Combination of Blood Thinners Linked to Higher Risk of Dementia, Researchers FindNov 18, 2014
Research suggests an increased risk of dementia among atrial fibrillation patients who took the anti-clotting drug warfarin in combination with anti-platelet drugs aspirin or clopidogrel (sold under the brand name Plavix). According to Medical Xpress, the findings were presented at the American Heart Association’s Scientific Sessions 2014.
Patients with atrial fibrillation suffer from an abnormal heart rhythm that could increase the risk of stroke. All forms of common dementia are also linked to atrial fibrillation, although the mechanism is unknown.
"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," said T. Jared Bunch, M.D., who is the director of electrophysiology at the Intermountain Medical Center Heart Institute in Murray, Utah and lead researcher of the study. "This may result in micro bleeds in the brain that don't cause symptoms right away, but accumulate over time raising the risk of dementia."
The study analyzed data on 1,031 patients who did not have any history of stroke or dementia for up to 10 years while taking the drug combination. The researchers found that patients were twice as likely to be diagnosed with dementia if they had abnormally slow blood clotting times, measured as having an International Normalized Ration (INR) of greater than 3, on 25 percent or more of their monitoring tests compared to patients whose tests showed overtreatment less than 10 percent of the time. Abnormally slow clotting times is interpreted as a sign of being over-medicated.
These figures are higher than the findings of a previous study looking at warfarin alone. In past research, patients taking warfarin were shown to have an increased risk of dementia if their clotting times were too slow, which leads to a higher risk of bleeding, or too fast, leading to a higher risk of blood clots. Based on these findings, researchers suspected that dementia among atrial fibrillation patients is affected by small bleeds and clots.
"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," Bunch stated. "If your INRs are consistently too high, for stroke prevention your doctor may want to consider switching you to one of the newer anti-clotting drugs that is easier to regulate or a device placed into the heart that prevents clots from forming or exiting the area in the heart chamber where most clots develop in people with atrial fibrillation,"