Long-term treatment with the blood thinner warfarin has been connected to dementia in a study that examined over 10,000 patients with atrial fibrillation (AF) and compared data to those without AF.
The study was conducted by researchers from the Intermountain Medical Center Heart Institute in Salt Lake City and found that AF patients that were treated with warfarin long term had higher rates of dementia, Alzheimer's disease and vascular dementia when compared to a group of anticoagulated non-AF patients.
AF is the most common type of arrhythmia, which refers to a problem with the rate or rhythm of the heartbeat, causing it to beat too fast, too slow or at an irregular rate. As the population ages, incidence rates of AF continue to grow.
Dementia is a neurological disorder that disrupts both memory and other cognitive abilities, and the large and small clots caused by AF can increase the risk of dementia due to their effects on brain function. Furthermore, blood thinners such as warfarin can increase the risk of small and large brain bleeds, which can also have detrimental effects on brain function over time.
The new study examined a total of 10,537 patients with no history of dementia that were treated with a blood thinner for AF and non-AF conditions. During a seven-year follow-up, the data revealed that all types of dementia were increased in the AF group compared to the non-AF group.
The results also revealed that although dementia increased with time in both groups as time in therapeutic range decreased, when warfarin levels were either consistently too high or too low, dementia rates increased regardless of the group.
"Our study results are the first to show that there are significant cognitive risk factors for patients treated with warfarin over a long period of time regardless of the indication for anticoagulation," said T. Jared Bunch of the Intermountain Medical Center Heart Institute and lead author of the study.
"First, as physicians we have to understand that although we need to use anticoagulants for many reasons including to prevent stroke in AF patients, at that same time there are risks that need to be considered some of which we are only right now beginning to understand," he said.
"In this regard, only those that absolutely need blood thinners should be placed on them long-term," he continued. "Second, other medications like aspirin that may increase the blood thinners effect should be avoided unless there is a specific medical need. Finally, in people that are on warfarin in which the levels are erratic or difficult to control, switching to newer agents that are more predictable may lower risk."
The study, which has yet to be published, was presented Wednesday at the Heart Rhythm Society's annual meeting in San Francisco.