A regimen of daily, low-dose aspirin failed to produce a significant reduction in the incidence of dementia or cognitive impairment in ASCEND, a randomized, multicenter trial with more than 15,000 people with diabetes followed for an average of more than 9 years, but the results hinted at enough of a benefit to warrant further study, some experts said.
“The question remains open,” said, as she presented the findings at the American Heart Association scientific sessions. “The rate ratios suggest some benefit. It’s encouraging,” added Dr. Armitage, professor of clinical trials and epidemiology at Oxford (England) University.
The study tallied dementia outcomes three different ways: It applied a narrow definition that relied on a specific diagnosis of dementia in a person’s EHR or in their death record. (Dr. Armitage and her associates tracked outcomes for 99% of the enrolled participants by linking to their U.K. national health records and death records.)
A second metric used a broader outcome definition that tracked EHR entries for not only dementia but also diagnoses of cognitive impairment, delirium, confusion, prescription of dementia medications, and referral to a memory clinic or geriatric psychiatry. The third assessment was a cognitive-function test given to participants at the end of follow-up, but only 58% of enrolled participants completed this part of the study, and it’s also possible that some subjects missed this assessment because of dementia onset. These limitations hamper clear interpretation of this third metric, Dr. Armitage said.
The main findings for the other two, more reliable measures of incident dementia or cognitive deterioration showed a nonsignificant 9% relative risk reduction linked with aspirin use compared with placebo for the more inclusive endpoint, and a nonsignificant 11% relative risk reduction with aspirin using the narrow definition for dementia only, she reported. The third method, a directly administered assessment of dementia and cognition, also showed a small, nonsignificant effect from daily aspirin use relative to placebo.
Results can’t rule out modest aspirin effect
Dr. Armitage highlighted that the two more reliable measures both appeared to rule out risk for neurologic harm from aspirin because the upper limit of the 95% confidence interval for relative effect reached only 1.02 using the broad outcomes, and 1.06 for the narrower endpoint of dementia only. On the other hand, focus on the low end of the 95% confidence interval suggested potentially meaningful benefits, with a possible reduction by aspirin in events relative to placebo of as much as 19% by the broad outcome definition and by 25% with the narrow definition.
“Even if it was only a 15% relative risk reduction, that would be important,” given the high dementia incidence worldwide, Dr. Armitage said during a press briefing. “It’s entirely possible, with our results, that a modest benefit exists.”
This take on the findings won some support. Further studies with more people, longer follow-up, and perhaps enrolling a more selected, higher risk cohort may better address potential neurologic benefit from aspirin, suggested, a stroke neurologist and professor of neurology at the University of Southern California, Los Angeles, and a designated discussant for the report.
The result “was rather encouraging. I was a little surprised” by the findings, commented, professor and director of the Center for Cardiometabolic Disease Prevention at Baylor College of Medicine, Houston, also a discussant.
The results “don’t mean that no one benefits from aspirin. Perhaps certain people at risk would benefit from dementia protection. It’s an open question,” commented, director of Women’s Cardiovascular Health at Johns Hopkins Medicine, Baltimore.
But others saw the findings as more unequivocally neutral. “This gives us an early, preliminary answer, that aspirin does not seem to improve dementia,” commented, professor and director of Preventive Cardiology at UT Southwestern Medical Center, Dallas, and a third discussant at the meeting.
Evidence against routine, widespread primary prevention with aspirin
had the primary goal of assessing a daily, 100-mg aspirin dose for its safety and efficacy for preventing vascular events such as MIs and ischemic strokes in 15,480 people with diabetes who were at least 40 years old at enrollment and had no history of cardiovascular disease. The came out in 2018 and showed that while aspirin produced a significant benefit by reducing thrombotic events, it also resulted in significantly more major bleeding events compared with placebo, and overall the magnitude of benefit roughly matched magnitude of risk.
These findings, along with similar results from two other high-profile aspirin studies reported at about the same time (, and ), led to recommendations from groups like the and from the and American Heart Association that caution against widespread, routine aspirin use for primary prevention of atherosclerotic cardiovascular disease events in most adults.
The groups instead endorsed a tailored strategy of targeting aspirin to people with a higher than average risk for ischemic thrombotic events and a lower than average bleeding risk. (The most recent aspirin recommendations from the USPSTF, currently inform, substantially curtail aspirin’s appropriate use, eliminating it in those over age 60 years.)
However, experts and prevailing practice recommendations continue to endorse routine aspirin use for secondary prevention in patients with an established history of cardiovascular disease.
The new findings reported by Dr. Armitage came from additional analyses of dementia and cognitive impairment overlaid on the main ASCEND outcome analyses. ASCEND actively treated and followed study participants for an average of 7.4 years, then researchers tracked further dementia outcomes based on medical-record entries for an average of another 1.8 years.
ASCEND received partial funding or support from Abbott, Bayer, Mylan, and Solvay. Dr. Armitage had no disclosures. Dr. Towfighi, Dr. Khera, and Dr. Michos had no disclosures. Dr. Ballantyne has had financial relationships with numerous companies.