A new study has identified a significant reduction in grey matter volume in the brains of post-menopausal women, potentially explaining why they face a substantially higher risk of dementia later in life compared to men.
Published in Psychological Medicine, the research analysed data from 124,780 women to investigate how menopause affects brain structure and cognition, and whether hormone replacement therapy (HRT) can help mitigate these changes.
Participants were divided into three groups: pre-menopausal women, post-menopausal women who had never used HRT, and post-menopausal women who were current or past HRT users.
Researchers gathered information through questionnaires on sleep, mood, and fatigue, alongside cognitive tests measuring memory and reaction speed.
Approximately 11,000 participants also underwent MRI scans to examine physical changes in the brain.
The average age at which menopause began was 49, with most women on HRT starting the treatment around the same age.
After the analysis, researchers found significant reductions in the volume of grey matter among post-menopausal women.
The changes were most noticeable in the hippocampus, which plays a key role in learning and memory, the entorhinal cortex, which is important for memory formation and spatial navigation, and the anterior cingulate cortex, which helps with attention and emotional regulation.
Barbara Sahakian, the study’s senior author, disclosed that the brain changes observed during menopause affect areas commonly linked to Alzheimer’s disease, which could help explain why dementia is more common in women later in life.
“The brain regions where we saw these differences are ones that tend to be affected by Alzheimer’s disease,” Sahakian, a professor from Cambridge University, said.
“Menopause could make these women vulnerable further down the line. While not the whole story, it may help explain why we see almost twice as many cases of dementia in women than in men.”
The impact of menopause on cognition — including thinking, attention, language, learning and memory — has already been documented, the researchers noted.
To examine the role of hormones, the study compared pre-menopausal women with post-menopausal women, dividing the latter group into those who had used hormone replacement therapy (HRT) and those who had never used it.
The findings showed that post-menopausal women who were not on HRT had slower reaction times compared to women who had not yet reached menopause or those using HRT.
However, no significant differences were found in memory task performance across the three groups.
The study also found that post-menopausal women were more likely to report insomnia, shorter sleep duration and increased fatigue.
Women on HRT reported feeling the most tired, despite sleeping about the same amount as post-menopausal women not using HRT.
Overall, all post-menopausal women said they felt more tired than those who had not yet gone through menopause.
Katharina Zuhlsdorff said menopause may speed up the natural slowing of reaction times, but HRT seems to help slow this effect
“As we age, our reaction times tend to get slower – it’s just a part of the natural ageing process and it happens to both women and men,” she said.
“You can imagine being asked a question at a quiz – while you might still arrive at the correct answer as your younger self, younger people would no doubt get there much faster.
“Menopause seems to accelerate this process, but HRT appears to put the brakes on, slowing the ageing process slightly.”
Meanwhile, Christelle Langley, co-researcher, urged women to maintain a healthy lifestyle, staying active, exercising, and eating well, to help ease menopause’s impact on the brain.
“Most women will go through menopause, and it can be a life-changing event, whether they take HRT or not,” she said.
“A healthy lifestyle – exercising, keeping active and eating a healthy diet, for example – is particularly important during this period to help mitigate some of its effects.”
