Nick, now 14, had always been easygoing and upbeat. But when his studies started slipping and his moods grew erratic, his parents became concerned. He admitted he "was feeling kind of yucky," though he couldn't pinpoint the cause. Now, with the help of a mental health professional, Nick is slowly emerging from what turned out to be an episode of clinical depression.

Once thought to be rare or virtually non-existent, depression in young people is now recognized as a serious medical problem that can adversely affect nearly all aspects of a youngster’s life.

"As many as to 2.5 percent of children and 5 percent of adolescents are estimated to have major depressive disorder," says John F. Curry, PhD, of Duke’s Child and Family Study Center. “It’s a quiet kind of problem, unlike hyperactivity. So, all too often, nobody notices.”

In childhood, depression affects boys and girls equally. By adolescence, however, depression occurs in the same 2:1 female-to-male ratio found in adults. “This change comes around age 14,” says Curry, adding that the reasons for this disparity are under study. “It may reflect increased social pressure on girls, body image concerns, or hormonal influences.”

While young children are more likely to present with obvious sadness, says Curry, depression in teens can be trickier to diagnose, as even teens without serious affective disorders are often on an emotional roller coaster and behave erratically from time to time.

The first symptoms that your teen may be struggling with clinical depression could include trouble concentrating in school, weight change (loss or gain), or excessive sleep. Persistent irritability, anger, or boredom are other danger signs.

Because depressed teens are more likely than depressed children to have suicidal thoughts or behavior, such symptoms should be taken seriously: Suicide is the third leading cause of death in American adolescents.

Treatment for Adolescents with Depression Study

Duke is the coordinating center for TADS (Treatment for Adolescents with Depression), a major 12-site study funded by the National Institute of Mental Health that examined the best way to treat depression in teenagers.

More than 400 teens were randomly assigned to one of four treatments: fluoxetine (Prozac), cognitive behavioral therapy, a combination of fluoxetine and cognitive behavioral therapy, or placebo. At the end of 12 weeks of treatment the combination of fluoxetine and cognitive behavior therapy led to the greatest reductions in depression and in suicidal thinking. Fluoxetine alone also reduced depression significantly more than the placebo.

Teens may also gain a mood boost through physical activity, says Duke clinical psychologist Scott Compton, who is exploring whether exercise can be an effective treatment for adolescents with depression.

"We know that exercise can be an effective treatment for older adults with depression," Compton notes. "In our pilot study, most of the teenagers reported significant benefits, and we'd like to expand the research further."

The main take-home: It isn’t always easy, but do your best to keep the lines of communication with your teen open -- and be vigilant for signs of serious depression. “Make sure your child's doctor knows about sad feelings, loss of interest in things that used to be fun, change in appetite, and trouble getting or staying asleep," Curry says. "There is help available, but diagnosis is the essential first step."