1% against 3.3%, and the bleeding figure nobody should skip
What happened
Researchers at Monash University in Australia have reported that low-dose aspirin was linked to a much lower risk of dementia — but only in one particular genetic group, and at a cost. The team used genetic data from more than 13,500 people who took part in the ASPREE trial. ASPREE stands for Aspirin in Reducing Events in the Elderly. It was a large randomised trial in which older adults were given either low-dose aspirin or a placebo, which is a dummy tablet. The researchers gave each participant a genetic score linked to platelet count. Platelets are the tiny cells that help blood clot. Aspirin works partly by making platelets less sticky. Then they compared aspirin takers with placebo takers inside each genetic band. In the top 20% of platelet-count genetic scores, 1% of those on aspirin developed dementia, against 3.3% of those on placebo. In relative terms, that is roughly a 70% lower risk. Here is the catch, and it belongs in the same breath as the headline. In that same genetic group, 4.4% of aspirin takers had major bleeding, against 2.1% on placebo. The bleeding risk roughly doubled. The findings were published in Alzheimer’s & Dementia, the journal of the Alzheimer’s Association. Monash set them out in a press release reported on 25 October 2026.
Why this matters
Earlier trials, including ASPREE itself, found no overall protective effect of aspirin against dementia. That was a disappointment, and it largely closed the question. This analysis suggests the overall answer may have hidden two different answers. If aspirin helps one group and does nothing for everyone else, then averaging everybody together produces a result of roughly nothing — which is exactly what previous trials found. That is a genuinely interesting idea, and it points somewhere specific. The signal did not involve the well-known Alzheimer’s risk genes. It involved platelet biology. That opens a research direction that was not obviously on the list. The reason this matters to ordinary readers, though, is different and more immediate. Aspirin is cheap, familiar and easy to buy. A headline containing “70% lower dementia risk” is exactly the sort of thing that sends people to the chemist. This study is not a reason to do that, and the researchers say so plainly.
What the evidence actually says
Four limits are worth holding on to. First, this is a subgroup analysis. The researchers divided trial participants by genetic score after the trial had finished and looked for patterns. That is a legitimate and useful thing to do, but it is weaker evidence than a trial designed from the start to answer this question. Subgroup findings quite often fail to repeat. Second, the absolute numbers are small. The difference was 1% against 3.3%. That is a real difference, but it means around two extra cases of dementia per hundred people over the course of the trial — not a transformation. Third, the harm is in the same place as the benefit. Major bleeding went from 2.1% to 4.4% in the same genetic group. That is about two extra people per hundred with a serious bleed. Set against about two fewer per hundred with dementia, this is a trade, not a free win. Fourth, nobody can currently find out which group they are in by asking. The platelet genetic score used here is a research tool, not a test your GP can order. Dr Peter Fransquet, a research fellow at Monash’s School of Public Health and Preventive Medicine and the lead author, said it himself: “People shouldn’t start taking aspirin to prevent dementia on the basis of this study without consulting with their doctor.” He also set out what would need to happen next: confirm the finding in other populations, then run a clinical trial designed specifically for people with this genetic profile. That is years of work, not weeks.
Qurexa perspective
We deliver prescriptions and help people keep on top of the medicines they have been prescribed, so we see the other side of stories like this one. Every few months a study makes a familiar tablet sound like a quiet miracle. Someone then adds it to a daily routine that already contains four or five other medicines, without telling anyone. Aspirin is a particularly common one, because it sits on an open shelf and costs very little. That is the risk here. Low-dose aspirin thins the blood. If you are already taking an anticoagulant, certain anti-inflammatory painkillers, or some antidepressants, adding aspirin can raise bleeding risk in a way that is easy to miss until something goes wrong. If you are wondering whether aspirin is right for you, your community pharmacist can look at everything you take together and tell you whether it is a sensible question to put to your GP. That conversation is free, takes a few minutes, and needs no appointment. It is one of the most underused services in the NHS. If you already take aspirin because a doctor told you to, keep taking it. This study is not a reason to stop.
What to know
In more than 13,500 ASPREE trial participants, those in the top 20% of a platelet-count genetic score showed 1% dementia on low-dose aspirin against 3.3% on placebo — roughly 70% lower in relative terms. In the same group, major bleeding rose from 2.1% to 4.4%. Earlier trials found no overall dementia benefit from aspirin. This analysis suggests the effect may be limited to one genetic group, and points towards platelet biology rather than the usual Alzheimer’s genes. The limits are important: it is a subgroup analysis, the absolute numbers are small, the benefit and the bleeding risk fall on the same people, and there is no test you can ask for to find out which group you are in. The lead author says nobody should start aspirin for dementia on the strength of this work without speaking to their doctor. If aspirin interests you, ask your pharmacist to check it against everything else you take before you ask your GP. If you are already prescribed it, carry on. Sources: Monash University, “Low-dose aspirin linked to 70% lower dementia risk, but there’s a catch”, ScienceDaily, 25 October 2026, https://www.sciencedaily.com/releases/2026/10/261024222026.htm; Fransquet PD, et al., “Platelet count polygenic scores may modify the effect of aspirin in primary prevention of dementia”, Alzheimer’s & Dementia, 2026, https://doi.org/10.1002/alz.71817 This article is for general information and does not replace advice from a doctor, pharmacist or other qualified healthcare professional.
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