Patients receiving treatment to correct or control atrial fibrillation, and end up being “overtreated” for a long period of time with anti-clotting medication warfarin, in combination with antiplatelet treatments aspirin or clopidigrel, may have an increased risk of developing dementia or Alzheimer’s disease according to a study presented at the American Heart Association’s Scientific Sessions 2014, and announced in a press release.
Atrial fibrillation, a heart rhythm deviation that can predispose a patient to stroke, is commonly treated with a combination of anti-clotting and antiplatelet medications. However, this research was able to demonstrate for the first time the correlation between atrial fibrillation and dementia.
“The dual drug regimen is often used to prevent strokes in people with coronary artery disease or peripheral vascular disease,” explained the lead author of the study and director of electrophysiology at the Intermountain Medical Center Heart Institute in Murray, Utah, T. Jared Bunch, M.D. “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.”
“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,” Bunch added. The study included 1,031 patients who had no previous history of either stroke nor dementia, and were being treated with the drug combination for up to 10 years.
The scientists adjusted their traditional stroke and bleeding risk factors, and observed that the patients with an International Normalized Ratio (INR) measurement above 3, which is an abnormally slow blood clotting level, in more than a quarter of the monitoring tests, had more than double the probability of developing dementia, when compared with other than patients whose tests revealed overtreatment in no less than 10 percent of the time.
“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 said. “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.”
The researchers recommend that patients currently on a combination of warfarin and an antiplatelet drug, such as aspirin or clopidgrel, consult their physicians about needing to take both. In addition, the authors noted that the increased risk is higher than they had observed when warfarin alone was analyzed in a previous research, as well as that the research was conducted mostly on Caucasian individuals, which reduces the certainties about its application to other ethnic groups.
In addition to Bunch, co-authors of the study are Heidi T. May, Ph.D.; Tami L. Bair, R.N.; Victoria Jacobs, N.P.; Brian G. Crandall, M.D.; J. Peter Weiss, M.D.; Jeffrey S. Osborn, M.D.; Charles Mallendar, M.D.; John D. Day, M.D.; Jeffrey L. Anderson, M.D.; Jeffrey L. Olson, M.D.; Katie Johanning; Yenh Long, Pharm.D.; Scott M. Stevens, M.D.; and Scott C. Woller, M.D.