Explainer · Brain & Mental Health
Newer blood thinners went with slower memory decline in 7,308 Swedes with Alzheimer's
People with dementia are often left off anticoagulants for fear of bleeding. In Swedish registry data, those on newer blood thinners declined more slowly on memory tests and had fewer strokes.
- An observational study of 7,308 Swedes newly diagnosed with Alzheimer's disease who already had atrial fibrillation.
- Groups compared: no anticoagulant, warfarin, or a newer oral anticoagulant.
- The newer drugs went with memory test scores falling about 0.2 points a year more slowly than with no treatment.
- They also went with 19% lower death rates, 34% fewer strokes or clots, and no rise in major bleeding.
- People prescribed anticoagulants are usually healthier, so this cannot prove the drugs caused the difference.
Atrial fibrillation and Alzheimer’s disease often turn up in the same person, and they pull treatment in opposite directions. The irregular heartbeat calls for a blood thinner to prevent stroke; the dementia raises worries about falls, bleeding and whether pills will be taken as prescribed. Many patients end up on nothing.
A Swedish registry study in the European Heart Journal followed 7,308 people with both conditions. Those taking newer oral anticoagulants lost ground on memory tests more slowly, had fewer strokes and did not bleed more than those on no treatment.
What blood thinners do and why the choice is hard
MedlinePlus explains that blood thinners are medicines that prevent blood clots and that anticoagulants, one of the two main types, keep clots from forming or growing larger. In atrial fibrillation, that is what stops a clot in the heart traveling to the brain.
The trade-off is bleeding. MedlinePlus notes that the most common side effect is bleeding, which is the reason many people with dementia are left untreated. The authors frame the gap directly: use of NOACs is associated with reduced dementia risk in patients with atrial fibrillation (AF), but their impact on cognitive function in people who already have Alzheimer’s was unclear.
How the Swedish blood thinner study worked
The researchers used the national dementia registry to find people diagnosed with Alzheimer’s between 2007 and 2020 who already had atrial fibrillation, then looked at what they were taking. Among 7308 eligible individuals, 3,341 were on no anticoagulant, 2,277 on warfarin and 1,690 on a newer oral anticoagulant.
Because the groups differed at the outset, the team used a statistical weighting method to make them more comparable. Cognition was tracked with the Mini-Mental State Examination, a 30-point test, and the researchers also counted deaths, strokes, major bleeds and fractures.
What happened to memory scores and strokes
The cognitive difference was small and steady. NOAC users exhibited significantly slower cognitive decline compared to non-users, by 0.23 points a year on the 30-point test, and by 0.21 points a year compared with warfarin users.
The clinical outcomes pointed the same way. Compared with no anticoagulant, the newer drugs went with about 19% lower death rates, 34% fewer strokes or clots blocking an artery, and 21% fewer fractures, without an increased rate of major bleeding. Warfarin also reduced deaths and strokes, but with more major bleeding.
Why the anticoagulant choice matters in dementia
The practical question in clinic is whether a person with Alzheimer’s and atrial fibrillation should be anticoagulated at all, and if so, with what. This study suggests the newer drugs were not paid for with extra bleeding in this group, which is the main fear behind leaving people untreated.
The slower memory decline is the eye-catching part, but it is also the softest. A fifth of a point a year on a 30-point scale is not something a family would notice. It is more useful as a reason not to assume that treating the heart harms the brain.
What a blood thinner registry study cannot prove
Doctors choose who gets anticoagulants, and they tend to choose people who are steadier on their feet, less frail and better supported at home. Weighting can balance recorded factors such as age, other illnesses and medicines, but not the judgment that led to the prescription.
Memory test scores come from routine clinic visits, so people who stayed well enough to attend are over-represented. The study covers one country’s practice over a period when the newer drugs were replacing warfarin, and it cannot say which specific anticoagulant is best or how the findings apply to other dementias.
What this changes for families weighing blood thinners
For a family facing this decision, the message is that stopping or withholding an anticoagulant is not automatically the safer path. Stroke risk does not fall because someone has dementia.
The decision belongs with the treating doctor and should be revisited as the illness changes, taking in falls, bleeding history, kidney function and how reliably medicines can be taken. This study adds reassurance to that conversation rather than a rule.
People also ask
What did the study find?
Users of newer oral anticoagulants declined more slowly on the Mini-Mental State Examination than non-users (0.23 points per year, 95% CI 0.11 to 0.36) and than warfarin users (0.21 points per year). Compared with no anticoagulant, they had lower mortality (hazard ratio 0.81), fewer ischemic strokes or systemic emboli (0.66) and fewer fractures (0.79), with no increase in major bleeding (1.05).
What is atrial fibrillation?
An irregular, often fast heart rhythm. Blood can pool and form clots that travel to the brain, which is why it raises stroke risk and why anticoagulants are prescribed.
What are non-vitamin K oral anticoagulants?
A newer group of blood thinners, such as apixaban, rivaroxaban, edoxaban and dabigatran, which do not require the regular blood tests and dietary care that warfarin does.
How big is a 0.2-point difference on a memory test?
Small. The Mini-Mental State Examination runs to 30 points and people with Alzheimer's typically lose a few points a year, so this is a slowing of decline rather than an improvement.
Why would a blood thinner affect memory?
One idea is that preventing small, silent clots protects brain tissue over time. The study did not test mechanisms, and healthier patients are also more likely to be prescribed these drugs.
Should someone with dementia take an anticoagulant?
That is a decision for the treating doctor, weighing stroke risk against bleeding risk, falls and the ability to take medicines reliably. This is general information rather than medical advice.