Predicting who will develop dementia in a cohort of Canadian seniors

Objectives:We examined whether easily attainable variables were useful in p redicting who became demented over a five year period and determined the ra tes of incident dementia for different categories of mild cognitive impairm ent. Methods: This was a cohort study of subjects recruited nationally in a population-based survey of Canadians 65 years and older (the Canadian Stud y of Health and Aging). After standardized clinical assessments, a subset o f subjects (n=1782) was categorized as not demented at time one, Identical study methods allowed a reassessment of the cognitive status of surviving s ubjects (n=892) five years later. Results: Three baseline variables (Modifi ed Mini Mental State (3MS)score, subject's age, and an informant's report o f the presence of memory problems) were statistically significant predictor s of the development of a dementia. An equation incorporating these three v ariables had a sensitivity of 79% and a specificity of 56% for predicting d ementia among survivors at time two. An equation substituting the MMSE for the 3MS showed similar results. The various categories of mild cognitive im pairment examined showed Significantly different likelihoods for the subseq uent 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 o f age based normative data. Conclusion: In the absence of extensive laborat ory, radiologic or neuropsychological tests, simple variables that can be e asily determined in the course of a single clinical encounter were useful i n predicting subjects with a higher risk of developing dementia. Attempts t o use neuropsychological results to predict the development of dementia sho uld look for significant impairments on age-standardized tests.