EMBARGOED FOR RELEASE UNTIL 4 PM ET, November 03, 2021
Does Estrogen Protect Against the Risk of Brain Shrinkage?
MINNEAPOLIS -A new study found that people with higher cumulative estrogen exposure over their lifetime had greater brain volumes and fewer indicators of brain disease on their brain scans in midlife . The research is published in the November 3, 2021, online issue of , the medical journal of the 好色先生. 鈥淲e found that a number of ways a woman is exposed to estrogen鈥攏ot having reached menopause, having more total reproductive years, having a higher number of children, using menopause hormone therapy or hormonal contraceptives鈥攚ere associated with larger gray matter volumes in midlife,鈥 said author Lisa Mosconi, PhD, of Weill Cornell Medicine in New York, N.Y. The study looked at 99 women between the ages of 40 and 65 who did not have dementia. They did have risk factors for late-onset Alzheimer鈥檚, such as family history of the disease or the APOE gene that is linked to a greater risk. Researchers compared them to 29 men, matched for age, with similar risk factors. Then researchers looked at the association of reproductive history with the volume of gray matter in the brain, which is an indicator of brain health, and scores on thinking and memory tests. When looking at people鈥檚 brain scans, several events that indicate longer estrogen exposure, like more than 39 reproductive years, a higher number of children and pregnancies, and use of hormone replacement therapy and/or hormone contraceptives, were associated with greater gray matter volume. This appeared mainly in the temporal cortex, frontal cortex, and precuneus, areas of the brain in which Alzheimer鈥檚 biomarkers often show up first. The results were the same after adjusting for factors like high blood pressure and smoking. For example, for every year longer that a woman was exposed to estrogen in her life, average gray matter volume in certain areas of the brain increased by an average of 1%. People with total reproductive years of 39 years or longer had gray matter volume an average of 5% larger than people with total reproductive years of less than 39 years. Total reproductive years is the difference between the age at menopause and the age when a woman鈥檚 period begins. For each additional child a woman had, gray matter volume in certain areas of the brain increased by an average of 2%. When researchers looked at people鈥檚 scores on tests of thinking and memory, they found no association with reproductive history indicators. However, people鈥檚 gray matter volume in the temporal regions of the brain was associated with better scores. 鈥淧revious research has shown that the midlife decline in estrogen that comes with menopause is a driver of brain aging and Alzheimer鈥檚 risk in women,鈥 Mosconi said. 鈥淥ur results confirm that, but there鈥檚 also good news. Other factors related to women鈥檚 reproductive history, such as a longer reproductive span and use of hormonal therapy, appear to offset the effects of menopause. While the age at which menopause starts is determined partly by a person鈥檚 genetics, lifestyle and environmental factors like smoking, obesity and exercise also play a role, and may modify a woman鈥檚 risk of brain aging.鈥 The study does not prove that estrogen reduces dementia risk, it only shows an association between the two. A limitation of the study is that brain scans showing gray matter volume may indicate other types of brain disease, not just the kind related to Alzheimer鈥檚. The study was supported by the National Institutes for Health, National Institute on Aging, the Cure Alzheimer鈥檚 Fund, Maria Shriver鈥檚 Women鈥檚 Alzheimer鈥檚 Movement, and Harold W. McGraw III and Nancy McGraw, and Carol and Michael Weisman. Learn more about Alzheimer鈥檚 disease at , home of the 好色先生鈥檚 free patient and caregiver magazine focused on the intersection of neurologic disease and brain health. Follow Brain & Life庐 on , and . When posting to social media channels about this research, we encourage you to use the hashtags #Neurology and #AANscience.