Small, steady shocks delivered to specific areas of the brain may help mentally ill patients, including the millions who suffer from bipolar disorder, a recent study indicates.

Deep brain stimulation (DBS) involves battery-powered electrodes that are surgically implanted in the brain and used to deliver electrical shocks to particular areas. It has already been FDA-approved to treat symptoms of movement disorders, such as Parkinson’s disease, but its use to treat mental illness – e.g., depression, obsessive-compulsive disorder – is still experimental.

In the recent study, 10 patients with major depressive disorder and seven patients with bipolar II disorder were given deep brain stimulation focused on brain circuits known as Area 25 known to control moods. Subjects were only accepted for the study if they scored 20 or more on the Hamilton Depression Rating Scale.

Researchers, led by Emory University neurologist Dr. Helen Mayberg, found a 50 percent drop in Hamilton score after the DBS surgery. Forty-one percent of patients had a positive response to DBS after six months, which rose to 92 percent after two years of DBS. Some patients even went into remission: 18 percent after six months of treatment, and 58 percent after two years.

The findings, published in the journal Archives of General Psychiatry, confirm earlier findings that the benefits of DBS appear to accumulate over time.

Bipolar disorder typically develops during the young adult years, with symptoms appearing by the age of 25 in half of all cases, according to the National Institute of Mental Health.