Anti-coagulants may reduce risk of stroke and dementia in AF patients, study suggests

Results from a new register-based study performed by researchers at Karolinska Institutet have suggested that blood-thinning drugs not only reduce the risk of stroke in patients with atrial fibrillation (AF) but also significantly reduces the risk of dementia in these patients.

AF is a common disorder that is known to be associated with an increased risk of stroke and dementia. Blood-thinning drugs are used to treat these patients as they are known to reduce the likelihood of stroke but until now there has been no clear evidence of whether these drugs could also prevent dementia in AF patients.

Researchers from the Karolinska Institutet’s Department of Clinical Sciences, Danderyd Hospital, evaluated data from Swedish registries to see if there was a link between oral anticoagulant treatment and dementia in patients with AF. From the registries, they identified 26,210 AF patients that were diagnosed with dementia between 2006 and 2014. Of these patients, less than half were taking blood-thinning drugs to prevent blood clots when they first joined the study and they were found to have a 29% lower risk of developing dementia than patients who were not on any treatment at the start of the study.

Continuation of treatment for these patients gave rise to a 48% reduction in the risk of developing dementia. Additionally, the researchers found that the protective effect of the treatment was greater the sooner the treatment was started and there was no difference between the type of blood thinning drug (warfarin versus newer oral anticoagulants).

“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 Professor Mårten Rosenqvist, the study’s co-lead.

“Patients on oral anticoagulation for stroke prevention often stop taking the drugs after a few years,” added associate professor Leif Friberg, also co-lead of the study. “Doctors should explain to their patients how these drugs work and why they should use them. No brain can withstand a constant bombardment of microscopic clots in the long run.”

Speaking to The Guardian about these results Prof Jeremy Pearson, associate medical director at the British Heart Foundation, stated: “Strokes caused by a clot blocking the blood vessels in the brain are a major cause of dementia, and atrial fibrillation is an important risk factor as it increases the chances of these clots forming.

“By treating AF patients with blood-thinning drugs, you reduce the risk of both stroke and dementia.”

Dr Carol Routledge, head of science at Alzheimer’s Research UK, continued: “The findings highlight a need to investigate this link further, but the nature of the study prevents us from firmly concluding that anticoagulants reduce the risk of dementia.

“It will be important to see the results of other ongoing studies in this area, as well as teasing apart the exact relationship between anticoagulants and the risk of different types of dementia.”

The study has been published in the European Heart Journal.