NEW YORK (Reuters Health) - A majority of teenagers treated for major depression show lasting improvements, though it may take several months for the benefits to appear, a new study suggests.

The study of 439 teenagers with major depression found that while only about one-quarter saw their symptoms go into remission after the first 12 weeks of therapy, that rate improved to 60 percent by the 9-month mark.

When it came to long-term recovery, the researchers found that of teenagers who did respond to therapy early on, two-thirds maintained the improvements over 9 months. The same was true of 71 percent of teens who initially took longer than 12 weeks to respond to therapy.

The findings highlight the importance of not giving up on depression treatment, as remission rates get better over time, the researchers report in the Journal of the American Academy of Child and Adolescent Psychiatry.

The study also suggests that cognitive-behavioral therapy (CBT) and antidepressant drugs are similarly effective over the long term, according to the investigators, led by Dr. Betsy D. Kennard of the University of Texas Southwestern Medical Center at Dallas.

However, teenagers who received both therapies were more likely to show quick improvements than those on either treatment alone, the study found.

That means that choosing just one therapy might delay many teenagers' recovery by 2 or 3 months, Kennard and her colleagues write.

They also point out that despite the positive finding that a majority of teenagers got better, a substantial number were still clinically depressed after 9 months of treatment.

More research, they say, is needed to understand how to best help these teenagers -- and to see whether recovery can come more quickly for others. It will also be important, the researchers say, to understand why some teenagers who initially improve see their depression symptoms return.

The study was funded by the National Institute of Mental Health. Several researchers on the work have received funds from drug companies that market antidepressants.

SOURCE: Journal of the American Academy of Child and Adolescent Psychiatry, February 2009.

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