Deep brain stimulation could become a useful way to treat depression and obsessive-compulsive disorder (OCD), results of two of the largest and longest studies revealed.

OCD is a psychiatric anxiety disorder marked by recurrent and persistent thoughts and impulses, such as uncontrollable and repeated hand washing.

Deep brain stimulation is used for some people with Parkinson’s disease, essential tremor and dystonia.

According to Dr. Ali Rezai, head of neurosurgery at the Cleveland Clinic’s Center for Neurological Restoration, who led the studies, deep brain stimulation helped the most severely depressed patients improve significantly.

Researchers from Butler Hospital-Brown Medical School, Massachusetts General Hospital and Harvard medical school were also involved in the depression study.

Eight of the 16 patients participating in one of the studies, previously diagnosed as having depressive disorder, showed at least 50 percent improvement in depression scores after one-year follow-up period, Dr. Rezai said during an interview on Monday, MedPage Today reported.

The results of the study, called Deep Brain Stimulation for the Treatment of Depression: Long Term Outcomes from a Prospective Multi-Center Trial, will be presented by Dr. Rezai on Tuesday during the 76th Annual Meeting of the American Association of Neurological Surgeons in Chicago. Medtronic Inc. supported the study.

The patients were treated with Medtronic’s deep brain stimulation device. The “brain pacemaker” is implanted in the chest, with leads that send electrical impulses to parts of the brain that are functioning abnormally. The impulses block the abnormal activity in the brain, which causes a variety of symptoms, such as pain, tremors, movement problems, as well as obsessions, moods and anxieties associated with psychiatric disorders.

Before the study, the patients had severe and disabling major depression lasting at least five years without response to at least three classes of antidepressants titrated to the highest tolerated doses.

“This research substantiates our earlier findings, which indicate that bilateral DBS of the anterior limb of the internal capsule holds promise and hope for select patients suffering from severe and treatment resistant major depression. [Responders] had significant improvement in quality of life, returning back to work, getting engaged, dating,” Dr. Rezai said.

The brain pacemaker, manufactured by Medtronic Inc., was also effective in treating OCD, Dr. Rezai said. The trial included 26 patients who were followed for three years.

There were no major adverse effects such as hemorrhage or infection. Just one patient reported discomfort from the leads, which resolved after they were relocated. Two patients had a return of depressive symptoms and suicidal ideation when their pulse generators were accidentally turned off, but symptoms improved once they were restarted, Dr. Rezai said.

 He also added that the next step would be a randomized, controlled trial.