Risk of dementia 3x higher after stroke at 1 year, elevated up to 20 years

Key takeaways:

• Rate of dementia was highest after acute stroke compared with the general population and patients with acute myocardial infarction.
• Dementia risk fell to 1.5-fold after 5 years.

For those with either acute ischemic stroke or intracerebral hemorrhage, risk of dementia was three times higher after the first year and remained elevated as many as 20 years after, a speaker said at the International Stroke Conference.

“People with acute stroke are at high risk of dementia,” Raed A. Joundi, MD, lead study author and assistant professor of medicine at McMaster University, and colleagues wrote. “Population-wide data on the risk and time-course of dementia after stroke are lacking.”

To address this data gap, Joundi and colleagues conducted a population-wide analysis of more than 15 million people in Ontario, Canada, between 2002 and 2022 via linked administrative databases. They identified 180,940 individuals who were 90-day survivors of an initial acute ischemic stroke or intracerebral hemorrhage (ICH) and compared them with healthy controls in the general population, as well as those with acute myocardial infarction (AMI), matched 1:1 based on age, sex, rural residence, neighborhood marginalization and vascular comorbidities.

Joundi and colleagues employed a validated definition that included hospitalization, physician claims and medications to calculate cause-specific hazard ratios overall and across all follow-up intervals to evaluate the rate of dementia per 100 person-years.

A total of 33,765 (18.7%) individuals developed dementia over a mean follow-up of 5.5 years.

Dementia risk was elevated approximately threefold in the first year after incident stroke, decreasing to 1.5-fold by 5 years and remaining elevated 20 years later, the researchers wrote.

The researchers also found the rate of dementia per 100 person-years was highest after acute stroke compared with the general population (3.40 vs. 1.88) as well as those with AMI (3.23 vs. 1.81), with overall risk of dementia higher in those with acute stroke compared with the general population (HR = 1.79, 95% CI: 1.76-1.82) and particularly after ICH (HR = 2.43, 2.31-2.57). Similar results were observed in comparison with AMI (HR = 1.77, 1.74-1.8).

“We found that the rate of post-stroke dementia was higher than the rate of recurrent stroke over the same time period,” Joundi said in the release. “Stroke injures the brain including areas critical for cognitive function, which can impact day-to-day functioning.”

Reference:

• Risk of dementia was nearly three times higher the first year after a stroke. https://newsroom.heart.org/news/risk-of-dementia-was-nearly-three-times-higher-the-first-year-after-a-stroke?preview=930e&preview_mode=True. Published Feb. 1, 2024. Accessed Feb. 6, 2024.