DMDD officially appeared as a diagnosable condition in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) in 2013. Prior to this recognition, "children were being diagnosed prematurely with bipolar disorder, but as they developed, they would not actually have bipolar disorder," according to Matis Miller, a licensed clinical social worker in Lakewood, New Jersey, the founder and director of The Center for Cognitive and Behavioral Therapy and the author of The Uncontrollable Child . DMDD "includes frequent and chronic moodiness [and] a lot of irritability," says Boston-based clinical psychologist Alisha Pollastri, Ph.D., principal investigator of the Laboratory of Youth Behavior. But the symptoms go beyond the typical tantrum. "They are much more severe, much more frequent and inconsistent with the child's developmental level," she says. For example, there may be a 10-year-old having tantrums that look like something you would expect ...