Promising new drugs to treat schizophrenia, depression and other severe mental illnesses typically cost twice as much in the United States as they do in the rest of North America and in Europe, according to a study released Wednesday.

The U.S. price was higher for each of eight drugs sampled - more than six times higher in one case. And while the study focused on antidepressants and antipsychotics, its authors say the disparity in prices likely is as stark for antibiotics, heart drugs and other medications."There are thousands of people, if not tens of thousands, for whom the impact of this price gouging is that they don't get treated," said Dr. Sidney M. Wolfe, director of Public Citizen's Health Research Group, a Washington nonprofit that conducted the study.

But Alan F. Holmer, president of the Pharmaceutical Research and Manufacturers Association of America, said that "our companies take on the extraordinary risk of drug discovery because the American free-market system offers incentives and potential rewards. In other countries around the world, especially Europe, when the free market is stifled by price controls or patent piracy, the lights in the laboratories go out."

The Public Citizen study was prompted by anecdotal reports of big gaps in drug prices between Europe and America, said Dr. E. Fuller Torrey, a psychiatrist and one of the authors. The reports dealt with the new generation of drugs to treat mental illness.

Five antidepressants and three antipsychotic drugs were selected for the survey, and the costs to pharmacists in the United States, Canada, Mexico and 14 European countries were compared. The findings were dramatic: For most drugs in most countries there was a relatively narrow cost difference. The big exception was the United States.

Why the huge differences? All other countries have national health insurance, which gives them clout in negotiations with big pharmaceutical companies, the study authors say.