Stroke can significantly increase the risk of developing dementia, and this risk is highest in the first year after a stroke and remains elevated over a 20-year period.

This is according to research that will be presented at this year’s International Stroke Conference of the American Stroke Association.

The research was done on databases of the University of Toronto in Canada, which included information on more than 15 million people. They identified more than 180,000 people who had had a recent stroke, either ischemic or intracerebral hemorrhage. They then compared the stroke survivors to two control groups, people in the general population who had not had a heart attack or stroke, and people who had had a heart attack and not a stroke.

It found that the risk of dementia was nearly three times higher in the first year after a stroke, then fell to a one-and-a-half-fold increased risk by five years, and remained elevated 20 years later. Dementia occurred in nearly 19% of stroke survivors during an average follow-up of five and a half years. In addition, the risk of dementia was 80% higher in stroke survivors compared to the general population, but also compared to a control group who had had a heart attack. Finally, the risk of dementia in people who had suffered an intracerebral hemorrhage was almost 150% higher than in the general population.