Aspirin and Dementia: Genetic Profile Linked to Lower Risk, Higher Bleeding

A lower dementia rate came with more bleeding

A genetic signal may help explain why aspirin has not consistently reduced dementia risk in earlier trials. In an analysis of more than 13,500 older adults, Monash University researchers found fewer dementia cases among aspirin users with high genetic scores associated with platelet count. The same group also had more major bleeding, underscoring the trade-off behind any future attempt to tailor prevention by genetics. The result offers a possible explanation for why an effect in some people might be hard to detect when trial results are averaged across everyone. It doesn't show that genetic testing can yet identify who should take aspirin.

The researchers analyzed genetic data from participants in the ASPREE Trial, which compared aspirin with a placebo. They grouped participants by genetic scores linked to platelet count, then compared dementia and bleeding outcomes across the groups. A genetic score is a way of summarizing many inherited differences associated with a trait; it doesn't mean that a participant's platelet count was directly measured or that the score determines an individual's outcome. This distinction matters when interpreting subgroup results: the analysis points to a pattern worth testing, rather than a ready-made clinical screening tool.

Among participants in the top fifth of platelet-count genetic scores, dementia occurred in 1 percent of those assigned aspirin and 3.3 percent of those assigned a placebo. That amounts to an approximately 70 percent lower relative risk in the aspirin group. The gap sounds striking, but the percentages describe the results within one slice of the trial population. They don't tell us whether the same pattern would appear in another group of older adults, or how well the genetic score would predict benefit for any one person.

Major bleeding, however, was reported in 4.4 percent of aspirin users in that genetic group, versus 2.1 percent of placebo recipients. The finding therefore points to a potential benefit accompanied by a substantial safety concern; it doesn't establish that aspirin is an appropriate preventive treatment for people with this profile. The bleeding result belongs in the same conversation as the dementia result, not in the footnotes. Any future assessment would need to consider both outcomes, since a possible reduction in dementia cases doesn't erase the increased harm observed in the analysis.

Lead author Dr. Peter Fransquet, a research fellow at Monash’s School of Public Health and Preventive Medicine, said earlier trials found no dementia prevention effect when results were considered across all participants. “Our findings suggest there may be more to the story,” he said, adding that genetics might eventually help identify people who could benefit from a preventive treatment. Here's the thing: a subgroup signal can help researchers form a sharper question, but it can't settle that question on its own. The study suggests where to look next; it doesn't resolve whether the apparent benefit is reliable or clinically useful.

Platelet biology offers a new research lead

Prior studies have linked dementia with platelet activation and aggregation, the processes that cause platelets to become active and stick together. The relationship between dementia and a person’s overall platelet count has been less clear. This analysis highlights platelet-related genetics as another avenue for investigation. That makes the finding relevant beyond aspirin alone: it gives researchers a reason to examine how platelet biology might relate to dementia risk, while leaving open which mechanisms, if any, explain the pattern.

The genetic signal didn't involve established risk factors commonly associated with Alzheimer’s disease and other forms of dementia. Fransquet said that distinction makes platelet biology a particularly interesting direction for follow-up research. It also calls for care in interpreting what the score represents. A genetic association can point to a biological pathway without proving that the pathway caused the outcome, or that changing it with a medicine will prevent disease.

This is more significant than it looks as a research lead, but the evidence is still early. The genetic score grouped participants by inherited tendencies associated with platelet count; it didn't identify a treatment rule that doctors can apply. (And this is the part most people overlook.) Finding a group-level association is only one step: researchers still need to establish whether the pattern holds up and whether it can help guide decisions without exposing people to unnecessary harm.

The study’s authors say the association needs confirmation in other populations. Researchers would then need to run a clinical trial designed specifically for people with the identified genetic profile before the findings could inform medical recommendations. That sequence matters. Repeating the analysis elsewhere would test whether the signal travels beyond this study population, while a targeted trial would address whether aspirin actually changes outcomes for people selected by that profile. Until then, the results remain a prompt for research rather than a basis for treatment.

Findings aren’t a reason to start aspirin

Fransquet cautioned against taking aspirin to prevent dementia based on this analysis, particularly given the higher rate of serious bleeding. The result comes from a subgroup analysis and requires further study before its implications for individual care are clear. Aspirin's potential benefit can't be separated from its potential harm here. If you're working in this space, that balance is the central question a future study would need to answer.

The question has growing relevance in Australia, where Dementia Australia estimates that about 446,500 people will be living with dementia in 2026. The organization projects that figure will exceed one million by 2065. Those estimates describe the scale of the public health challenge; they don't demonstrate that aspirin or genetic screening would reduce it. A possible treatment signal can attract attention, but the finding still needs to survive replication and a trial designed to test the proposed approach.

If future research confirms the genetic association and tests it in a targeted trial, an inexpensive, widely available medicine could become part of a more individualized prevention discussion. That possibility is conditional, and the bleeding signal makes it especially important not to treat “personalized” as a synonym for safer. What this means for you is straightforward: the study gives researchers a specific hypothesis to pursue, while offering no reason to begin aspirin for dementia prevention. A promising lead, with a clear cost to investigate.

Materials provided by Monash University. Note: Content may be edited for style and length.

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