Many aging Americans have the heart arrhythmia known as atrial fibrillation (AFib), which research suggests could raise their risk for dementia.

In a Korean study, researchers noted that the link between AFib and dementia was found even among people who hadn’t suffered a stroke. AFib is a known risk factor for a stroke.

“People who developed atrial fibrillation had a 50 percent increased risk of developing dementia compared to those who did not develop the condition,” said study leader Boyoung Joung, professor of cardiology and internal medicine at Yonsei University College of Medicine in Seoul, South Korea. “This means that an extra 1.4 people per 100 of the population would develop dementia if they were diagnosed with atrial fibrillation. The risk occurred in people younger and older than 70,”

Joung explained in a news release. Finally, Joung said, “We also found that atrial fibrillation increased the risk of Alzheimer’s disease by 30 percent, and more than doubled the risk of vascular dementia.”