That question is hotly debated in scientific journals, but it isn't just academic. It also cuts to the core of public welfare by making it possible for financial profit to affect decisions about who needs treatment, whether they are prescribed medicine and which ones, says Lisa Cosgrove, a psychologist at the University of Massachusetts-Boston.

Critics such as Cosgrove say there's a damaging conflict of interest in the financial ties between drug companies and leaders who are revising the "bible" of psychiatric diagnoses, the Diagnostic and Statistical Manual of Mental Disorders (DSM-V), as well as guidelines on the best treatments.

About 160 experts appointed by the American Psychiatric Association are doing the heavy lifting on the updated manual, expected in 2012. They're tops in their field, and because industry pays for two-thirds of research, many of them consult for drug companies or do corporate-funded studies, says Darrel Regier, research director for the group. "There's this assumption that a tie with a company is evidence for bias. But these people can be objective," he says.

This is the first time the psychiatry association has required members of 13 working groups on diagnoses, as well as the leadership task force, to publicly disclose all industry ties.

Sixty-eight percent of task-force members report economic ties with drug companies, Cosgrove says. And of those with links, about four out of five don't just get research funding, they're on corporate boards, hold stock or collect money as advisers, she says. She and Harvard Medical School psychiatrist Harold Bursztajn have criticized these ties in The New England Journal of Medicine and Psychiatric Times.

Even small changes in the symptoms for diagnosis of a problem can greatly increase prescriptions for drugs, Cosgrove says, so anyone who could benefit from changes has a potential conflict.

More than half of the members on the 13 working groups also have such ties, according to Cosgrove's analysis. She says no group should have a majority with drug company links.

But Regier argues: "We want the best people. We don't want quotas or an artificial litmus test." He says potential conflicts are limited by a rule that panel members can't receive more than $10,000 from drug companies while at work on the new DSM.

The $10,000 limit "is not a particularly sensible idea," says Daniel Carlat, a Tufts psychiatrist who publishes an independent monthly, The Carlat Psychiatry Report, on trends in the field. "They've had lucrative relationships in the past, and they know they're going right back to them."

Carlat says it's unrealistic to exclude people with industry-research funding, but he favors limits on those who give promotional talks on drugs, "the real hired guns," and others with a direct financial interest in firms. "Maybe no more than 30%, maybe no more than 50%. These panels shouldn't be stacked the way they are now," he says.

Another flash point: clinical guidelines. Cosgrove led a study on 20 authors of treatment standards for major depression, bipolar disorder and schizophrenia: 90% of them had financial ties to firms that make drugs recommended for the disorder.

But the psychiatry group casts a net to hundreds of reviewers for every guideline, says John McIntyre, who chairs the guidelines committee. The depression and bipolar standards are being updated, "and we've gotten thousands of comments online," Regier says. So any bias gets diluted by diverse voices, McIntyre says; plus, the guidelines are based on evidence.

But there's the rub, critics say, because drug company-funded studies consistently come out with more positive results for their drug than do independent studies.

"In psychiatry, many diseases are treated equally well with medication or therapy," Carlat says. "But the guidelines tend to be biased toward medication" because it's costly to make and study drugs.

Much is at stake. Antipsychotics, which had $14.6 billion in sales last year, were the top-selling class of U.S. medicines; antidepressants brought in $9.6 billion, says IMS HEALTH.

The debate over whether economic self-interest may bias the DSM and treatment guidelines leads to a root issue: Drug companies pay for gathering evidence, and there's no major alternative on the horizon, says Paul Appelbaum, an expert on ethics in psychiatry at Columbia University. He's concerned about potential conflicts. But other financing suggestions — for example, companies contributing money for studies run independently by the government — have gone nowhere, he says.

"We're a capitalist society built on competition, and that has led to many successes," Appelbaum says. "But this conflict-of-interest issue shows the side effects of the system we have."