Later-life estrogen therapy associated with lower risk of developing dementia

Use of hormone therapy later in life was associated with lower risk of developing dementia, according to a study published August 12, 2026, in Neurology®, the medical journal of the American Academy of Neurology.

While these findings help us better understand the relationship between hormone therapy use and various markers of dementia, more research needs to be done before we can make recommendations to women about their use of these therapies in relation to their brain health. This study looked back at women who were using hormone therapy decades ago with the timing and type of use differing from what is current practice for most women today, so the results are informative, but they may not apply to today's standards."

For the study, researchers examined medical records from two large data sets. In total, the study reports data from 21,462 female participants from both groups who had clinical tests taken while they were living. A total of 728 participants from one data set completed brain scans or biomarker tests while they were living and 2,959 participants from the other data set had autopsies after death, at an average age of 82, to look for signs of Alzheimer's disease. Across both data sets, participants were followed for approximately three to five years, starting at an average age 71.

Of the total participants, 1,953 participants took hormone therapy and 19,509 participants did not take hormone therapy. Those who used hormone therapy started using it when they were over age 70, on average. The researchers looked only at participants who took estrogen-only therapy, since previous studies had indicated that estrogen plus progestin combination therapy may increase the risk of dementia. In current standard practice, estrogen-only therapy is prescribed only for those who have undergone a hysterectomy due to the risk of endometrial cancer.