Monash University analysis linked low-dose aspirin to a 70 percent lower relative dementia risk in older adults with a specific genetic profile, while also finding higher major bleeding in that group. The study used genetic data from more than 13,500 participants in the ASPREE Trial and was published in Alzheimer's & Dementia: The Journal of the Alzheimer's Association.
Researchers compared people given aspirin with those given a placebo after assigning genetic scores tied to platelet count. Among people in the highest 20 percent of those scores, 1 percent of aspirin users developed dementia, compared with 3.3 percent of placebo users.
Monash University and ASPREE
The analysis focused on whether genetic variation related to platelet levels could help explain why aspirin might affect dementia risk differently from one person to another. The strongest results involved genes associated with platelet count, which is where the 70 percent lower relative risk emerged.
Dr. Peter Fransquet, a Research Fellow at Monash's School of Public Health and Preventive Medicine, said the study points away from a blanket approach. He said, "Previous trials found aspirin didn't prevent dementia when everyone was considered together," and added, "Our findings suggest there may be more to the story."
Platelet Count Genetic Scores
Fransquet said, "In people with this particular genetic profile, we saw substantially fewer cases of dementia among those taking aspirin." He also said, "It raises the possibility that genetics could one day help us identify who may benefit from a preventive treatment, rather than taking a one-size-fits-all approach."
The same genetic group that showed fewer dementia cases also had more major bleeding. In the highest 20 percent of platelet count genetic scores, 4.4 percent of aspirin users experienced major bleeding, compared with 2.1 percent of those receiving a placebo.
Australia and Dementia Australia
Dementia Australia estimates that approximately 446,500 people in Australia are living with dementia in 2026, and expects that number to exceed one million by 2065. The study leaves a practical choice for older adults and their doctors: the subgroup that appeared to benefit from aspirin also carried a higher bleeding rate, so any use as prevention would need to weigh both outcomes together.
