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Blood thinners may prevent dementia in atrial fibrillation patients–or they may not


3 Star


Blood Thinners May Prevent Dementia in Atrial Fibrillation Patients

Our Review Summary

Abnormal heart rhythms, called atrial fibrillation, are associated with increased risk of stroke and, in recent years, have also been linked to dementia. Blood thinners have typically been prescribed for atrial fibrillation patients at higher risk of stroke, while those at lower risk are often told to take aspirin.

This study recommends that nearly all atrial fibrillation patients take blood thinners, however, as the analysis found that their use is associated with lower rates of dementia.

The story reminds readers that the study conclusions are “preliminary,” an important cautionary note, but then leads with rather strong causal statements and allows the study author to vigorously recommend blood thinners for all atrial fibrillation patients. That recommendation may eventually be warranted, but only time and additional research will tell.


Why This Matters

Heightened risk of stroke in individuals diagnosed with irregular heart rhythms (3 to 6 million Americans, according to the CDC) is a serious issue, one that is compounded by growing evidence that these conditions are also linked to dementia. Strategies to interrupt that chain of events would be of great value.


Does the story adequately discuss the costs of the intervention?

Not Satisfactory

Although the lead author of the study makes a strong recommendation on behalf of prescribing blood thinners after an atrial fibrillation diagnosis, the text offers no information about what that ongoing treatment would cost.  While warfarin, the blood thinner identified in the story, remains relatively cheap, other drugs can cost hundreds of dollars per month.

Does the story adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The story renders benefits not in terms of reduction in risk but, rather, in terms of increased risk for signs of dementia. Specifically, it notes that delaying use of blood thinners in patients at low risk of stroke increases the risk of dementia by 30% and, in patients at high risk of stroke, by 136%. What it does not provide is any baseline numbers to permit a reader to judge “percentage of what?” Without that, it is difficult to decide if these risk increases are substantial or trivial. See more on the importance of including absolute risk numbers. 

Does the story adequately explain/quantify the harms of the intervention?

Not Satisfactory

Because blood thinners work by interfering with blood’s ability to clot, users are at some risk of dangerous heavy bleeding. This issue doesn’t make an appearance in the story.

Does the story seem to grasp the quality of the evidence?

Not Satisfactory

Readers will find just a few study details in this story, too few to enable them to make a reasonable judgment about study quality. The story does tell readers that the results have not yet been peer-reviewed for journal publication and, thus, must be regarded as “preliminary.” But such cautionary wording may be overwhelmed by the causal statements that dominate both the headline (Blood Thinners May Prevent Dementia in Atrial Fibrillation Patients) and the lead (“But a new study suggests these drugs may also help keep dementia at bay”). Until a randomized, controlled trial is conducted, we don’t know if this is the case. We only know if there are associations. See more on association vs causation in observational trials.

Does the story commit disease-mongering?


Stroke and dementia are a serious problem in developing countries with aging populations.

Does the story use independent sources and identify conflicts of interest?

Not Satisfactory

A second source appears to be independent of the study, although readers are not given enough information to determine that. It’s not clear who funded the study, and we think that should have been included.

Does the story compare the new approach with existing alternatives?


The story mentions use of aspirin and notes that “aspirin’s benefit in cutting the risk of dementia is limited.”

However, aspirin is not really recommended as an alternative to blood thinners (guidelines don’t recommend this anymore, so we were surprised to see it mentioned). But beyond this, there aren’t any real alternatives.

Does the story establish the availability of the treatment/test/product/procedure?


Warfarin is a common drug, as are a number of other blood thinners.

Does the story establish the true novelty of the approach?


The story makes it clear that what’s new here is how these researchers are recommending blood thinner therapy start immediately after an atrial fibrillation diagnosis, and for a wider group of patients.

Does the story appear to rely solely or largely on a news release?


The reporter clearly sought out at least one additional source, so there is evidence of enterprise here.

Total Score: 5 of 10 Satisfactory


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