Chicago ? Patients with advanced Parkinson’s disease who received deep brain stimulation showed greater improvement in movement and quality of life after six months than those treated with medication, a new study shows.

But the deep brain stimulation patients also had an almost four times greater risk of suffering a serious adverse event like depression, infections, falls or heart problems. While most side effects could be treated, one patient suffered a brain hemorrhage and died.

With deep brain stimulation, doctors surgically implant electrodes that send electrical stimulation to specific parts of the brain to reduce involuntary movements and tremors. It is a widely accepted treatment for advanced Parkinson’s disease, but few randomized trials have been conducted comparing different treatments.

Previous studies also have largely excluded older patients, who account for the majority of those with the disease. About 25 percent of the more than 250 patients in the new study were 70 or older.

In the study, which appears in this week’s Journal of the American Medical Association, patients were randomly selected to receive either medication or bilateral deep brain stimulation, with the leads implanted into the subthalamic nucleus or the globus pallidus areas of the brain.

Lead study author Frances Weaver said researchers were surprised by the magnitude of the differences in outcomes between the surgical and medical treatments.

“The amount of time that patients were able to move normally increased by 4.6 hours,” said Weaver, director of the Center for Management of Complex Chronic Care at Hines VA Hospital in west suburban Hines. “Our best medical therapy patient, on average, showed no improvement.”

Researchers studied how long patients had good motor control — referred to as “on” time — without experiencing dyskinesia — the jerky, uncontrolled movements patients develop after long-term use of medications that treat Parkinson’s disease.

The new research is the first to show that deep brain stimulation works as well in older patients as in younger ones, said Dr. Leo Verhagen, a neurologist and medical director of the movement disorders surgery program at Rush University Medical Center in Chicago, who was not involved with the study.

Weaver was optimistic about the findings, but said deep brain stimulation is not a panacea.

“It certainly helps a lot of people,” she said, “but it doesn’t address all of the issues of Parkinson’s disease, which is a progressive, degenerative neurological disease — second only to Alzheimer’s. So other things will continue to get worse, such as memory, speech, writing, information processing and bladder management.”

The study — conducted at seven VA hospitals and six affiliated academic medical centers across the country between May 2002 and October 2005 — required patients to keep diaries documenting their motor and physical functioning throughout the day. Neurologists assessed patients’ motor skills without knowing which patients got which treatment.