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Dr. Jennifer Rabin of the Sunnybrook Research Institute worked on the research related to the menopause transition and women’s brain health.Yuri Markarov/Supplied
It’s a scientific mystery that puzzles researchers: Why are more Canadian women than men diagnosed with Alzheimer’s disease and other dementias?
That population demographic made up an estimated 62 per cent of people living with dementia in Canada in 2020, according to the Alzheimer Society of Canada.
But new scientific research conducted by Canadian scientists is shedding light on how changes that unfold in menopause could affect the brain later in life. It could also set the stage to uncover why women are disproportionately affected by neurodegenerative disease.
Late last month, research led by scientists at Sunnybrook Research Institute was published in the journal Nature Medicine on how menopause-related biological changes involving the brain are detected in the blood and could be linked to cognitive decline later.
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Separately, Natasha Rajah, a researcher at Toronto Metropolitan University, is leading Canada’s only brain-imaging study on how biological sex, menopause and dementia risk factors affect memory-related brain function in midlife.
The study, part of TMU’s Brain Health Equity in Aging and Memory Lab, has produced papers on memory, brain aging and dementia prevention documenting findings of age-related decline in perimenopausal and postmenopausal women and a link to poor vascular health and memory in the postmenopausal period.
Dr. Rajah hopes, in the long-term, her research will offer insights on what is happening to women in menopause to help identify behaviours or interventions to support them.
Jennifer Rabin, a clinical neuropsychologist and scientist with the Hurvitz Brain Sciences Program at Sunnybrook Research Institute and the Temerty Faculty of Medicine at University of Toronto, said the fact women tend to live longer than men does not explain the disparity.
“All women who live long enough go through menopause, and not all women develop Alzheimer’s disease,” Prof. Rabin said.
“In fact, many more don’t develop Alzheimer’s disease than do. So it can’t just be menopause. But I do think that there is something about menopause that is happening that definitely puts some women on a different trajectory.”
Their research underscores broader questions, such as how menopause affects the brain and how it affects women’s risk for Alzheimer’s disease and other neurodegenerative disorders later on.
“We know that women are at increased risk for Alzheimer’s disease,” Prof. Rabin said. “We know that the pathology associated with Alzheimer’s disease actually starts developing in midlife.”
Prof. Rabin worked with a postdoctoral candidate that she is supervising, Madeline Wood Alexander, who was the lead author on the research.
Their findings suggest the menopause transition may offer key insights on how biological changes in midlife relate to women’s brain health and dementia risk later.
“We think it’s a really important window to study, to have our best chances of developing preventative strategies and optimizing brain aging for women,” she said.
The scientists used blood to test for hundreds of different molecules in 80 women aged 43 to 58 separated into groups according to their stage of menopause: pre-, peri- and postmenopausal.
The findings found differences in the blood of postmenopausal women, such as higher levels of inflammation, compared to pre- and perimenopausal women.
The researchers also tested their results against data from another study, the UK Biobank, which included 2,814 women age-matched between the pre-to-perimenopausal and postmenopausal periods, between ages of 45 and 60. They found the same menopause-related shifts in blood molecules were also seen in the larger group.
TMU’s Prof. Rajah, a Canada Research Chair in Sex, Gender, and Diversity in Brain Health, Memory and Aging, said historically, clinical studies did not account for sex-based biological differences.
As a result, she said, little is known about how female sex and sex-specific life experiences influence Alzheimer’s disease risk and symptoms.
She said she began work in this area in 2017 because of her own curiosity about what is going on in midlife, prompting her and a collaborator to closely examine menopause.
Prof. Rajah hopes their research will help identify different risk factors for patients.
Additionally, she said, this could motivate individuals to take their health seriously in midlife through lifestyle changes such as increasing their physical activity, and encourage conversations with health care providers about possible interventions.
She also hopes more women from different backgrounds will participate in ongoing research.
“What we do as scientists is truly connected to what is in the best interest of the public and we need the support of the public to do this work.”