Oral anticoagulants (OACs) such as warfarin (Coumadin) are associated with a significant reduction in the risk of dementia among patients with atrial fibrillation (AF), according to a new study.
In the study, published October 25 online in European Heart Journal, researchers at the Karolinska Institutet’s Department of Clinical Sciences, Danderyd Hospital, in Sweden, identified patients in Sweden who were diagnosed with atrial fibrillation between 2006 and 2014.
Using data from the Swedish Patient Register and the Dispensed Drug Register (which covers all dispensed prescriptions in Sweden since July 2005), the researchers found that 22,610 of 444,106 patients with atrial fibrillation were diagnosed with dementia during the study period.
Less than half of the patients were taking blood-thinning drugs when they first joined the study, but those who were taking OACs at the start had a 29% lower risk of developing dementia than those who were not taking the drugs. When the researchers reviewed the period of time that patients continued to take OAC drugs, they found a 48% reduction in the risk of dementia. They also found that the protective effect against dementia was greater the sooner OAC treatment was started.
OACs are believed to prevent formation of tiny free-circulating clots, or microparticles. “No brain can withstand a constant shower of microparticles year after year without coming to harm. We might need to rethink risk assessment of atrial fibrillation,” Leif Friberg, co-author of the study and Associate Professor in Cardiology at Karolinska Institutet, told Drug Topics
“Although we can’t prove a causal relationship, we believe that the results strongly suggest that blood-thinning drugs protect against dementia in AF patients”, said Mårten Rosenqvist, co-author of the study and a Professor at the Karolinska Institutet, in a statement.
While health-care professionals “are getting quite good” at initiating treatment on patients with newly diagnosed atrial fibrillation, 15% discontinue treatment within the first year, according to Friberg. During each subsequent year, another 10% drop out.
“Proper patient education where patients are made to understand their disease, why they take their drugs, and how these work will lead to safer and more efficient drug use,” Friberg said.
The researchers found no difference in reduction of the risk of dementia between warfarin and newer oral anticoagulants. At baseline, a majority of the patients (42.1%) were on warfarin, while 1.2% were on dabigatran (Pradaxa), 1% were taking apixaban (Eliquis), 0.8% were taking rivaroxaban (Xarelto), and 0.04% were taking phenproumoumon (Marcoumar).
While the association between AF and dementia is well-documented, it is not clear if AF-related dementia can be prevented by OACs treatment.