The term dementia refers to a group of degenerative diseases that affect cognitive function and lead to loss of functional autonomy. Vascular dementia and Alzheimer’s disease (AD) are the most common forms of dementia. In this report, the term “Alzheimer’s disease and related disorders” will be used.
Alzheimer’s disease and related disorders generally start appearing from the age of 60 to 65 years of age and onwards. They affect individuals’ daily functioning by disrupting their memory, judgment, organization, orientation, language or control over their behaviour and emotions. These diseases place a staggering burden on individuals who are affected, their families and caregivers, as well as on professionals and the health system.
To date, most estimates of the prevalence and incidence of AD and related disorders in Canada are still based on the Canadian Study of Health and Aging (CSHA), a large population study conducted across Canada between 1991 and 2001. This study provided Canadian results on prevalence in 1994, and on incidence in 2000. Based on the findings of the CSHA and on studies from Manitoba, the Alzheimer Society of Canada projected the incidence of new cases of AD and other forms of dementia in Canada at 104,000 per year in 2008, and that this number would exceed 250,000 in 2038. However, some more recent international population studies appear to have found that the incidence of AD and other forms of dementia may be decreasing, which could, for example, be attributable to an improvement in the cerebrovascular health of seniors.
Consequently, it appears necessary to calculate new estimates of the prevalence and incidence of AD and related disorders. To this end, the Canadian Longitudinal Study on Aging, a population study, is underway in Canada (https://www.clsa-elcv.ca/). However, because of the burden of these diseases, it seems imperative that a surveillance system be developed to monitor Alzheimer’s disease and related disorders in Québec as they become manifest within the Québec health system. The Institut national de santé publique du Québec is developing this surveillance through the Québec Integrated Chronic Disease Surveillance System (QICDSS).
The main objective of this report is to demonstrate the feasibility of developing surveillance of AD and related disorders in Québec. Specifically, the study uses the results and definitions identified from the literature, and compares annual prevalence, incidence and mortality estimates of AD and related disorders among Québec seniors aged 65 and over, between April 2000 and March 2011, using three different algorithms or case definitions and based on QICDSS data.