Two-thirds of Alzheimer’s cases in the United States are in women. Researchers used to think that more women got Alzheimer’s because they lived longer. But now, studies are showing there may be other factors at play.

By age 65, 1 in 5 women will develop Alzheimer’s.

“I forgot so many words in one sentence that I couldn’t have a conversation,” said Virginia Sams.

But why does Alzheimer’s affect more women than men? One study found menopause, which reduces estrogen levels in a women’s body, may be to blame. Scientists scanned the brains of women and men and found declines in estrogen were involved in Alzheimer’s abnormalities.

Another recent report found women with more belly fat had a higher risk for dementia than men with the same issue. Specifically, women with a higher waist circumference had a 39% increased risk of dementia in 15 years.

And researchers recently performed brain scans on more than 1,000 older adults and found women metabolized sugar better, which may help them compensate for dementia damage better causing a delayed diagnosis. In the future, earlier diagnosis may mean better treatment and outcomes.

Researchers at the University of Miami recently analyzed genes in 30,000 people—half with Alzheimer’s and half without. They found four genes seem to be related to the disease by sex. Specifically, one of the genes was linked to Alzheimer’s risk in women and three were linked to risk in men.