Male depression
An intervention may be the best way to prevent the onset of depression in adolescentsFlickr

A low-cost, one-time intervention that educates teenagers about the changeable nature of personality traits may prevent an increase in depressive symptoms often seen during adolescence, according to new research.

The findings, published in the journal Clinical Psychological Science, are important as few interventions have successfully staved off the onset of depressive symptoms among teenagers.

Lead researcher David Scott Yeager, of the University of Texas at Austin, said: "We were amazed that a brief exposure to the message that people can change, during a key transition — the first few weeks of high school — could prevent increases in symptoms of depression."

"It doesn't come close to solving the whole problem," Yeager explained. "Yet finding anything promising has the potential to be important because prevention is far better than treatment — not only for financial reasons but also because it avoids human suffering."

In 2012, an estimated 2.2 million children in the US aged between 12 to 17 had at least one major depressive episode in the past year, according to the National Institutes of Health.

Research suggests many lifelong cases of major depression emerge during adolescence, which occur during the transitional period marked by puberty and also changes in friendship networks and positions of status.

Yeager questioned whether debunking the belief that social adversities are unchangeable might ward off feelings of despair that can bloom into depression.

"When teens are excluded or bullied, it can be reasonable to wonder if they are 'losers' or 'not likable,'" he said. "We asked: Could teaching teens that people can change reduce those thoughts? And if so could it even prevent overall symptoms of depression?"

For the study, researchers conducted an intervention study with around 600 14 and 15 year olds across three different high schools.

At the beginning of the school year, students were randomly assigned to participate in the treatment intervention or a similar control activity, though they were not aware of the group assignment.

Students assigned to the treatment intervention read a passage describing how individuals' personalities are subject to change. The passage emphasised that being bullied is not the result of a fixed, personal deficiency, nor are bullies essentially "bad" people. An article about brain plasticity and endorsements from older students accompanied the passage.

After reading the materials, the students were asked to write their own narrative about how personalities can change, to be shared with future students.

Students in the control group read a passage that focused on the malleability of a trait not related to personality: athletic ability.

Nine months later, rates of clinically significant depressive symptoms rose by roughly 39% among students in the control group, in line with previous research on depression in adolescence.

Students who learned about the malleability of personality, on the other hand, showed no such increase in depressive symptoms, even if they were bullied.

Yeager said the results were promising but there were limitations. "For example, will this intervention work equally well for all students?" he asked. "What symptoms are most affected or least affected? We don't have good answers to these questions yet."