Some calculations on the prevalence of dementia in Canada

The epidemiology of dementia in Canada is not known. However, we report figures on the frequency of dementia in institutions in Ontario based upon the use of a multidimensional observation scale for the assessment of the elderly. These findings on institutionalized patients can be extrapolated to the whole elderly population, but the procedure is clearly too conservative by comparison with findings in other countries and in the light of the known occurrence of numbers of demented patients outside institutions. Ratios in different studies for the numbers of patients with dementia outside institutions and within institutions range from 1:1 to 6:1. Using a ratio of 2:1 and applying it to age specific population figures, a prevalence of dementia in Canada of 222,324 for those over 65 is obtained with a rate of 9.4% in that age group. When the figures projected in this way are compared with five epidemiological studies for the rate of dementia elsewhere, the Canadian figure which we have obtained ranks fourth out of six. This estimate provides potential figures on which to base the planning of services, provided that the inferential nature of the estimates is fully recognized.