EARLIER this summer, the American Psychiatric Association announced that a 27-member panel will update its official diagnostic handbook, the Diagnostic and Statistical Manual of Mental Disorders. The fifth edition, which is scheduled to come out in 2012, is likely to add new mental illnesses and refine some existing ones. High on the agenda will be the controversial diagnosis of childhood bipolar disorder. Recent data show that office visits by children and adolescents treated for the condition jumped 40-fold from 1994 to 2003. We still don’t know how much of this increase represents long-overdue care of mentally ill youth and how...