In the United States, women make up two-thirds of people with Alzheimer’s disease, and recent studies show this prevalence may be associated with the amount of estrogen and progesterone in their bodies. Reported at the Alzheimer’s Association International Conference in Chicago, Illinois, women who have three or more children have a 12% lower risk of developing dementia than women who have only one child. Also, women who experience menopause at 45 or younger have a 28% higher risk than women who go through menopause later in life. Furthermore, women who begin menstruation earlier are also less likely to develop dementia, as reported by NPR. But researchers are not sure whether it’s the presence of the hormones that affects women’s risk, or whether it’s the constant changes in hormone levels that women experience throughout life.