Foster children are being prescribed cocktails of powerful antipsychosis drugs just as frequently as some of the most mentally disabled youngsters on Medicaid, a new study suggests.

The report, published Monday in the journal Pediatrics, is the first to investigate how often youngsters in foster care are given two antipsychotic drugs at once, the authors said. The drugs include Risperdal, Seroquel and Zyprexa — among other so-called major tranquilizers — which were developed for schizophrenia but are now used as all-purpose drugs for almost any psychiatric symptoms.

“The kids in foster care may come from bad homes, but they do not have the sort of complex medical issues that those in the disabled population do,” said Susan dosReis, an associate professor in the University of Maryland School of Pharmacy and the lead author.

The implication, Dr. dosReis and other experts said: Doctors are treating foster children’s behavioral problems with the same powerful drugs given to people with schizophrenia and severe bipolar disorder. “We simply don’t have evidence to support this kind of use, especially in young children,” Dr. dosReis said.