Abstract
OBJECTIVES: There are more than 66,000 Ontario adults living with intellectual and developmental disabilities (IDD). While the risk of dementia is well established among those with Down Syndrome (DS), there is limited research in persons with IDD excluding DS (Non-DS IDD). This study aimed to compare the incidence and prevalence of dementia in Ontario adults with and without IDD over time and by demographic information. METHODS: Administrative data were used to calculate and compare the annual age- and sex-adjusted cumulative incidence and period prevalence of dementia from fiscal years 2011/12 to 2020/21 in three cohorts: (1) Non-DS IDD, (2) DS, and (3) No IDD. RESULTS: Compared to persons without IDD, cumulative incidence of dementia was on average 4.27 and 5.33 times higher in persons with Non-DS IDD and DS respectively and period prevalence of dementia was on average 4.87 and 5.93 times higher in persons with Non-DS IDD and DS respectively. CONCLUSIONS: Given the increased rates of dementia within the IDD population, it is imperative that early dementia screening take place, appropriate health and social services are implemented and more actions are taken to delay the onset of dementia, while considering the needs of this population.