People with a particular kind of irregular heartbeat may experience faster decline in thinking and memory skills and are at greater risk of dementia, a study has found.
With atrial fibrillation, a form of arrhythmia, the heart's normal rhythm is out of sync. As a result, blood may pool in the heart, possibly forming clots that may go to the brain, causing a stroke.
However, the study published in the journal Neurology, also showed that people with atrial fibrillation who were taking anticoagulants, or blood thinners, to keep their blood from clotting were actually less likely to develop dementia.
"We know as people age, the chance of developing atrial fibrillation increases, as does the chance of developing dementia. Our research showed a clear link between the two and found that taking blood thinners may actually decrease the risk of dementia," said Qiu.
For the study, researchers looked at data on 2,685 participants with an average age of 73 who were followed for an average of six years as part of a larger study.
Participants were examined and interviewed at the start of the study and then once after six years for those younger than 78 and once every three years for those 78 and older. All participants were free of dementia at the start of the study, but 243 people, or 9 percent, had atrial fibrillation.
Through face-to-face interviews and medical examinations, researchers gathered lifestyle and medical data on participants at the start of the study and during each follow-up visit. All were screened for atrial fibrillation, for overall thinking and memory skills, as well as dementia.
Over the course of the study, an additional 279 people, or 11 per cent, developed atrial fibrillation, and 399, or 15 per cent, developed dementia.
Researchers found that those who had atrial fibrillation had a faster rate of decline in thinking and memory skills than those without the condition and were 40 per cent more likely to develop dementia.
Of the 2,163 people who did not have irregular heartbeat, 278 people developed dementia, or 10 per cent. Of the 522 people with irregular heartbeat, 121 developed dementia, or 23 per cent.
Researchers also found that people who took blood thinners for atrial fibrillation had a 60 per cent decreased risk of dementia. Of the 342 people who did not take blood thinners for the condition, 76 people developed dementia, or 22 per cent.
Of the 128 people taking blood thinners, 14 developed dementia, or 11 per cent. There was no decreased risk among people who took an antiplatelet treatment like aspirin.
Researchers said that could not distinguish subtypes of atrial fibrillation such as persistent or permanent. It is also possible that some cases of atrial fibrillation may have been missed among people who did not show any symptoms.