BOSTON (Boston Globe) — A day after Michael McDermott's parents revealed that their son had been hospitalized for depression and was being treated for it when he allegedly gunned down seven co-workers, psychiatrists said people suffering from the disorder are no more prone to violence than the general population.

Some mental illnesses, such as schizophrenia and bipolar disorder, may be associated with a slightly increased risk of violence, which grows significantly if the sufferer also abuses drugs or alcohol. But even those risks are greatly exaggerated by popular culture, the experts said.

Among mental illnesses, depression is one of the least associated with violence towards others, though sufferers are at increased risk of harming themselves, psychiatrists said. People who suffer depression at some point in their lives make up between 6 and 20 percent of the population.

"I would hate to think that now people in the workplace were looking over their shoulder worrying that if someone had sought psychiatric treatment they were now at greater risk for violence," said Dr. Scott Ewing, a psychiatrist who heads the depression and anxiety disorders clinic at McLean Hospital in Belmont, Mass. and who teaches at Harvard Medical School.

"That would only have the effect of discouraging people from getting appropriate treatment, and there's no credible evidence that such people would pose a greater risk to their coworkers," he said.

McDermott's parents, Rosemary and Richard Martinez, told the Globe Thursday that their son became suicidal after a breakup with a girlfriend, while working at the Maine Yankee nuclear power plant in the late 1980s, and was hospitalized for depression at Pembroke (Mass.) Hospital. They said he was seeing a psychiatrist and taking medication at the time of the killings. He has pleaded not guilty.

While stressing that they could not comment on McDermott directly without examining him, Ewing and others cast doubt on one defense theory proposed by McDermott's lawyer - that Prozac or another antidepressant medication helped trigger the Dec. 26 killings at Edgewater Technology in Wakefield, Mass.

Dr. Emil Coccaro, a psychiatry professor at the University of Chicago, said his research showed that drugs such as Prozac, which raise the brain's level of a chemical called serotonin, dampen aggressive impulses in people prone to anger attacks.

Psychiatrists said that in some cases, Prozac or similar drugs could worsen a person's condition - if the patient was misdiagnosed with depression but actually had bipolar disorder, also known as manic depression, or schizophrenia. Because the first signs of manic depression are often hard to distinguish from ordinary depression, it is sometimes misdiagnosed.

But even then, the experts said, a mistakenly prescribed antidepressant would likely trigger agitation or aggression rather than outright violence.

Some researchers have accused Prozac's manufacturer, Eli Lilly, of downplaying side effects including agitation and suicide; the company has denied any link between Prozac and increased risks of violence or suicide.

Coccaro also questioned whether authorities' descriptions of McDermott's actions suggest a biological or pharmaceutical cause.

"These are complex behaviors," he said, referring to reports that McDermott smuggled guns into the office and stalked specific victims. "They suggest premeditation."

But McDermott could use depression as part of a "diminished capacity' defense, in which he is still responsible for his actions but to a lesser degree, said Dr. Ron Schouten, director of the law and psychiatry service at Massachusetts General hospital in Boston. "Someone who is depressed may not be able to cope with very stressful events to the same extent that they would if not depressed."

According to the National Mental Health Association in Alexandria, Va., the vast majority of mentally ill people are not violent and are more likely to be victims than perpetrators of violence.

A study published in the Archives of General Psychiatry in 1998 found that patients discharged from mental hospitals who did not abuse drugs or alcohol were no more likely to commit violence than their well neighbors. Patients with substance abuse problems were five times more likely to be violent than the general population; while non-patients abusing substances were three times more likely to be violent.

Schouten, of Massachusetts General, said mentally ill employees are among the most loyal and punctual. Rather than screening them out, he said, employers should make sure all employees have access to good mental health services. And, he said, they should be willing to intervene if workers display threatening behavior or start having problems taking care of themselves.

"We don't like to get into other people's business," he said, but employers sometimes need to say, "We're worried about you. We think you need to see someone."

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