Having a hysterectomy may cause short-term memory loss in a third of patients over 60, suggests first study to link the womb and the brain
- Nearly one-third of women in the US have a hysterectomy to remove the uterus by age 60 – but most surgeries are not ‘medically necesary’
- The prevailing medical theory is that the uterus’s only function is for reproduction, making it useless after menopause
- But a new Arizona State University study is the first to suggest that is false
- Removing just the uterus of a rat led to short-term memory problems
- Surgery to take out just the ovaries or ovaries and uterus both did not
- This suggests a direct link between cognition and the uterus
Having a hysterectomy may increase women’s risk of developing dementia, according to new research.
Undergoing a hysterectomy to remove the uterus triggers menopause. After the surgery, many say they notice a change in their cognition, or ‘brain-fog.’
Scientists have struggled to establish a clear connection between hysterectomies, menopause and mental function.
But the new study, from Arizona State University (ASU), is the first to establish a direct link between the womb and the brain.
In experiments with rats, the researchers there found that the removal of the uterus alone – but not the ovaries – may well cause short-term memory and cognition problems.
Having a hysterectomy may cause memory loss for the third of American women who have had the procedure, a new study suggests
We are in the age of mind-body medicine, where mental health is finally accepted as part and parcel of overall physical health, and the make-up of our guts is acknowledged as influencing our mood.
This revelation complicated notions old and new – especially when it comes to women’s health.
Some mental health issues like depression that were once dismissed as ‘hormonal swings’ when they affected women are now understood to be more complicated.
At the same time, so long as the mechanisms behind changes women notice – such as cognitive problems after menopause – have remained unknown, doctors have hesitated to treat them.
Similarly, research has come down on both sides of the debate over whether hormone replacement therapy (HRT) raises risks of dementia or not.
Given these related, but sometimes conflicting, bits of knowledge and uncertainty, ‘we wanted to investigate and understand whether the uterus itself could impact brain function,’ says senior study author Dr Heather Bimonte-Nelson, an ASU psychologist.
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While the uterus is a crucial part of female anatomy during a woman’s reproductive years, the prevailing theory in the scientific community has long been that the organ serves no function after menopause.
But the new study, published in the journal, Endocrinology, turns that notion on its head.
‘Our novel findings indicate the non-pregnant uterus is not dormant and is in fact linked to brain function,’ says Dr Bimonte-Nelson.
‘This finding is striking.’
Nearly a third of all women in the US have a hysterectomy by age 60 – and some research suggests that most of these are not medically necessary and are done preventatively to treat conditions for which there are less invasive options.
So elective surgery may actually be hampering the minds of hundreds of thousands of women a year.
It seems that we don’t know as much as we believed about the female reproductive system’s role in whole-body health – though we’re starting to learn.
‘There is some research showing that women who underwent hysterectomy but maintained their ovaries had an increased risk for dementia if the surgery occurred before natural menopause,’ Dr Bimonte-Nelson says.
WHAT IS A HYSTERECTOMY?
A hysterectomy is a surgical procedure to remove a woman’s uterus.
There are three kinds:
- PARTIAL HYSTERECTOMY: Removes two-thirds of the uterus.
- TOTAL HYSTERECTOMY: Removes uterus and cervix.
- RADICAL HYSTERECTOMY: Removes uterus, cervix and vagina.
The operation is most commonly performed on women between the ages of 40 and 49.
More than 20 million American women have had a hysterectomy, according to data from the Centers for Disease Control and Prevention.
As women approach menopause, the odds that they will develop one of several serious uterine health conditions increases. Doctors may recommend a hysterectomy as a treatment for:
- uterine (endometrial) cancer
- chronic uterine pain or bleeding
- collapsed uterus
In some cases, doctors may suggest a hysterectomy as a preventative measure if a woman has significant warning or early signs of developing one or more of these conditions.
When necessary, surgeons may also remove the ovaries and fallopian tubes, if these have also been damaged or are at serious risk of damage.
The removal of reproductive organs sends a woman’s body into menopause, no matter how old she is.
This comes with unpleasant side effects like hot flashes, and many women have to start hormone therapy, taking estrogen to balance out their own hormones.
But she an her team suspected that the uterus played a role too. So they tested their theory by performing a variety of menopause surgeries on rats.
The rats were divided into four groups which had either the uterus and ovaries both removed, one or other, or none at all during a dummy procedure.
Six weeks after surgery, the researchers taught them how to navigate a water maze that looked like a sunburst, with eight arms radiating out from a circular center.
The maze involved four platforms that the researchers removed when the rats found them.
The fewer platforms that remained, the greater the demand was on the rat’s memory because they had to recall both where the missing platforms had been, and where there had never been a platform.
With two platforms down and two to go, the research team found the rats that had only the uterus removed could not handle the increased memory load.
These rats kept returning to places where there had never been a platform, indicating they were unable to remember which arms of the maze led to platforms.
The other kinds of surgery did not affect how many mistakes the rats made in the maze.
First author Stephanie Koebele, a graduate student, explained: ‘The surgical removal of just the uterus had a unique and negative effect on working memory, or how much information the rats were able to manage simultaneously, an effect we saw after the rats learned the rules of the maze.’
‘We found that a hysterectomy may impair short-term memory in rats,’ Dr Bimonte-Nelson explains.
This suggests that the uterus and ovaries are part of a system which communicates with the brain for functions such as cognition.
We know they communicate for reproductive functions, but there are also direct connections between the womb and the brain through the body’s autonomic nervous system, which coordinates unconscious functions like breathing.
But the discovery of this more complicated link to cognition suggests the womb could affect cognitive functions and impact how females age.
Dr Bimonte-Nelson said: ‘We hope these basic science findings will lead to more attention around how different menopause surgeries might impact the brain and its functioning in women, ultimately impacting their quality of life.’
Donna Korol, an associate professor of biology at Syracuse University, New York, who was not part of the study, said its protocol adds weight to the results.
She said: ‘This experiment tests the role of the uterus in cognitive changes that accompany menopause.
‘The researchers use several surgical approaches that are actually used for women who undergo oophorectomy (surgical removal of the ovaries), hysterectomy, or both. This alone is laudable.
‘One of the beauties of this experimental design was the sampling of different measures from the same rat, allowing for within-animal comparisons across multiple systems.’
The finding could also shed light on why women are twice as likely as men to develop dementia.
‘Even though the ovaries were structurally similar across all the groups, the hormones that were produced in the group that received hysterectomy alone resulted in a different hormone profile,’ said Koebele.
‘Hormones affect both brain and other body systems, and having an altered hormonal profile could impact the trajectory of cognitive ageing and could create different health risks.’
Exactly how the altered hormone profile affects cognitive ageing or creates health risks is complicated but is nonetheless very important to study and understand.
Dr Bimonte-Nelson said: ‘Complicated does not mean impossible.’
Her lab is currently testing whether the memory deficit after hysterectomy is reversible with time or is the beginning of a more global memory impairment
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