Atrial fibrillation patients treated long term with the blood-thinning drug Warfarin may be at greater risk for dementia, Alzheimer’s disease, and vascular dementia, according to a new study by researchers at the Intermountain Medical Center Heart Institute in Salt Lake City.
Atrial fibrillation is the most common type of arrhythmia, which is an abnormality in the rate or rhythm of the heartbeat. During an arrhythmia, the heart can beat too quickly, too slowly, or with an irregular rhythm. Incidence rates of atrial fibrillation are growing dramatically as the population gets older.
Dementia is a neurological disorder that impairs memory and other cognitive abilities, and it is now listed among the leading causes of ill health and death in developed countries.
Atrial fibrillation in itself can increase the risk of dementia because it can lead to the development of both large and small clots that can affect brain function. In contrast, blood-thinning drugs used to prevent all forms of clots and strokes can increase the risk of brain bleeds that can also negatively impact brain function over time.
Researchers enrolled a total of 10,537 patients with no history of dementia prior to the study. The participants were being treated with a blood thinner for atrial fibrillation as well as non-AF conditions such as valvular heart disease and thromboembolism on a long-term basis.
During a follow-up of approximately seven years, researchers found that all types of dementia increased in the atrial fibrillation group more than the non-AF group.
The risk of dementia increased in both groups, however, as the time in therapeutic range decreased or became more erratic. When Warfarin levels were consistently too high or too low, dementia rates increased regardless of the patients’ reasons for taking the drug.
The findings show that regardless of the adequacy of anticoagulation, atrial fibrillation patients consistently experienced higher rates of all forms of dementia. This finding indicates that the efficacy of therapy is strongly associated with dementia.
Of note, researchers found that patients younger than 70 years tended to be the most susceptible to the risk of dementia.
“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,” said lead author T. Jared Bunch, M.D., director of heart rhythm research at Intermountain Medical Center Heart Institute and medical director for heart rhythm services for the Intermountain Healthcare system.
“First, as physicians we have to understand that although we need to use anticoagulants for many reasons including to prevent stroke in AF patients, at that same time there are risks that need to be considered some of which we are only right now beginning to understand,” he said.
“In this regard, only those that absolutely need blood thinners should be placed on them long-term. Second, other medications like aspirin that may increase the blood thinners effect should be avoided unless there is a specific medical need. Finally, in people that are on Warfarin in which the levels are erratic or difficult to control, switching to newer agents that are more predictable may lower risk.”
In conclusion, the findings pave the way for the use of alternative treatment approaches for patients with AF and for those taking a blood thinner for other needs. With atrial fibrillation raising the risk of dementia — in addition to and independent of anticoagulation — choosing an appropriate treatment may be a way to reduce the risk for dementia.
The findings were presented at Heart Rhythm 2016, the Heart Rhythm Society’s 37th Annual Scientific Sessions in San Francisco.
Source: Intermountain Medical Center