Experts once believed that women’s longer life span explained why they were more likely than men to be stricken with Alzheimer’s disease. But according to new findings presented at the Alzheimer’s Association International Conference, many biological and social differences between the sexes influence a woman’s risk of developing the neurodegenerative disease, reports CNN.

According to the World Health Organization, 50 million people around the globe are living with dementia and Alzheimer’s. Most of them are women. What’s more, two thirds of the 5.7 million Americans living with Alzheimer’s are female.

Several studies at the conference examined how pregnancy, female hormones, age at first menstruation, menopause and a woman’s innate cognitive advantages affect their risk and treatment for the progressive illness.

A study by Kaiser Permanente found an association between a lower risk for dementia and the number of births a woman experiences. For example, women with three or more children had a 12 percent lower risk of developing cognitive issues compared with those who had only one child.

Researchers also found that women with multiple failed pregnancies (for example, several miscarriages), those who began their period later in life (at age 16 or older) or were fertile for only 21 to 30 years faced a greater risk of dementia.

Another study hinted at the necessity for more accurate screening tests for Alzheimer’s after findings showed that current cognitive tests rely heavily on verbal memory, which is better in women compared with men. This means that women with mild cognitive decline may nonetheless score as normal on a test, which might prevent them from starting drug treatment for Alzheimer’s and making necessary lifestyle adjustments.

Conversely, men could score a false positive on the same test and be diagnosed with changes in the brain when, in fact, they’re normal.

Additionally, Carey Gleason, PhD, MS, of the Wisconsin Alzheimer’s Disease Research Center, and colleagues found that hormone replacement therapy (HRT) affected cognitive function. The researchers discovered that women who begin HRT in their 70s are more likely to experience mild cognitive impairment. However, younger women who start HRT within a few years of menopause are only at an increased risk for dementia if they have type 2 diabetes.

“We’re at a very exciting time in the field,” said Rachel Whitmer, PhD, professor of public health sciences at the UC Davis School of Medicine. “Rather than brushing it aside as ‘women live longer and that’s the end of story,’ science is now breaking it down to a deeper level to understand the where, when, why and how.”

Click here to learn about why African Americans suffer higher rates of Alzheimer’s.