Stroke survivors have an 80% increased risk of dementia compared to people who’ve never suffered a stroke, a new study finds.

About 19% of people who’d had a stroke developed dementia during an average six-year follow-up, compared with just 13% of those with no stroke, researchers reported Dec. 4 in the journal Neurology.

“Importantly, our research also found that the risk of dementia after stroke was double the risk of having a second stroke,” said researcher Dr. Raed Joundi, an assistant professor of medicine with McMaster University in Hamilton, Canada.

“While much research has been focused on reducing the risk of a second stroke, our findings make it clear that that more research also is needed on developing interventions to help prevent dementia after stroke,” Joundi added in a journal news release.

For the study, researchers looked at strokes caused by either a blockage of blood flow to the brain or by bleeding in the brain.

The team identified nearly 175,000 stroke survivors living in Ontario, and matched them to the same number of people who hadn’t had a stroke. The average age of study participants was 69.

They found there were about 3.3 cases of dementia per 100 person-years for stroke survivors, compared with 1.9 cases among people without stroke. Person-years represent the number of people in the study and the amount of time each person was tracked.

People with stroke had a 76% increased risk of dementia after taking into account other risk factors like age, gender, high blood pressure and diabetes, results show.

The risk also changed over time, and was highest immediately following a stroke, researchers found.

Stroke survivors had a 2.5 times increased risk of dementia within a year of their stroke, a 50% increased risk at five years and a 30% increased risk after 20 years, result showed.

“As the rates of dementia are rising globally, and more people are surviving stroke, understanding the how stroke contributes to dementia risk is of great importance,” Joundi said.