Estimated reading time: 4 minutes
Women who used estrogen-only hormone therapy later in life had lower odds of developing dementia and showed fewer signs of Alzheimer’s disease than women who did not use hormone therapy, according to a new study published in Neurology.
Researchers found hormone therapy users had 39% lower odds of receiving a clinical dementia diagnosis. However, they cautioned that the study identified an association and does not prove hormone therapy prevents dementia.
The findings add to growing evidence that estrogen may influence brain health, although researchers say additional studies are needed before the results can change clinical practice.
“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,” said study author Jennifer Bruno, PhD, of Stanford Medicine in Stanford, California. “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.”
More Than 21,000 Women Included in the Study
Researchers analyzed data from two large studies involving 21,462 women who entered the research at an average age of 71 and were followed for approximately three to five years. Of those participants, 1,953 had used estrogen-only hormone therapy, and 19,509 had not. Women who received hormone therapy began treatment after age 70, on average.
Researchers focused on estrogen-only hormone therapy because previous studies suggested that combined estrogen and progestin therapy may increase dementia risk. Today, estrogen-only hormone therapy is generally prescribed only for women who have undergone a hysterectomy because unopposed estrogen increases the risk of endometrial cancer.
Estrogen Therapy Linked to Fewer Alzheimer’s Disease Changes
Among nearly 3,000 women who underwent brain autopsy after death at an average age of 82, estrogen-only hormone therapy users were less likely to have the hallmark brain changes associated with Alzheimer’s disease, including amyloid-beta plaques, tau tangles, and neuritic plaques.
Researchers found:
- 18% of women who used hormone therapy had no signs of Alzheimer’s disease at autopsy, compared with 10% of women who did not use hormone therapy.
- 40% of hormone therapy users had all three Alzheimer’s disease markers, compared with 51% of non-users.
After adjusting for age, education, genetics, race, and hypertension, researchers found women who used estrogen-only hormone therapy had 35% lower odds of Alzheimer’s disease pathology at autopsy.
Biomarkers Also Pointed to Better Brain Health
Researchers also evaluated blood and spinal fluid biomarkers in a subset of participants while they were living.
Women who had used estrogen-only hormone therapy had biomarker patterns consistent with less amyloid accumulation in the brain. Higher amyloid-beta levels in blood and spinal fluid suggested less amyloid was being deposited as plaques in the brain.
Hormone therapy use was also associated with:
- Lower odds of receiving a clinical diagnosis of dementia.
- Lower risk of memory impairment.
- Lower risk of decline in functional abilities.
Findings May Not Reflect Today’s Hormone Therapy Practices
The researchers cautioned that most participants began hormone therapy after age 70. In contrast, current practice generally starts treatment during the menopausal transition, typically in the late 40s to early 50s, and ends before age 60. Because prescribing practices have changed substantially over the past several decades, the findings may not apply to women receiving hormone therapy today.
“Despite these limitations, our findings provide evidence of an association between use of estrogen-only hormone therapy during later life and better outcomes on dementia and brain health,” Bruno said.
What This Means for Nurses
Nurses in primary care, women’s health, geriatrics, and neurology are increasingly asked about the long-term effects of hormone therapy. Studies like this can help inform those conversations while reinforcing the need to distinguish between an observed association and evidence that a treatment prevents disease.
The findings suggest estrogen-only hormone therapy may be associated with healthier brain aging, including lower odds of dementia and fewer Alzheimer’s disease-related brain changes. However, it does not show that hormone therapy prevents dementia or support prescribing estrogen-only hormone therapy for that purpose.
For nurses, the findings reinforce the importance of helping patients interpret emerging research, understand its limitations, and encourage individualized discussions with their healthcare providers when considering hormone therapy.
Editor’s Note: These findings do not support starting estrogen-only hormone therapy to prevent dementia. Current hormone therapy recommendations should not be changed based on these findings alone. Women considering hormone therapy should discuss the potential benefits and risks with their healthcare provider.
