MRI scans of patients show patients with Alzheimer’s disease. (Credit: Atthapon Raksthaput/Shutterstock)

Scientists are still unraveling why Alzheimer’s disease affects men and women disproportionately. Out of the five million Americans who have it, about 64 percent are women.

Once in their 60s, women are twice as likely to develop Alzheimer’s than breast cancer, and more than twice as likely to develop Alzheimer’s as their male counterparts. And when women develop the disease, the effect