Stories like Gemma’s suggest that when it comes to depression, adolescents are not easy to treat. It’s not always apparent where normal adolescence ends and mental illness begins–even healthy teenagers tend to be impatient, insecure and overly emotional. Symptoms of teen depression–oversleeping, overeating, irritability, oversensitivity–can often be mistaken for typical adolescent moodiness. With little data available, doctors have been left to their instincts. What few studies have been done have tended to stoke, rather than resolve, the debate over drugs versus talk therapy.

A new study, though, has tipped the scale toward drugs as the most effective therapy. Last week the U.S. National Institute of Mental Health released preliminary results of a decadelong survey of nearly 400 children from across the country. Researchers divided the children into four groups–those treated with Prozac, cognitive behavioral therapy (CBT), a combination of the two and a placebo–and compared the results. The best treatment turned out to be a combination of drugs and therapy, followed by Prozac alone. CBT by itself–the most effective treatment for adults–rated hardly better than the placebo. “Surprisingly for all of us, the results are very different from the results we’ve seen in adults,” says Dr. Harold S. Koplewicz, director of the Child Study Center at New York University.

That would tend to vindicate doctors across Europe and the United States, who have prescribed copious antidepressants to kids in recent years. According to the U.K. government’s drug watchdog, prescriptions for schoolkids 16 to 18 trebled from 46,000 in 1995 to 140,000 last year. In the United States, prescriptions to under-18s increased 49 percent between 1998 and 2002, according to a study in the April issue of the journal Psychiatric Services. Even Koplewicz–who argues in “More than Moody: Recognizing and Treating Adolescent Depression” that CBT should be the first line of attack–now admits that the recent study is the “gold standard.” “The best news a parent can get is for a mental-health professional to say this is just adolescence,” he says. “And if it isn’t, the good news is we’ve found an effective way to treat it.”

Not everybody, though, is sure. Dr. David Healy of the University of Wales says the study’s methodology hasn’t yet been published or peer reviewed. The results might turn out differently, argues University of Pittsburgh psychiatrist David Brent, if another form of therapy were used. Because CBT requires that patients perform homework and exercises, some therapists argue that they aren’t well suited to children, who tend to be impatient with such tasks.

Drugs also aren’t risk-free. Last year Britain banned the use of all antidepressants except Prozac for adolescents after British researchers noted a higher suicide rate among depressed teens taking them. An article in April’s issue of The Lancet, a medical journal, advised against young patients’ taking four popular antidepressants because of an increased risk of suicidal behavior. The matter won’t be resolved without further study of the effect of both drugs and therapy. One thing, though, is clear: teens should be handled with care.