A recent study published in the Alzheimer’s Association found that women who have their ovaries removed before turning 40 or hitting menopause can face a decline in cognitive health later in life, likely due to the sudden loss of critical sex hormones.

When women have their ovaries removed before menopause, a procedure known as premenopausal bilateral oophorectomy (PBO), they lose crucial hormones such as estrogen, progesterone and testosterone, which can cause a number of health issues.

Previous research has shown that women with PBO are more likely to develop memory issues and dementia, but not many brain scans have been done to understand why.

One study revealed that women with PBO had smaller brain regions involved in memory and emotions and another showed these women had smaller hippocampal, the region associated with memory, volumes soon after surgery.

Animal studies and human comparisons also suggest that losing these hormones affects brain white matter, especially in women who have PBO at a younger age.

Researchers of the Alzheimer’s Association study examined cognitive aging among 1,011 women 50 years and older with and without PBO before menopause, who also had MRI brain scans and were enrolled in the Mayo Clinic Study of aging (MCSA).

MCSA is a population-based cohort study of cognitive aging done in 2004 among women in Olmsted County, Minnesota.

Researchers used medical records to find details about the women’s surgeries and hormone treatments. They also gathered information such as age, education and health conditions.

Brain scans were analyzed to measure white matter integrity, and statistical tests were used to find differences between the groups.

After comparing women who had PBO before age 40, between 40 and 44 and 45 through 49 with women who didn’t have the surgery, researchers found that women who had PBO before age 40 had worse white matter in several brain areas compared to those who didn’t have the surgery.

Specifically, these women had lower FA (a measure of brain health) in areas such as the anterior corona radiata and superior temporal white matter. They also had higher mean diffusivity MD (another brain health measure) in regions such as the corona radiata and superior occipital white matter.

Women who had PBO between 45 and 49 years old also showed lower FA and higher MD in some brain regions compared to those without the surgery.

The study didn’t find differences in brain health for women who had PBO between 40 and 44 years old.

Other factors including genetics, heart health, hormone use and pregnancy didn’t change the results.

Findings suggests that losing ovaries and the hormones they produce before 40 can negatively impact brain health, potentially leading to worse cognitive outcomes later in life.

As this study explored the subject further, it was strengthened using detailed medical records to confirm PBO and track estrogen replacement therapy (ERT) use. The study focused on how PBO affects brain health and compared different age groups, showing consistent results even after adjusting for various factors.

However, there are some limitations including the study may have missed some women with PBO who were too sick to join, most participants were white and it didn’t adjust for all comparisons since it was exploratory.

In addition, it couldn’t account for different hormone exposures before surgery and had limited info on hot flashes.

Most women in the study used ERT, making it hard to see the true impact of PBO alone.