Patients with an abnormal heart rhythm – known as atrial fibrillation – are at risk of experiencing a stroke due to the formation of small blood clots in the heart. In order to treat this condition, patients are prescribed blood thinner drugs, such as warfarin, which prevent the blood from clotting.
Now, researchers at the Intermountain Medical Center Heart Institute, have shown that atrial fibrillation patients taking warfarin are at an increased risk of developing dementia, compared to those taking the blood thinner for other medical conditions. As warfarin is the most commonly-prescribed anticoagulant drug, this research suggests that the drug itself is not the only factor contributing to the commonality of dementia among certain patient groups.
In their study, the researchers analyzed the medical records of over 6,000 patients who were chronically using warfarin for any indication. None of the patients had a history of dementia.
The researchers compared patients with atrial fibrillation with those who did not suffer from the condition, and found that the former patients were between two and three times more likely to develop dementia in their lives. In order to make this comparison, the study investigators controlled for multiple confounding factors which could increase the risk of dementia.
“Atrial fibrillation patients are at higher risk of developing all forms of dementia compared to patients without atrial fibrillation,” said Dr. Jared Bunch, lead author of the study and director of electrophysiology at the Intermountain Medical Center Heart Institute in Salt Lake City. “Warfarin is used to lower risk of stroke in patients with atrial fibrillation, but when the blood levels of the drug are erratic, it contributes to the dementia risk. This dementia risk is observed in people with and without atrial fibrillation that are exposed to long-term warfarin treatment.”
Previous research at Intermountain has shown that patients with atrial fibrillation have increased rates of dementia, including Alzheimer’s disease. Bunch and his team plan to conduct further studies to determine which treatments may be tied to dementia in these patients.
“Even when we consider the influence of warfarin on dementia risk, the presence of atrial fibrillation conveys additional risk of dementia,” said Bunch. “This suggests that the way we manage the abnormal heart rhythm, beyond just the practice of preventing blood clots through warfarin, may be a way we can further lower the risk of all forms of dementia, including Alzheimer’s disease, in patients with atrial fibrillation.”