Warfarin Is Associated With High Rates Of Dementia

A new study reported its findings on May 5, 2016, that higher rates of dementia can be seen in patients treated with common blood thinner warfarin with atrial fibrillation compared to patients on the same drug without the common heart rhythm disorder.

The study, yet to be published, reported its results through the Intermountain Medical Center Heart Institute in Salt Lake City, where it was conducted. The research team presented the results at Heart Rhythm 2016 which was the 37th annual scientific session for the Heart Rhythm Society in San Francisco.

The study was conducted on a cohort of more than 10,000 patients who were being treated at the institute. The patients selected for the study were never diagnosed with dementia and had no indicators for the disease.

The patients were categorized according to different conditions such as atrial fibrillation, and non-AF conditions like thromboembolism and valvular heart disease. Other factors considered were hypertension, age, diabetes, renal failure, hyperlipidemia, smoking history, prior cerebral vascular accident or myocardial infarction, and heart failure. All patients were of 18 years or above.

All of the participants were then given the said blood thinner, warfarin, on a long term basis.

After a follow-up of seven years, the researchers found that the incidence of dementia was increased in the group with atrial fibrillation than for any other heart condition. With atrial fibrillation dementia was more prevalent at the rate of 5.8% and with 1.6% for the other conditions including valvular heart disease and thromboembolism.

However, in both instances of atrial fibrillation disorder and other non-AF disorders, the risk of dementia increased as the ‘therapeutic range decreased or became more erratic’.

A significant observation made in the study was that despite why patients were getting the blood thinner, if the dose levels were consistently too high or too low, the rates of patients developing dementia went up.

Another observation suggested that the efficacy of therapy was strongly associated with the incidence of dementia. Researchers observed that regardless of adequacy of anticoagulation, AF patients were consistently experiencing higher rates of dementia incidence.

Dementia is a neurological disorder which is currently one of the most leading causes of mortality and morbidity in developed countries. The disease can often impair memory and other cognitive abilities. Atrial fibrillation (AF), on the other hand, is the most common type of heart arrhythmia where the rate or rhythm of heart becomes irregular. During an episode of arrhythmia a heart can either beat too slowly, too fast or with an abnormal rhythm.

Atrial fibrillation is associated with increased risk of dementia as AF exposes the patient to both small and large clots which in turn affect brain function. Blood thinners used to help prevent formation of blood clots can cause further risk of small or large brain bleeds which can also have a negative impact on brain over time.

Scientists hope that this study which provides insights into associations between atrial fibrillation, dementia and anticoagulation can help with future treatments of patients with atrial fibrillation and people who are taking these drugs for other conditions.

The chief researcher Dr T Jared Bunch, Director of Heart Rhythm Research in Intermountain Medical Center Heart Institute and also the Medical Director of Heart Rhythm Services for the Intermountain Healthcare System, said, “The study is important in many ways.”

He explained that understanding that anticoagulants are important but still they come with risks that they are just beginning to understand, is important. He suggested that people should only be put on these drugs if they absolutely need them and no other avenues of treatment are available. He also made note that drugs which may help increase the effects of blood thinners like Aspirin should be avoided till a specific medical need requires their administration.

Dr Bunch also suggested that people for who are on warfarin in which levels can be erratic or difficult to control, switching to newer therapies and drugs which are more researched may be advisable.

Newer anticoagulant drugs that are currently available in the market include rivaroxaban (Xarelto), dabigatran (Pradaxa), and apixaban (Eliquis). Dr Bunch notes that these drugs do not have the same “swings” as warfarin.

Dr Gordon Tomaselli, Chief of Cardiology at John Hopkins University in Baltimore and a former President of American Heart Association, says that it is difficult to pinpoint warfarin management as the cause for dementia. However, it is plausible that erratic warfarin levels and atrial fibrillation can contribute to development of dementia.

Dr Tomaselli was not a part of the research team involved in the trial.

Previously another study has found that the quality of anticoagulation management among AF patients without dementia can be associated with the incidence of dementia in the said patients. The study hypothesized that a chronic cerebral injury can be the mechanism that underlies this particular association. The current study confirms these findings.

The study did not report any funding, conflict of interests or ties with the companies developing the new anticoagulant drugs.

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