According to the National Institute of Mental Health, half of all cases of mental illness start by age 14, and about 11% of adolescents have a depressive disorder by age 18.

WSJ: Will Students Take a Mental Health Test?

Institute researchers looked at database of five billion mental health claims between 2007 and 2011 from people under age 65 with employer-based benefits administered by Humana (HUM), UnitedHealth Group (UNH), Aetna (AET) and Kaiser Permanente.

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