Nerve Stimulation in Severe Depression
Doctors say that patients with severe depression who do not respond to standard antidepressant therapy benefit from the use of an electronic stimulator.
As a result of a study by scientists at the University of St. Louis School of Medicine in Washington, during which there was a preliminary scan of the brain, scientists identified processes in the brain during stimulation, which showed how the device affects depression. Researchers have found that vagus nerve stimulation leads to changes in brain metabolism before patients begin to feel better.
“Previous studies involving a large number of people have shown that treatment with vagus nerve stimulation in patients with resistant depression yields results,” said the first author of the study, Charles R. Conway, MD, associate professor of psychiatry. “But little is known about how this stimulation works to alleviate depression. We focused on certain areas of the brain known to be responsible for depression.” The Conway team examined 13 people with resistant depression. Their condition did not improve after many months of treatment with five different antidepressants. Most of them were in a similar condition for at least two years, but some patients even had clinical depression for more than 20 years. All participants underwent surgery, during which they had a device inserted into them to electronically stimulate the left vagus nerve. After activation, the device produces a 30-second electronic stimulation of the vagus nerve every five minutes. To establish the effectiveness of treatment at the brain, the researchers performed positron emission tomography (PET) imaging of the brain before stimulation, and then 3 and 12 months after the start of stimulation. In the end, nine out of 13 subjects experienced improvements in the treatment of depression. “We saw very big changes in brain metabolism that took place long before any improvement in mood,” says Conway. “This process, which is taking place, resembles adaptation. The brain begins to function differently. Then the patient’s mood begins to improve. Although patients did not stop taking antidepressants for several months after the stimulants were implanted, many of those who responded positively to the device’s functioning eventually were able to stop taking the medication. “