Women's brains appear 'years younger' than men's: study

Women tend to outlive men and stay mentally sharp longer, and a new study out Monday could explain why: female brains appear on average about three years younger.The study enrolled 121 women and 84 men, who underwent PET scans to measure brain metabolism, or the flow of oxygen and glucose in their brains.Subjects ranged from their 20s to 80s, and across those age spans, women's brains appeared metabolically younger than men's, said the findings in the Proceedings of the National Academy of Scien