Dementia risk in women linked to common invasive surgery that can cause cognitive decline

Women who have had a common but invasive surgery before they reach the menopause could be at a higher risk of developing dementia and experiencing a general decline in their cognitive function, a new study suggests. The prevalence of all forms of dementia is higher in women, with twice as many cases of Alzheimer's disease as men.

This new research could help scientists to better understand some of the underlying risk factors that make women more likely to experience these neurodegenerative diseases. The study examined the brains of women who had undergone surgery to remove their ovaries before they reached the menopause and found a marked decrease in their brain health.

Declining amounts of your brain's white matter cause cognitive decline and are closely associated with the effects of dementia. Examining the MRI results of more than 1000 women, researchers at Wake Forest University found a link between the brain-wasting disease and women who had their ovaries taken out, a procedure called a Bilateral Salpingo Oophorectomy (BSO).

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Women typically undergo this surgery pre-menopause to prevent the future risk of developing ovarian cancer, which kills more than 4000 Brits every year. Other reasons can include endometriosis and ovarian cysts, but this new research suggests this regular procedure could have a knock-on effect on your brain years later.

When a person has their ovaries removed, this changes the hormone cycle within their body, something that does not tend to happen until the onset of menopause. Professor Michelle Mielke at WFU wanted to see if this previously spotted link between hormone production and cognitive decline could also be seen in women who have had BSO.

What does all of this mean?

Your brain is composed of two different kinds of matter, grey and white. To simplify, your grey matter is largely responsible for your movement and some other brain functions, including memory, while your white matter communicates information and signals across your brain and to your nervous system.

Both of these parts of your brain are known to shrink with age, but can be severely affected if you develop a form of dementia. Some like Alzheimer's disease will mostly affect the grey regions of your brain, while others can cause your white matter to severely shrink - causing a decline in your ability to think.

The study found that ovary removal was strongly associated with those whose white matter had started to shrink. Going through a BSO causes an "abrupt endocrine dysfunction. as a result of removing the ovaries" Something study lead Professor Mielke wanted to explore further.

Of the 1011 MRIs, each patient was broken down by age group and whether they had an ovary removal surgery. The vast majority (907) had not had a BS0, while 22 had the procedure under the age of 40, another 43 women had between 40 and 45, and 39 aged between 46 and 49 had their ovaries removed.

Cross-analysing with the large dataset of MRIs, Mielke found that those women who had a BSO before the age of 40 saw a greater decline in white matter. The professor said: "Females who had BSO before the age of 40 had significantly reduced white matter integrity in multiple regions of the brain.”

However, older women who had the procedure were less likely to see the decline in white matter, which is not the only indicator of diseases like dementia, but measuring it can be a key part of a doctor's path to diagnosis.

Dr Verna Porter has explained why having this surgery can cause a decline in your brain matter. They spoke to Medical News Today about the role of oestrogen and testosterone: “Both hormones contribute to overall brain health, influencing mood, cognition, and neuroprotection.

“Oestrogen therapy, particularly when started soon after oophorectomy and within certain therapeutic windows, may help preserve white matter integrity and cognitive function.

”Women who had their ovaries removed before age 40 showed reduced white matter integrity, which suggests an increased risk for cognitive impairment and dementia. This emphasises the critical role of ovarian hormone regulation in maintaining brain structure/ function, particularly in preserving white matter integrity."