Abstract 67: Risk and Time-Course of Post-Stroke Dementia: A Population-Wide Cohort Study, 2002-2022

Abstract

Background: People with acute stroke are at high risk of dementia. Population-wide data on the risk and time-course of dementia after stroke are lacking. Methods: We conducted a population-wide analysis of over 15 million people in Ontario, Canada between 2002-2022. Using linked administrative databases, we compared all 90-day survivors of first acute ischemic stroke or intracerebral hemorrhage (ICH) to controls in the general population and with acute myocardial infarction (AMI) by matching 1:1 on age, sex, rural residence, neighborhood marginalization, and vascular comorbidities, and excluded people with prior dementia. We evaluated the rate of dementia per 100 person-years using a validated definition which included hospitalization, physician claims, and medications, and calculated cause-specific hazard ratios overall and across follow-up time. Results: We identified 180,940 people with acute stroke, of which 33,765 (18.7%) developed dementia over mean follow-up of 5.5 years (max 20y). The rate of dementia per 100 person-years was highest after acute stroke compared to the general population (3.40 vs. 1.88) and compared to AMI (3.23 vs. 1.81). The overall risk of dementia was higher in those with acute stroke compared to the general population (HR 1.79, 95% CI 1.76-1.82; Figure 1A), and particularly after ICH (HR 2.43, 2.31-2.57). The results were similar when compared to AMI (HR 1.77, 1.74-1.80; Figure 1C). There was an almost 3-fold elevation of dementia risk in the first year after stroke, decreasing to 1.5-fold by 5 years and remaining elevated even 20 years after (Figure 1B/1D). Conclusion: In this large, population-wide study almost one fifth of people developed dementia after stroke, with an 80% higher risk of developing dementia compared to matched controls. The risk was highest early after stroke but remained elevated 20 years after, raising the urgency of developing interventions for dementia prevention in acute and chronic survivors of stroke.