Major depression is one of the most common mental-health problems in adolescence with rates of around 5.9% among girls and 4.6% among boys. It is associated with functional impairment, risk of suicide and a risk of depression in adulthood. A team of researchers from Duke University in North Carolina looked into the long-term outcomes of 196 adolescents, aged between 14 and 22, who had originally participated in a study into the effectiveness of different kinds of treatment for depression. The researchers found that 96.4% of the participants had recovered by the time they were followed up five years after the original study. Recovery by two years was more likely in participants who responded quickly to treatment (96.2%) than for those who responded only partially or not at all (79.1%). Of the 189 participants who recovered 46.6% had a recurrence. Girls (57%) were more likely than boys (32.9%) to have a relapse.
Curry, John ... [et al] - Recovery and recurrence following treatment for adolescent major depression Archives of General Psychiatry 2011; 68(3):263-270.