusion criteria requiring neuropsychological test scores that were greater than one standard deviation (SD) below the mean of age based normative data.

Conclusion:

In the absence of extensive laboratory, radiologic or neuropsychological tests, simple variables that can be easily determined in the course of a single clinical encounter were useful in predicting subjects with a higher risk of developing dementia. Attempts to use neuropsychological results to predict the development of dementia should look for significant impairments on age-standardized tests.

Résumé:

RÉSUMÉ:Objectifs:

Nous avons évalué si des variables facilement accessibles peuvent être utiles pour prédire qui deviendra dément dans les cinq prochaines années et nous avons déterminé l'incidence de la démence pour différentes catégories de déficits cognitifs légers.

Méthodes:

Il s'agit d'une étude de cohorte portant sur des sujets âgés de 65 ans et plus, recrutés à travers le Canada dans le cadre d'une étude de population (l'étude Canadienne sur la santé et le vieillissement). Suite à une évaluation clinique standardisée, un sous-groupe de sujets (n=1782) ont été classifiés comme déments au temps 1. Des méthodes d'étude identiques ont permis une réévaluation du statut cognitif des sujets survivants (n=892) cinq ans plus tard.

Résultats:

Trois variables de l'évaluation initiale (le score du mini mental modifié, l'âge du sujet et les troubles de mémoire rapportés par un informateur) étaient des prédicteurs significatifs du développement d'une démence. Une équation incorporant ces trois variables avait une sensibilité de 79% et une spécificité de 56% pour prédire la démence parmi les survivants au temps 2. Les différentes catégories de déficits cognitifs légers examinés ont montré des probabilités significativement différentes pour le développement subséquent d'une démence. Certains sous-groupes comportaient un risque plus élevé de démence notamment ceux dont les scores des tests neuropsychologiques étaient de plus d'une déviation standard sous la moyenne normative pour l'âge.

Conclusion:

En l'absence d'épreuves biologiques, radiologiques ou neuropsychologiques poussées, des variables simples qui peuvent être déterminées au cours d'une seule entrevue clinique ont été utiles pour prédire quels sujets avaient un risque plus élevé de développer une démence. Si des tests neuropsychologiques sont utilisés pour prédire le développement d'une démence on devrait rechercher des déficits significatifs au moyen d'épreuves standardisées pour l'âge.

Type
Original Article
Copyright
Copyright © The Canadian Journal of Neurological 2000

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