PhotoResearchers studying the blood thinner Warfarin have linked the drug with higher rates of dementia and higher risk of kidney failure. But they note the risks mostly affect those using the drug to treat atrial fibrillation.

In the first phase of the study, researchers at the Intermountain Medical Center Heart Institute in Salt Lake City focused on atrial fibrillation patients who had been treated with Warfarin, a popular anticoagulant, for an extended period of time.

They found these patients tended to have higher rates of dementia, Alzheimer’s disease, and vascular dementia compared to patients receiving other treatment.

Type of arrhythmia

Atrial fibrillation is a type of arrhythmia, a condition in which the heart beats at an irregular rate or rhythm. This condition has become more common in recent years, primarily due to an aging population.

In their study, the scientists followed 10,000 patients with no history of dementia. They took Warfarin to treat atrial fibrillation and other conditions.

After seven years, the researchers found an increase in dementia in the group taking Warfarin for atrial fibrillation but not in the group of patients who took the drug to treat other types of conditions.

But both groups had one thing in common. The risk of dementia rose when levels of the drug fluctuated. When the levels of Warfarin in the bloodstream were too high or low, all patients in the study were more likely to suffer some form of dementia.

Other than that, researchers found patients with atrial fibrillation were the most likely users of Warfarin to develop dementia. Patients under age 70 appear to be more at risk.

Effect on kidneys

The second phase of the study looked at how Warfarin affects kidney function. In studying 2,753 patients with atrial fibrillation who were anticoagulated using Warfarin, the scientists found they were at a higher risk of developing kidney failure.

Again, the risk was linked to inconsistent levels of Warfarin in the body, not just from prescribed levels but also changes caused by Warfarin's interaction with food and other drugs. It's a delicate balance, the scientists say, because too much of the drug can lead to hemorrhaging and too little increases the risk of blood clots, leading to a stroke or heart attach.

“Patients who use Warfarin as part of their anticoagulation treatment for atrial fibrillation should have their anticoagulation levels closely monitored to ensure proper levels,” said Intermountain's Dr. Jared Bunch.

He also says people with moderate kidney disease and erratic levels of Warfarin, despite close monitoring and care, should consider other approaches, such as newer drugs that have more predictable blood effects.

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