CHICAGO (AP) -- Doctors may want to give stroke victims antidepressants right away instead of waiting until they develop depression, a common complication, new research suggests.

The findings may lead to an expanded use for antidepressants. Someday high-risk people like stroke patients might take the drugs before suffering depression -- just as people now take cholesterol drugs to prevent heart attacks, the lead author said.

The researchers gave low doses of the antidepressant Lexapro to stroke patients. The patients on the drug were 4.5 times less likely to develop depression than patients taking a dummy pill.

More than 700,000 Americans suffer strokes each year and more than one-third will develop depression in the next two years. Stroke patients with depression recover more slowly and are more likely to die, according to previous research.

"We showed you could in fact prevent the development of depression after stroke," said Dr. Robert Robinson of the University of Iowa who led the study. "I hope I don't have a stroke, but if I do, I would certainly want to be placed on an antidepressant."

Experts say strokes may damage parts of the brain affecting mood. Add to that the stress of relearning simple tasks and adjusting to stroke-caused impairments and you've got a recipe for depression.

Lexapro may work by making the chemical serotonin more available in the brain and by promoting brain repair, said Dr. George Bartzokis of the University of California, Los Angeles, who was not involved in the new study.

"Treating the depression may actually help treat the stroke and vice versa," Bartzokis said.

The study, appearing in Wednesday's Journal of the American Medical Association, was based on an analysis of 176 stroke patients, ranging in age from 50 to 90.

At the start, none suffered from depression. One-third were randomly assigned to take Lexapro. One-third took matching dummy pills. And one-third were assigned to receive talk therapy focusing on problem-solving skills.

After one year, about 9 percent of the Lexapro group had developed depression. That compared to 22 percent of the placebo-takers and 12 percent of the people who got problem-solving therapy.

Side effects such as dry mouth, dizziness, rapid heart rate and sexual problems were reported by all three groups at about the same rates.

Lexapro costs about $80 per month. A generic version of a similar drug costs about $40 per month and might be as effective, Robinson said.

Dr. Charles Reynolds, a geriatric psychiatrist at the University of Pittsburgh Medical Center, said he hopes doctors will start prescribing preventive antidepressants to stroke patients.

"Depression in the wake of a stroke amplifies the suffering and disability such patients experience," Reynolds said.

"Dr. Robinson's work supports a novel way of preventing such suffering and disability."

But with prevention, some patients take pills who never would have needed them, putting them at risk for unnecessary side effects. Seven stroke patients would have to be treated with antidepressants to prevent one depression, the researchers found.

Robinson said that's acceptable, especially when compared to the current standards in heart attack prevention. He cited a study showing it takes 40 male patients taking cholesterol-lowering statins over five years to prevent just one heart attack.

The researchers excluded from the study patients who had cancer, other life-threatening conditions or severe verbal impairments, so the findings may not apply to all stroke patients.

The research was funded by the National Institute of Mental Health.

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