The Link Between Menstruation and Dementia: New Study Reveals Fascinating Connection
The ages at which a person starts and stops menstruating could impact their risk of developing dementia later in life, according to the largest study of its kind.
The analysis included health information from 273,260 female participants in the United Kingdom Biobank, and the findings suggest that those who start their period younger and go through menopause older have healthier aging brains, relatively speaking.
Decreased Dementia Risk
Specifically, researchers at University College London found that people who menstruated for 34 to 37 years had a 28 percent decreased risk of dementia compared to those with a shorter ‘reproductive span’.
This correlation seemed to depend both on when menstruation started and when it stopped, either naturally or from reproductive surgery.
Hormone Levels and Brain Aging
In humans, estradiol is the most potent of the estrogen family of hormones. Its level ebbs and flows throughout life, peaking during reproductive years and declining with menopause.
The current study uses menstruation as a proxy for these hormone levels. Participants who started menstruating at age 15 or older showed a 12 percent increased risk of dementia. Meanwhile, those who experienced menopause after the age of 50 had a 24 percent decreased risk for dementia.
Hormone replacement therapy, which supplements estrogen after menopause, didn’t seem to impact the results. The associations were also consistent among people who carried genetic risk factors for dementia and those who did not.
Evidence from Previous Research
For instance, in postmortem brains of women who died with Alzheimer’s disease – the most common form of dementia – scientists have measured relatively low estrogen levels.
Follow-up animal studies have revealed that the mammal brain is highly sensitive to estrogens, especially in regions associated with learning and memory.
Study Reveals Cumulative Estrogen Exposure and Brain Aging
To tease apart these mixed results, researchers at University College London conducted the largest analysis to date. Their findings suggest that cumulative estrogen exposure in life is tightly linked to healthy brain aging.
Reproductive Surgery and Dementia Risk
One of their more concerning findings is that people who underwent reproductive surgery faced an 8 percent increased risk of dementia.
Thankfully, it seems that this risk can be significantly ameliorated if the surgery is done later in life (in a patient’s 40s or 50s as opposed to their 20s or 30s).
Considerations for Clinical Practice
“When women undergo surgery due to such benign conditions, they go through an abrupt decrease in estrogen exposure and accelerated changes in the nervous system in the perimenopausal period,” researchers at University College London explain.
“[R]eproductive surgery should be considered as an increased risk for dementia in clinical practice.”
The Need for Further Research
The current analysis has produced some of the most robust observational results to date, but it can only reveal associations at a population level.
Far more research is needed to say how estrogen might directly impact brain aging and what we can do about it. There’s even a chance other sex hormones, like progesterone, are also playing an overlooked protective role.
While the current study did not show improved cognitive health outcomes among those who received hormone replacement therapy, some researchers in the past have theorized that it is the timing of these treatments that matter to brain health, not just whether or not they occur.
Conclusion
Far more research is needed to determine why females tend to develop dementia at higher rates than males, and how that risk can be reduced.
If we are to truly understand cognitive decline, experts say prioritizing female brain studies in the future is a must.
Study Publication
The study was published in The American Journal of Geriatric Psychiatry.
