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(THE CONVERSATION) Around 2012, something started going wrong in the lives of teens.

In just the five years between 2010 and 2015, the number of U.S. teens who felt useless and joyless – classic symptoms of depression – surged 33 percent in large national surveys. Teen suicide attempts increased 23 percent. Even more troubling, the number of 13- to 18-year-olds who committed suicide jumped 31 percent.

In a new paper published in Clinical Psychological Science, my colleagues and I f...