A nationwide Swedish study has found that a class of blood thinners known as NOACs may slow the loss of cognitive function in people who have both Alzheimer's disease and atrial fibrillation. The findings were published August 12 in the European Heart Journal.
The study looked at more than 7,300 individuals in Sweden who had been diagnosed with Alzheimer's disease and also had atrial fibrillation, an irregular heart rhythm, before their dementia diagnosis. According to Healthline, researchers drew on multiple linked national Swedish registries that contained detailed information on dementia diagnoses, cognitive test scores, hospital visits, prescription medications, and deaths.
NOACs, which stands for non-vitamin K antagonist oral anticoagulants, are a newer generation of blood thinners. Patients in the study were divided into three groups: those taking no blood thinner, those taking warfarin, an older and widely used anticoagulant, and those taking NOACs. Researchers then tracked changes in cognitive test scores for up to five years, along with health events including strokes, major bleeding, fractures, and death.
The primary tool used to measure cognitive function was the Mini-Mental State Examination, a standard test that assesses memory, attention, and related skills. The study found that patients taking NOACs experienced a slower decline in scores on that test compared to both warfarin users and those taking no blood thinner at all.
The connection between blood thinners and brain health in these patients relates to a specific risk that comes with having both conditions at once. People with Alzheimer's and AFib are prone to what researchers call silent strokes, small clotting events in the brain that can cause damage without obvious symptoms. Blood thinners work by reducing the formation of clots, which may in turn limit that kind of low-level brain injury.
Lead study co-author Maria Eriksdotter, a professor at the Department of Neurobiology, Care Sciences and Society at the Karolinska Institutet and senior consultant in geriatric medicine at Karolinska University Hospital in Stockholm, said the mechanism may go beyond just stroke prevention. "There are reasons to believe that the treatment could have a positive effect on cognition, for example by improving blood flow and reducing small-scale damage in the brain," she said in a news release.
Researchers used statistical methods to balance differences between the patient groups, accounting for factors like age, other health conditions, and additional medications. This was intended to reduce the chance that outside variables, rather than the blood thinners themselves, were driving the results.
The findings carry practical implications. Prescribing blood thinners to Alzheimer's patients has historically involved caution because of the added risk of falls and bleeding in an already vulnerable population. The study suggests that NOACs, which are generally considered safer and more predictable than warfarin, may offer a way to provide those patients with anticoagulant protection while also potentially supporting brain health. Experts cited in the report noted that NOACs are preferable to warfarin in most cases because their effects are more consistent and they require less frequent monitoring.
The research adds to a growing body of evidence that cardiovascular interventions can affect the course of cognitive diseases, and it points toward more targeted treatment options for a population that has limited options for slowing the progression of Alzheimer's.