Doctors have long known that children prescribed antipsychotic medications are at risk for weight gain. A new study shows just how big the problem really is. Business reporter Duff Wilson reports:Children and adolescents who take the newest generation of antipsychotic medications risk rapid weight gain and metabolic changes that could lead to diabetes, hypertension and other illnesses, according to the biggest study yet of first-time users of the drugs.The study, to be published Wednesday in The