A new study finds women who have both ovaries surgically removed before age 50 and carry the APOE4 gene variant face significantly higher risk of Alzheimer’s disease (AD). This research, analyzing data from over 34,000 women, found hormone therapy can reduce this risk by half, offering crucial insights into why women comprise two-thirds of Alzheimer’s cases.
By 2050, Alzheimer’s disease will affect an estimated 12.7 million people aged 65 and older. Understanding sex-specific risk factors becomes increasingly critical as women disproportionately develop the condition.
Key Takeaways
- Women with early ovary removal show four times higher odds of developing Alzheimer’s
- The APOE4 gene variant further multiplies this risk
- Hormone therapy cuts the risk by approximately half
- Education levels and body mass index influence risk factors
Published in Journal of Alzheimer’s Disease | Estimated reading time: 5 minutes
The research team, led by Dr. Gillian Einstein, Professor of Psychology and Wilfred and Joyce Posluns Chair in Women’s Brain Health and Aging at the University of Toronto, examined data from the UK Biobank. “One of our most important findings was the fact that loss of the naturally occurring hormone (endogenous), estradiol, as a result of surgical removal of both ovaries, might interact with the APOE4 allele to further increase Alzheimer’s disease risk,” explains Dr. Einstein.
The analysis revealed that women who underwent bilateral oophorectomy (removal of both ovaries) at an average age of 43 had four times higher odds of developing Alzheimer’s compared to those experiencing natural menopause around age 54. This risk increases significantly in women carrying the APOE4 gene variant.
The study also identified protective factors. Higher education levels reduced Alzheimer’s risk by 9% across all women. Surprisingly, each additional unit of body mass index lowered risk by 7% in women with early ovary removal, possibly because fat tissue produces estrone, which may help maintain cognitive function.
First author Dr. Noelia Calvo notes that hormone therapy’s effectiveness may relate to timing: “It may be due to the fact that women with ovarian removal had a loss of estradiol in their early lives when demand for this hormone may be greatest since their age of menopause was an average of 11 years earlier than those who had gone through natural menopause.”
Key Terms
- Bilateral oophorectomy
- Surgical removal of both ovaries, resulting in immediate loss of natural estrogen production and early onset of menopause.
- APOE4 allele
- A genetic variant associated with increased Alzheimer’s disease risk, particularly significant in women who undergo early ovary removal.
- Estradiol
- A naturally occurring hormone produced primarily by the ovaries, playing crucial roles in cognitive function and brain health.
Test Your Knowledge
How does early ovary removal affect Alzheimer’s risk?
Women who have both ovaries removed around age 43 show four times higher odds of developing Alzheimer’s compared to those experiencing natural menopause at 54.
What methods did researchers use to conduct this study?
Researchers analyzed data from 34,603 women in the UK Biobank, comparing Alzheimer’s disease rates between those with early ovary removal and natural menopause while accounting for various health and demographic factors.
How does hormone therapy affect Alzheimer’s risk in women with early ovary removal?
Women who underwent early ovary removal and took hormone therapy showed less than half the odds of developing Alzheimer’s compared to those who didn’t take hormone therapy.
What protective factors did the study identify?
Higher education levels reduced risk by 9% for all women, while higher body mass index provided unexpected protection for women with early ovary removal, potentially due to fat tissue’s role in hormone production.
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