A new study suggests that women who use a popular hormonal menopause treatment later in life may be at a higher risk of developing Alzheimer’s disease, a neurodegenerative condition that affects an estimated 7 million Americans.
Researchers from Mass General Brigham found that women treated with hormone replacement therapy in their sixties were much more likely to develop Alzheimer’s in their 70s.
The most common type of dementia, Alzheimer’s is caused by a buildup of amyloid proteins in the brain, with risk factors including age, family history, unhealthy lifestyle behaviors, and certain medical conditions.
The results of the study, published in Science Advances, found that women over 70 who took menopausal hormone therapy had faster accumulation of tau, a naturally occurring protein that helps stabilize nerve cells.
Along with another protein, amyloid beta, tau can build up in the brain and disturb cell function. Abnormal clumps of tau called neurofibrillary tangles are a hallmark of Alzheimer’s.
Women who had taken HRT had higher levels of plaque compared to their peers who had never taken it.
Further, researchers found that younger women who stopped taking HRT in their 50s and early 60s did not exhibit the same risk.
Based on these findings, the team notes that women who have been menopausal for over ten years without treatment should not be prescribed HRT.
“Approximately a quarter of currently postmenopausal women who are 70 years and older have a history of HT use and have now entered a critical age of risk for Alzheimer’s disease,” said senior author Rachel F. Buckley, PhD, of the Department of Neurology at Massachusetts General Hospital.
“Our findings add to the evidence that delaying initiation of HT, especially in older women, could lead to worse Alzheimer’s outcomes.”
Around twice as many women have Alzheimer’s disease than men.
Experts believe that while some of this may be because women live longer on average, the decline in estrogen levels that occurs during menopause could also play a role, given that estrogen is essential for cognitive function.
For the latest study, researchers recruited 146 women, with an average age ranging from 51 to 89 at the onset of the study. The team compared brain imaging from 73 women who had used hormone therapy an average of 14 years prior and 73 who had not.
PET scans were used to check for amyloid beta and tau tangles.
Women over 70 who used hormone therapy demonstrated faster tau buildup in the areas of the brain linked to memory and recognition compared to women of the same age who had not used the treatment.
Tau accumulation linked to cognitive decline was only exhibited in HT users, indicating that tau buildup contributes to cognitive impairment.
Interestingly, in women under 70, the use of HT seemed to guard against tau buildup in the areas of the brain associated with memory, with no significant cognitive issues reported in non-users.
The team is uncertain if the faster buildup in older HT users is due to when they started therapy or if older patients naturally exhibit more tau buildup in PET scans.
Current clinical guidance maintains that HT should be initiated within 10 years following a woman’s age at menopause to avoid adverse effects.
“Our findings add to the evidence that delaying initiation of HT, especially in older women, could lead to worse Alzheimer’s outcomes. We hope that our study will help to inform risk discussions relating to women’s reproductive health and treatment,” said Dr Gillian Coughlan, first author of the study.
There is no known cure for Alzheimer’s, but certain medications can help slow the cognitive decline that’s characteristic of the disease.
Cognitive assessments, brain scans and blood tests are often used to diagnose Alzheimer’s because no single test is definitive.
Studies have shown six lifestyle habits — exercising, not drinking or smoking, getting enough sleep, socializing and having hobbies — can slash your risk of developing dementia.
