Aspirin may be linked to lower dementia risk, but bleeding danger remains

New analysis suggests that low-dose aspirin was associated with fewer dementia cases in older adults who carried a specific genetic profile. At the same time, that same group had more major bleeding, which is why the findings do not justify broad aspirin use to prevent dementia.

Researchers at Monash University examined genetic data from more than 13,500 participants in the ASPREE trial. The apparent effect showed up among people with the highest genetic scores tied to platelet count, a trait connected to the body’s clotting system.

The study, published in Alzheimer’s & Dementia, looked at whether genetics might help explain why some people respond differently to aspirin. In the original trial, aspirin did not show an overall dementia-prevention benefit when all participants were analyzed together.

Platelets are tiny blood components that cluster to help stop bleeding. Aspirin makes them less likely to clump, which can be helpful in some cardiovascular settings but also raises the risk of bleeding.

The researchers created a score based on several genetic variants associated with platelet count. They then compared dementia and bleeding outcomes in participants who had been randomly assigned to take aspirin or a placebo.

Among those in the top fifth of genetic scores, about 1% of aspirin users developed dementia, compared with 3.3% of people in the placebo group. In that subgroup, the result corresponded to an estimated 70% lower relative risk.

The absolute gap was about 2.3 percentage points, which gives a more grounded view than the relative figure alone. It reflects how many people were affected during follow-up, not a guarantee of individual protection.

Major bleeding affected 4.4% of aspirin users in the same genetic group, compared with 2.1% of those taking placebo. That also represented a difference of about 2.3 percentage points, showing that the safety issue closely matched the possible benefit.

The genetic pattern was not simply the usual Alzheimer’s risk profile. Instead, it pointed toward platelet biology, suggesting that blood-related processes may influence dementia development through another pathway.

Even so, the finding came from a subgroup analysis of an existing trial rather than a study designed specifically around this genetic signal. Results that look promising in one subgroup can arise by chance or be weaker in a different population.

The researchers say the pattern needs independent confirmation and, eventually, a trial in people selected for this profile. Genetic scores associated with platelet count should also not be confused with a routine blood test taken on a single day.

The work points to the possibility of more personalized prevention research, while also showing how difficult the balance can be. Any future advantage would need to outweigh serious bleeding, and the evidence is not strong enough to support aspirin as a dementia-prevention treatment.

If you are interested in this topic, please read articles about Mediterranean diet could help protect against Alzheimer’s, even for those at high genetic risk, and Mediterranean diet linked to lower dementia risk.

For more information, please see articles about Food, vitamins, and brain health: what we know, and 7 simple habits that may lower your risk of dementia.

Source: Monash University.