Estrogen is a steroid hormone linked to the female reproductive organs and is responsible for developing female sexual characteristics.
In a study from Alzheimer’s Research UK, scientists found an association between indicators of longer estrogen exposure and reduced brain shrinkage in midlife women.
Previous research into the effects of estrogen on brain health has shown mixed results.
Some studies suggested that lower estrogen levels following menopause could be linked to brain aging and Alzheimer’s risk later in life.
In the study, researchers looked at a total of 128 volunteers (99 women and 29 men), aged between 40 and 65 all with risk factors for Alzheimer’s disease, such as the APOE4 risk gene or a family history of the disease.
A range of reproductive history events was examined by questionnaires and interviews. These events included:
- Whether participants had experienced menopause or a hysterectomy
- The age they started periods
- Their age at menopause
- The length of time between the start of their periods and the start of menopause
- The number of children and pregnancies they may have had
- Whether they use menopausal hormone therapy (HT) and hormonal contraceptives (HC).
The researchers used brain scans to look specifically at areas called gray matter, including key regions that are damaged in Alzheimer’s disease.
Lower volumes of gray matter have been linked to dementia risk and poorer brain health. All participants also had memory tests to assess their thinking and language skills.
The team found exposure to estrogen as a result of not having reached menopause, having more children and more reproductive years, and using HT and HC, was linked to larger gray matter volumes in midlife women.
They found no association between reproductive history events and people’s memory scores, but people who scored better did have more gray matter compared to those that scored less.
The team says two-thirds of people with dementia are women and while some of this difference is explained by women living longer, research has also implicated hormones like estrogen.
This study linked exposure to estrogen to less brain shrinkage, an indication of lower dementia risk, but this is a small study, and it did not explain the causes for the association.
Examining the biological pathways through which reproductive history influences cognitive aging and Alzheimer’s disease risk is the next step for researchers to understand this link.
If you care about brain health, please read studies about how the Mediterranean diet could protect your brain health, and Vitamin B supplements could help reduce dementia risk.
For more information about brain health, please see recent studies about antioxidants that could help reduce dementia risk, and Vitamin D deficiency linked to higher dementia risk.
The study was conducted by Dr. Sara Imarisio et al and published in Neurology.
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