A team of researchers at the University of Toronto have found that women who had their ovaries removed in their 30s and 40s to protect against a genetic predisposition to certain forms of cancer are nearly two times more likely to experience memory issues—or what scientists call subjective cognitive decline (SCD).
Defined as an individual’s reports of worsening or more frequent memory loss, SCD is considered an early indicator of Alzheimer’s disease.
“While a bilateral salpingo-oophorectomy (BSO) is performed primarily as a preventive measure for serious health concerns, including cancer, its effects on cognitive health have remained understudied, particularly in younger middle-aged women,” says Gillian Einstein, Wilfred and Joyce Posluns Chair in Women's Brain Health and Aging and professor of psychology in the Faculty of Arts and Science. “Because these women have almost twice the likelihood of later life Alzheimer disease, it is critical to understand these earliest brain changes.”
Their work suggests that interventions at the earliest signs of cognitive changes can boost women’s resilience against some of the negative impacts associated with the procedure.
“BSOs lead to the loss of a key estrogen, 17-b-estradiol, which is one factor we have found to be associated with increased risk of subjective cognitive decline,” says Noelia Calvo, a Research Associate in the Department of Psychology and first author on the paper that discusses their study.
Their findings are detailed in “Cognitive and brain health in women with early bilateral salpingo-oophorectomy: Implications for risk, resilience and subjective cognitive decline,” which was published in the journal of the Alzheimer’s Association, Alzheimer’s and Dementia. Calvo and Einstein worked alongside researchers in the Department of Psychology and the Faculty of Medicine.
Their previous research linked early-life BSO to a fourfold increase in the risk of late-life Alzheimer’s disease, particularly in women who carry the APOE4 gene (a known risk factor) in a large British cohort. The current study is the first to involve early middle-age Canadian women in an analysis of factors contributing to both risk and resilience within five years of BSO.
This study involved 333 Canadian women who have had BSO and who have not. Among those who have, some also experience SCD.
Using Magnetic Resonance Imaging (MRI), the researchers found that women who had BSO and experience SCD have decreased brain grey matter, particularly in regions sensitive to the hormone estradiol and in regions important for mood, memory, and language.
“While SCD does not meet the diagnostic criteria for dementia, understanding its cognitive and structural brain changes may help refine early diagnostic markers that are sex-specific,” says Calvo. “This study highlights the importance of intervening at the earliest stages of cognitive and brain changes in younger women.”
For women taking estradiol therapy after BSO, the risk of cognitive decline in the first five years appeared to be significantly reduced.
The need for early interventions is clear: Approximately 750,000 Canadians live with Alzheimer’s disease or another form of dementia, three quarters of which are women. In 2022, Alzheimer’s disease was the ninth leading cause of all deaths in Canada.
Calvo and Einstein emphasize that further research is needed to better understand how early life hormonal changes, particularly estradiol loss, affect women’s brains throughout each stage of their lives.
Funding
This work was supported by the Wilfred and Joyce Posluns Chair in Women’s Brain Health and Aging from the Posluns Family Foundation; the Canadian Institutes of Health Research (CIHR); the Ontario Brain Institute and The Centre for Aging + Brain Health Innovation (CABHI); the Canadian Cancer Society; the Canadian Consortium on Neurodegeneration in Aging (CCNA); and the Jacqueline Ford Gender and Health Fund.
More Information
To learn more about this study or to speak to its authors, please contact:
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Michael Pereira
Communications Officer, Department of Psychology, University of Toronto
psy.communications.officer@utoronto.ca