A study by the American Academy of Neurology suggests that taking a low-dose aspirin once per day does not reduce the risk of thinking and memory problems caused by mild cognitive impairment or possible Alzheimer disease. It also does not slow the rate of cognitive decline, according to the study authors.

Researchers have hypothesized that aspirin may be beneficial to the brain because of its benefits to the heart, which could possibly reduce the risk of dementia by diminishing inflammation, minimizing small clots, or by preventing the narrowing of blood vessels within the brain.

The study included 19,114 participants who did not have dementia or heart disease, with a majority of participants aged 70 years or older. Thinking and memory tests were given at the start of the study and during follow-up visits.

Half of the participants were given daily 100 milligram low-dose aspirin while the others were given a daily placebo. The participants were followed for an average of 4.7 years with annual in-person examinations.

Over the course of the entire study, 575 people developed dementia; however, researchers found no difference between those who took aspirin and those who took the placebo in the risk of developing mild cognitive impairment, dementia, or probable Alzheimer disease. In addition, there was no difference in the rate of cognitive change over time.

“While these results are disappointing, it is possible that the length of just under five years for our study was not long enough to show possible benefits from aspirin, so we will continue to examine its potential longer-term effects by following up with study participants in the coming years,” said study author Joanne Ryan, PhD, in a press release.

The only limitation found in the study was that only moderately healthy people were enrolled, and this population may benefit less from aspirin than the general population, according to the study authors.

Study: an aspirin a day does not keep dementia at bay [news release]. Minneapolis, MN; American Academy of Neurology: March 25, 2020. https://www.aan.com/PressRoom/Home/PressRelease/3785. Accessed March 27, 2020.