Anticoagulant Overtreatment May Raise the Risk of Dementia

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Research presented at the American Heart Association’s Scientific Sessions 2014 reveals that long-term overtreatment with the anti-clotting drug warfarin, combined with antiplatelet therapy with aspirin or clopidigrel (Plavix) to prevent stroke, may raise the risk of dementia for people who have atrial fibrillation.

Atrial fibrillation is a common heart rhythm abnormality and it raises the individual’s risk of stroke and all common forms of dementia, according to MedicalXpress, though the mechanisms behind this are unknown. According to Dr. T. Jared Bunch, lead author of the study and director of electrophysiology at the Intermountain Medical Center Heart Institute in Murray, Utah, “The dual drug regimen is often used to prevent strokes in people with coronary artery disease or peripheral vascular disease, but we have to consider that long-term exposure to anti-clotting drugs such as warfarin, if not well controlled, can significantly increase bleeding risk.” The combination drug therapy may result in “micro bleeds” in the brain whose effects accumulate over time, “raising the risk of dementia,” Bunch explained.

The researchers studied 1,031 atrial fibrillation patients with no previous history of stroke or dementia for up to 10 years when they were on the drug combination, according to MedicalXpress. After the researchers had adjusted for traditional stroke and bleeding risk factors, they found that patients who had abnormally slow blood clotting times (International Normalized Ratio (INR) measurement above 3) on 25 percent or more of their monitoring tests were more than twice as likely to be diagnosed with dementia than patients with slow clotting times on less than 10 percent of tests. Abnormally slow clotting times were considered an indicator of too much medication.

The researchers conclude that both small bleeds and clots are important factors in the development of dementia in atrial fibrillation patients, according to MedicalXpress. Bunch said, “Even at skilled centers, it’s very common to have INR outside the ideal range up to 40 percent of the time, and over the years there may be an accumulative negative impact on cognitive ability.”

Because most of the patients in the study were Caucasian, the researchers are uncertain how their results would apply to other ethnic groups.