Millions of older adults have wondered whether a daily baby aspirin might protect their brain as well as their heart. Large trials have said no. But a new analysis from Australia suggests the answer may depend on your genes, though experts warn it’s far too early for anyone to start taking aspirin to prevent dementia.
Key Takeaways
- In a subgroup of older adults with a genetic tendency toward higher platelet counts, those taking low-dose aspirin were about 70% less likely to develop dementia than those taking a placebo. The study was published in Alzheimer’s & Dementia in October 2026.
- In absolute terms, the difference was small: 1% of aspirin users in this group developed dementia, compared with 3.3% on placebo.
- The same group had more than double the rate of major bleeding on aspirin: 4.4%, compared with 2.1% on placebo.
- Across all participants, aspirin did not lower dementia risk, confirming earlier results.
- The genetic test used in the study isn’t available to patients, and the researchers stress that no one should start aspirin for dementia prevention based on these findings.
What the study found
Researchers at Monash University in Melbourne analyzed genetic data from the ASPREE trial (Aspirin in Reducing Events in the Elderly). That major study randomly assigned healthy older adults in Australia and the U.S. to take 100 mg of aspirin or a placebo every day. More than 13,500 participants were included in this analysis.
Each participant was given a “polygenic score,” a measure that combines many small genetic variations, estimating their tendency to have a higher number of platelets. Platelets are tiny blood cells that help blood clot, and aspirin works partly by making them less sticky.
When the researchers compared people in the top 20% of genetic scores for platelet count:
- Dementia: 1% of those on aspirin developed dementia, compared with 3.3% of those on placebo. That’s roughly a 70% lower relative risk.
- Major bleeding: 4.4% of those on aspirin had a major bleed, compared with 2.1% on placebo.
Among participants as a whole, aspirin made no difference to dementia risk.
Why platelets might matter
Earlier research has linked dementia to overactive platelets that clump together, which may contribute to tiny blockages or inflammation in the brain’s small blood vessels. The genetic signal in this study didn’t overlap with known genetic risk factors for Alzheimer’s disease, which the researchers say points to platelet biology as a new avenue for dementia research.
The lead researcher said the findings suggest that genetic makeup could one day help guide which prevention strategies are right for which people, rather than a one-size-fits-all approach.
What the study can’t tell us
This finding comes from a subgroup within a larger trial, and results from subgroups are more likely to happen by chance. The researchers say the finding needs to be confirmed in other populations and then tested in a trial designed specifically for people with this genetic profile.
The increase in bleeding is a serious concern. The main ASPREE results, published in 2018, found that daily aspirin didn’t help healthy older adults live longer or stay free of disability, and it raised the risk of major bleeding, including bleeding in the brain and stomach.
What this means for you
- Don’t start aspirin to prevent dementia. The researchers themselves warn against it, and the bleeding risk is real.
- Talk to your doctor before starting or stopping daily aspirin. Current U.S. guidelines advise against starting aspirin to prevent a first heart attack or stroke in adults 60 and older, because the bleeding risks generally outweigh the benefits. But if you take aspirin because you’ve already had a heart attack, stroke or stent, don’t stop without medical advice.
- Focus on proven ways to protect your brain. Controlling blood pressure, staying physically active, not smoking, managing blood sugar and cholesterol, treating hearing loss, staying socially connected and getting good sleep are all linked to lower dementia risk.
This isn’t a substitute for medical advice. Talk to your doctor about what’s right for you.
Sources:
- Fransquet PD, McNeil JJ, Lacaze P, et al. Platelet count polygenic scores may modify the effect of aspirin in primary prevention of dementia. Alzheimer’s & Dementia, 2026. doi:10.1002/alz.71817
- Monash University via ScienceDaily: Low-dose aspirin linked to 70% lower dementia risk, but there’s a catch. October 25, 2026.
- McNeil JJ, et al. Effect of aspirin on disability-free survival in the healthy elderly. New England Journal of Medicine, 2018.
- U.S. Preventive Services Task Force. Aspirin use to prevent cardiovascular disease: recommendation statement. 2022.