When Anya Bailey developed an eating disorder after her 12th birthday, her mother took her to a psychiatrist at the University of Minnesota who prescribed a powerful antipsychotic drug called Risperdal. Created for schizophrenia, Risperdal is not approved to treat eating disorders, but increased appetite is a common side effect and doctors may prescribe drugs as they see fit. Anya gained weight but within two years developed a crippling knot in her back. She now receives regular injections of Botox to unclench her back muscles. She often awakens crying in pain. Isabella Bailey, Anya's mother, said she had no idea that children might be especially susceptible to Risperdal's side effects. Nor did she know that Risperdal and similar medicines were not approved at the time to treat children. Just as surprising, Ms. Bailey said, was learning that the university psychiatrist who supervised Anya's care received more than $7,000 from 2003 to 2004 from Johnson & Johnson, Risperdal's maker, in return for lectures about one of the company's drugs. The intersection of money and medicine, and its effect on the well-being of patients, has become one of the most contentious issues in health care. Nowhere is that more true than in psychiatry, where increasing payments to doctors have coincided with the growing use in children of a relatively new class of drugs known as atypical antipsychotics. These best-selling drugs, including Risperdal, Seroquel, Zyprexa, Abilify and Geodon, are now being prescribed to more than half a million children in the United States to help parents deal with behavior problems despite profound risks and almost no approved uses for minors.