Narrator: This is Science Today. Psychologist Lillian Cartwright of the University of California, San Francisco has been studying a group of high-achieving professional women for 30 years, since they entered medical school. At that time, they were the cream of the crop intellectually and physically.

Cartwright: What they were as a group was extremely intelligent and very very healthy. And what we found when they're in their mid-40s is that a third of the group are not in good health.

Narrator: Cartwright discovered the unhealthy women had several traits in common.

Cartwright: We found that class background of parents was a significant predictor. So that those women that came from backgrounds where neither father nor mother were college educated were more likely to be in poor health at midlife.

Narrator: Another, surprising finding was that women who in their twenties were more organized and efficient with their time were healthier in middle age. Plus, the healthy women exercise a lot more. Cartwright thinks that means they simply take better care of themselves in general. For Science Today, I'm Steve Tokar.