Severe mental illness is falling in American’s children, a surprising new study has found. Researchers analyzed 54,000 children aged 6 to 17 by asking parents how much of a problem their children have with things like “feeling unhappy or sad” or “getting along with other kids.” Children with high scores on this so-called impairment scale are defined as severely impaired. There has been a 16 percent decrease in severely impaired children from 1996 to 2012. “The finding is robust and real and challenges the prevailing stereotype that young people are somehow more vulnerable to mental problems,” said lead author Mark Olfson of Columbia University. By contrast, government surveys have shown increasing prevalence of disorders like ADD and autism. Olfson said the study didn't investigate why mental illness has apparently fallen so dramatically.