Atrial fibrillation is a relatively common condition, and - because of the aging population - it is becoming more common. This rise is mirrored by elevated usage of the blood-thinning drug, warfarin. The drug has saved countless lives, but new research shows a hidden danger - an increased risk of dementia in atrial fibrillation patients.

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Links between warfarin and dementia are uncovered by new research.

Warfarin has been used to prevent potentially life-threatening blood clots for more than half a century; an estimated 20 million Americans are currently taking the drug.

Atrial fibrillation (AF) refers to an irregular, often abnormally fast, heartbeat. It can cause a range of symptoms, including shortness of breath, dizziness, and tiredness.

There are an estimated 2.7 million Americans living with AF.

According to the American Heart Association, AF increases the risk of strokefivefold. For this reason, warfarin's ability to prevent blood clots is a potential life-saver.

Because blood clots can seriously affect brain function, AF is known to enhance the risk of developing dementia. On the other hand, blood thinners used to ease AF symptoms increase the likelihood of brain bleeds that can, over time, have a negative impact on brain function.

Warfarin and dementia

Warfarin has been used for many years and is prescribed in large quantities across the industrialized world. New research, presented at the Heart Rhythm Society's 37th Annual Scientific Sessions, used data from more than 10,000 patients to investigate links between warfarin, dementia, and AF.

Each of the participants in the study was a long-term user of warfarin. Some used the drug for AF, others used it for different conditions including thromboembolism and valvular heart disease. None had a history of dementia.

After 7 years, the group was followed up. The team found that dementia was more prevalent in the AF group than the non-AF group, 5.8 percent compared with 1.6 percent, respectively.

The study was conducted by Dr. T. Jared Bunch and a team of researchers at Intermountain Medical Center Heart Institute in Salt Lake City, UT. They showed that individuals using warfarin for AF on a long-term basis had increased rates of vascular dementia and Alzheimer's when compared with warfarin users with conditions other than AF.

The trouble with warfarin

Warfarin is a notoriously challenging drug to administer at the correct levels. A tightrope has to be walked between the risks of clotting on one side and bleeding on the other. Each patient responds differently to warfarin, and multiple factors can impact the drug's effects. Additionally, its actions in the body take time to develop, so finding the right dosage can be a long process. These factors combined make warfarin levels difficult to manage.

Previous research demonstrated that worse warfarin management might increase the chances of developing dementia in AF patients. The current research backed up these earlier findings; the risk was indeed heightened in patients whose dosage was more difficult to manage. However, they also found that, independent of the quality of warfarin management, dementia levels still increased.

In short, the researchers showed that whether warfarin levels were too high, too low, or at the right dosage, the risk of dementia still increased.

"Our study results are the first to show that there are significant cognitive risk factors for patients treated with Warfarin over a long period of time regardless of the indication for anticoagulation."

T. Jared Bunch, MD

Future concerns surrounding warfarin

For a number of reasons, Dr. Bunch believes that these results are of great importance. Firstly, it is important to know about any risks associated with a medication, especially one that is used so commonly. He recommends that only people who absolutely need blood thinners should be prescribed them.

Secondly, the results suggest that other medications that can increase the chances of bleeding, like aspirin, should be avoided by individuals taking blood thinners, unless entirely necessary. Also, for those who are taking warfarin, but whose dosage levels are difficult to manage, switching to newer, more predictable drugs might be a safer solution.

Because of warfarin's widespread usage, the findings of any research into its associated risks are likely to spark debate.

Learn about how yoga might help ease atrial fibrillation symptoms.