By Hanna Webster. Mentored and edited by Steven Benowitz.
Research from the Icahn School of Medicine at Mount Sinai in New York and Emory University in Atlanta is providing a new view of depression.
Reporting late last year in Translational Psychiatry, specialists in deep brain stimulation showed in the operating room that stimulating a region deep in the brain called Area 25 decreased certain brain waves, called beta waves. In deep brain stimulation, a procedure used to treat depression and movement disorders like Parkinson’s, beta waves are considered markers for movement.
The scientists, led by Mount Sinai neurologist Helen Mayberg, found that this decrease in beta waves was a neurological signal tied to patient improvement in treatment-resistant depression. Patients in the study described this moment as a “switch” being turned off—almost a minute after stimulation, they had the capacity to move and think in ways that depression had thwarted.
Mayberg presented the research in a virtual talk called “Tracking Brain Dynamics to Optimize Deep Brain Stimulation for Depression,” at the 2022 American Association for the Advancement of Science (AAAS) Annual Meeting on February 18.
For a patient to be classified as treatment-resistant, she must be unresponsive to at least four antidepressant treatments. Deep brain stimulation has abated many of these patients’ depression symptoms. The procedure involves inserting a thin wire with one centimeter length of electrodes at the tip into the relevant brain region while the patient is awake. A device similar to a pacemaker goes under the patients’ skin near the collarbone, providing battery power for the device and allowing current to run through the wire and into the targeted brain region.
In a 2005 study, Mayberg and her colleagues zeroed in on that targeted brain region. They hypothesized that an overactive Area 25 created “intense negative mood,” and that deep brain stimulation in this area could reduce brain activity, alleviate symptoms, and lead to more activity in connected brain regions responsible for planning and action.
“Depressed people have maladaptive habits,” said Mayberg, speaking at an AAAS Scientific Session also on February 18, called “Decoding Brain Signals to Treat Disorders of Mood, Motor, and Communication.” By stimulating Area 25, deep brain stimulation allows the foot to be taken off the pedal, so to speak, so patients can resume learning and engage other parts of their brain.
The beta signal decrease seen in the Translational Psychiatry study accompanied a decrease in patient scores in a common depression rating scale by 45.6%. That is a jump from moderate to severe depression to mild depression. The magnitude of left hemisphere Beta decrease could also determine how well patients were doing a week later, and seven out of eight participants continued to see lower depression scores after six months of treatment.
Evidence of a beta wave decrease in depressed patients supports the idea that major depression is a movement disorder, not a mood disorder, Mayberg said in the AAAS Scientific Session. For depressed patients who experienced the “switch” moment in the operating room, the beta signal decrease temporarily lifted symptoms of immobility seen in major depression. “It’s as if they’re paralyzed, and then they’re not,” said Mayberg.
Deep brain stimulation is largely safe for patients. While Mayberg said risk will always be a factor when considering treatment, scientists should also consider the implications of not treating. When other treatments have failed them, deep brain stimulation has provided many patients with relief. With these findings, Mayberg’s team might soon be able to uncover how deep brain stimulation might cause long-term changes in the brain that lead to visible improvements in the lives of her patients.
Hanna Webster is a San Diego-based science writer, poet, and graduate student in the Johns Hopkins University Science Writing Program. With a degree in behavioral neuroscience and creative writing from Western Washington University, she enjoys writing stories about public health, psychology, and sociology. You can find her work in Leaps.org, The Science Writer, Leafly, and more.
Image Credit: Ben Sweet on Unsplash
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