By Steven Reinberg
The good news from this study: Blood thinners can reduce the odds for stroke and maybe delay or prevent dementia, researchers say.
"Our findings emphasize the need to improve the clinical management of patients with atrial fibrillation, which is very important since a considerable proportion of older people with atrial fibrillation are not using [anti-clotting] drugs," said study first author Mozhu Ding. She is with the Aging Research Center at the Karolinska Institute in Solna, Sweden.
For the study, Ding and her colleagues collected data on nearly 2,700 Swedes, average age 73.
Participants were examined at the start of the study and again after six years if they were younger than 78 or every three years for those older than that. None had dementia at the outset, and 9 percent had atrial fibrillation.
Over the study period, an additional 11 percent developed A-fib, and 15 percent developed dementia.
The researchers found that thinking and memory skills declined faster among those who had atrial fibrillation. They were 40 percent more likely to develop dementia than those without the heart condition.
However, those who took blood thinners because of the heart disorder had a 60 percent lower risk of developing dementia -- 11 percent taking anti-clot drugs developed dementia compared to 22 percent not taking them. No decreased risk was seen among those taking aspirin, the researchers found.
This study is observational, so it cannot prove that A-fib is a cause of dementia or that blood thinners prevent it. Still, the researchers believe additional efforts should be made to increase blood thinner use among older people with atrial fibrillation.
One limitation of the study is that Ding's group did not distinguish between different types of atrial fibrillation. Also, some A-fib cases may have been missed among those who didn't have symptoms.
One specialist said even tiny strokes that go unnoticed can be a gateway to dementia.
"Atrial fibrillation is associated with formation of clots that travel to the brain," said Dr. Sam Gandy, director of the Mount Sinai Center for Cognitive Health in New York City.
It's been thought that blood thinners effectively prevent this, he said.
"But with more refined neuropsychological exams and higher resolution scans we now see that while we are preventing major strokes, we apparently are not preventing formation of micro-clots that do more damage than previously realized," Gandy said. "This is being recognized and documented more and more, as in the current study."
The report was published online Oct. 10 in the journal Neurology.