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August 4, 2008
Study shows promise for patients with treatment-resistant depression

By Kathi Baker

A study by Emory neuroscientist Helen Mayberg and researchers at the University of Toronto found that deep brain stimulation (DBS) is safe and improves depression symptoms in patients who have been unresponsive to most other treatments. DBS uses high-frequency electrical stimulation targeted to specific areas of the brain involved in neuropsychiatric disease, in this case the subcallosal cingulate region (Cg25).

The clinical trial is the culmination of Mayberg’s 20 years of research using imaging technology to characterize functional brain abnormalities in major depression and to identify the mechanisms of various antidepressant treatments.

“In previous studies using brain imaging, we found the subcallosal cingulate region was a key region in an emerging emotion regulation circuit implicated in major depression,” explains Mayberg.

“We postulated that if stimulation worked for the treatment of other neurological disorders where abnormal function of specific circuits was well established, such as Parkinson’s disease, then stimulation of the Cg25 region within this apparent depression circuit might provide significant benefit for patients with treatment-resistant depression.”

Twelve of 20 patients experienced a significant decrease in depressive symptoms by six months, with seven patients essentially well with few remaining symptoms. Benefits were largely maintained at 12 months with continued stimulation, and patients experienced no long-term side effects.

PET imaging showed that metabolic activity changed locally at the site of stimulation but also throughout the previously identified depression network.

“We see depression as a complex disturbance of the specific circuits in the brain responsible for regulating mood and emotions,” Mayberg says. “We hypothesized that if DBS could locally modulate a critical central location within this mood circuit, such modulation would result in clinical improvement — and it appears it does.”