Dr. Stixrud: We know that there's a genetic component to depression, although genes contribute much less to depression than to other disorders such as autism and ADHD. The genetic contribution to depression is on the order of 35-50 percent, which means that most of the contribution doesn't come from genetics. It comes from your experience, and the primary culprit is stress.

Dr. Stixrud: One of the world's top experts on child and adolescent mental health says that the highest political priority in this country should be preventing mental health problems in children and adolescents. By preventing these problems in childhood and adolescence, we could then prevent most adult mental health problems, for which we pay an enormous price in terms of human suffering and health care costs as well.

Dr. Stixrud: Yes, and I'm not the only one. A top expert on childhood brain development and mental health problems once advised one of my young patients, who wanted to go off medicine for depression, in this way, "You've got my blessing, as long as you do three things: you keep a regular schedule; you get plenty of sleep; and you learn to meditate." He said that because he's worked at the National Institutes of Health, where researchers were studying the connection between stress and depression. He knew that when people get depressed, their stress hormones get imbalanced. This can be prevented by normalizing the stress response. Practicing the Transcendental Meditation technique twice a day helps young people build an orderliness, a structure and a routine into their day, which allows the nervous system to function better.

Dr. Stixrud: Yes, and one of the really worrisome things about depression is how much of it there is in young people. There's not complete agreement, but many professionals in this area think that we're seeing an epidemic of depression. Virtually everybody agrees that the onset of depression is much younger, so that a generation or two ago, the average age of onset of depression was 34 or 35. Now, it's 14.

Researchers say that depression scars the brain, so that even if teenagers are treated for depression and it lifts, they're more pessimistic than they were before. They have more trouble sleeping than they had before, which places them at risk for getting depressed again. And every time a person gets depressed, it makes it more likely that he or she will have a lifetime of depression, which is why experts say that the highest priority should be preventing mental health problems in adolescents.

Dr. Stixrud: I saw a boy with ADHD when he was 10, and he was very hyperactive, but also irrepressible, delightful, extremely funny, extremely smart, and an enormously likeable boy. I saw him again when he was 16, and he was on anti-depressants. I said, "So, what's the story with the Zoloft?" And he said, "Well, they used to call me the Teflon Kid, because when I was younger everything just rolled off my back. I was always in a good mood. But then I hit high school, and I wasn't getting enough sleep. I really wanted to go to Duke, and I started staying up until 1:00 a.m. every night trying to do as well as I could in school. And I got worn out. I just got depressed."

And I think that this happens over and over and over again, particularly with girls, because once they hit adolescence, girls are at much higher risk for depression than boys are. I do a lot of consulting with private girls' schools, many of which are very academically demanding. I'm trying to help them understand that in the long run, we don't want these teenagers to be so tired and so stressed that they get depressed. At Harvard, for example, 80% of the student respondents to a newspaper survey said that they had felt depressed in the last year.

Dr. Stixrud: I feel that teaching kids to practice the Transcendental Meditation program is arguably the best thing we could possibly do for them. I say this because it can help them to create environments that are relatively de-stressed, to normalize their own stress response, to build order and regularity into their routines, and to experience a deep level of happiness, creativity, and energy.