Deep Brain Stimulation (DBS) was developed in the late 1980s. However, it was not tested as a potential treatment for resistant depression until Helen Mayberg, M.D., and colleagues in Toronto, used a NARSAD Distinguished Investigator Grant in 2003 to conduct pilot studies. In work published online April 11th in Biological Psychiatry, a new brain-mapping study by Dr. Mayberg and her research team at Emory University has revealed why DBS is successful for some patients and, importantly, how this information can now be applied to make it succeed for more patients.
In her 2003 pilot study published in the journal Neuron in 2005, Dr. Mayberg hypothesized that DBS could be targeted to a section of the brain called the subcallosal cingulate (also known as “Brodmann Area 25”) that she had earlier identified as linked to depression. She and others have gone on to demonstrate that by targeting the subcallosal cingulate (SCC), DBS can greatly reduce depression symptoms in up to as many as two-thirds of treatment-resistant patients and in some cases can result in sustained long-term remission.
The new study used highly refined magnetic resonance imaging (MRI) combined with computerized analysis to identify white-matter network connections in and out of the SCC region in the brains of 16 patients who had been treated with DBS for resistant depression at the Emory University School of Medicine, where Dr. Mayberg is a Professor of Psychiatry, Neurology and Radiology. The research study led by psychiatrist Patricio Riva Posse, M.D., and biomedical engineer Ki Sueng Choi, Ph.D., found that all the six-month and two-year responders to DBS showed a common pattern of stimulation affecting three distinct white-matter bundles passing through the SCC. Non-responders did not show the full three-bundle pattern. After this finding, the researchers were able to successfully convert six patients who were not initially responsive to treatment by changing DBS stimulation to include all three bundles.
In DBS, a pair of electrodes is implanted in the brain and connected by wires to a pair of pulsing devices in the chest (this is why it is sometimes described as a “pacemaker” for the brain). One hypothesis is that DBS creates a sort of jamming signal to the targeted brain circuits, while leaving other circuits intact.
"Precisely delineating these white matter connections appears to be very important to a successful outcome with this procedure,” commented Dr. Mayberg. “From a practical point of view, these results may help us to choose the optimal contact for stimulation and eventually to better plan the surgical placement of the DBS electrodes. That said, improving anatomical precision alone doesn't account for all non-responders, so that is an important next focus of our research."