Brain Imaging Shows How Vagus Nerve Stimulation Improves Symptoms of Depression
May 16, 2013
Drs. Conway and Sheline
In a study funded in part by the Brain & Behavior Research
Foundation, Foundation NARSAD Grantees Charles R. Conway, M.D. and Yvette I. Sheline, M.D., and team found that vagus
nerve stimulation (VNS) made positive, long-term changes to the brains of people
suffering from major depression.
Vagus nerve stimulation works by stimulating the vagus nerve (a nerve that runs
from the brainstem to the abdomen) by delivering an electronic pulse for thirty
seconds every five minutes. The study included thirteen patients who had major
depression over the course of two to twenty years who had not responded to
treatment from up to five different antidepressant medications.
Dr. Sheline is well known for her work using brain
scans to learn about depression. She conducted breakthrough research in the
1990s using functional magnetic resonance imaging (fMRI) scans to identify
structural brain changes in the hippocampus and amygdala in depression that
established depression as a brain disease. With a 1998 NARSAD Grant, she went on to use fMRI scans
to identify how antidepressants correct abnormal brain function to alleviate
symptoms of depression.
In the current study, working with Dr. Conway, study
first author and associate professor of psychiatry, Washington
University School of Medicine, St. Louis, MO, and team, positron
emission tomography (PET) brain imaging scans were used to monitor the
treatment’s effects on brain activity in specific regions known to be connected
to depression. Each participant had a PET scan before the initiation of VNS
stimulation, three months into treatment and at twelve months.
After several
months, nine study participants experienced reduced depression symptoms and the
researchers found that VNS brought about changes in brain metabolism weeks or
even months before patients begin to feel better.
Importantly, the researchers also found that VNS affected other deeper structures in the brain, many of which have high concentrations of brain cells that release dopamine, a neurotransmitter that helps control the brain’s reward and pleasure centers and also helps regulate emotional responses. This supports a growing consensus in the field that problems in dopamine pathways may be particularly important in treatment-resistant depression, explains Conway. And he said the finding that vagus nerve stimulators influence those pathways may explain why the therapy can help and why, when it works, its effects are not transient. Patients who respond to VNS tend to get better and stay better.
The study findings were published online on Feb. 15, 2013 in Brain Stimulation.
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