Platelet-related genetics may separate aspirin responders from nonresponders in dementia prevention
A low-cost drug long used for cardiovascular prevention has turned up a more selective signal in brain health. In a Monash University analysis drawn from the ASPREE trial, low-dose aspirin was associated with a 70% lower relative risk of dementia among older adults with a specific genetic profile tied to platelet count. The same analysis also showed a clear safety trade-off: major bleeding occurred more often in aspirin users within that subgroup than in those given placebo.
The work, published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, adds a layer of precision to a question that has frustrated researchers for years. Earlier trials did not show an overall dementia-preventive effect when all participants were analyzed together. Here, the signal appeared only after investigators examined polygenic scores linked to platelet count, suggesting that a biologically defined subgroup may be driving the benefit.
A one-size-fits-all answer may be the wrong question.
The strongest signal appeared in the highest platelet genetic score group
The analysis drew on genetic data from more than 13,500 participants in ASPREE, the large randomized study of aspirin in older adults. Researchers examined whether differences in genes related to platelet count could modify aspirin’s effect on dementia risk. Platelets do more than stop bleeding; they also contribute to clot formation and have been implicated in platelet activation and aggregation, processes already linked to neurovascular injury and dementia biology.
Among participants in the highest 20% of platelet count genetic scores, 1% of aspirin users developed dementia compared with 3.3% of those taking placebo. Framed as a relative measure, that translated to about a 70% lower risk in the aspirin arm within that genetic stratum. The pattern is hard to ignore because it emerged in a subgroup selected by biology rather than by age, symptom burden, or a post hoc clinical label.
The same subgroup carried the safety signal into sharper view. Major bleeding affected 4.4% of aspirin users versus 2.1% of placebo recipients. For an antiplatelet drug, this is not a side issue; it is the central trade-off. Any prevention strategy built on aspirin has to account for hemorrhagic harm at the same time it weighs possible cognitive protection.
Platelet biology may explain why aspirin has looked inconsistent in dementia trials
Lead author Dr. Peter Fransquet framed the result as a clue that genetic makeup could eventually shape dementia prevention choices. He pointed to the fact that previous trials found no benefit when everyone was analyzed together, then described the new findings as evidence that some people may sit on a different side of the aspirin response curve. The striking part is not simply the magnitude of the association, but the biological pathway it seems to implicate.
The genetic signal did not map onto the established risk factors commonly tied to Alzheimer’s disease and other dementias. Instead, it pointed toward platelet biology. That matters because platelets can influence vascular integrity, microthrombotic burden, and inflammatory signaling, all of which may affect the brain over years rather than weeks. In an older population, where cerebrovascular disease and mixed dementia are common, a small change in platelet behavior could plausibly have downstream effects on neural injury.
This may also help reconcile why aspirin has appeared neutral in broad dementia-prevention studies while still showing hints of benefit in narrower analyses. When a treatment acts through a mechanism that only matters in a biologically selected subgroup, an average trial result can flatten out into apparent no effect. The average hides the responders.
Clinical use still hinges on bleeding risk and validation in new cohorts
The findings do not justify starting aspirin solely to prevent dementia. That point comes through clearly in the caution attached to the study: people should not take aspirin for this purpose without medical advice, especially because serious bleeding increased in the same genetic group that appeared to benefit cognitively. The signal is promising, but it is still an observational genetic interaction layered onto a randomized trial, not a practice-changing treatment trial in a preselected genotype.
Before any clinical recommendation can move forward, the association needs to be reproduced in other populations. A dedicated trial would also be needed, one that enrolls people with the genetic profile identified here and tests whether aspirin truly lowers dementia incidence while keeping bleeding risk within acceptable bounds. Without that kind of confirmation, the result remains hypothesis-generating, even if the biology is compelling.
Dementia prevention needs strategies that are both effective and safe enough for broad use. In Australia, Dementia Australia estimates that about 446,500 people are living with the condition in 2026, with that number projected to rise above one million by 2065. The pressure to find preventive options is obvious, but so is the danger of overextending a drug with well-known hemorrhagic toxicity.
Cheap, accessible aspirin could still prove useful in a personalized prevention strategy. For now, the central message is narrower: a platelet-related genetic signature may identify older adults who are more likely to gain cognitive benefit from aspirin, but the bleeding penalty remains real and the finding still needs independent confirmation before it can alter routine care.