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A new study utilizing quantitative electroencephalography (QEEG) has found that deep transcranial magnetic stimulation treatment of specific brain regions improves depressive symptoms. This is achieved by reducing slow-wave brain activity in the prefrontal cortex. The study was published in the Journal of Affective Disorders.
Major depressive disorder is a mental health condition characterized by persistent feelings of sadness, emptiness, and a loss of interest or pleasure in activities that were once enjoyable. It can interfere with daily life and relationships. In severe cases, individuals may have thoughts of self-harm or suicide. According to the World Health Organization, approximately 7% of adults cope with major depressive disorder. It is a leading cause of disability worldwide.
Initial treatments for major depressive disorder include antidepressant medication and psychotherapy. However, between 30% and 50% of individuals diagnosed with this disorder retain symptoms after completing treatments. This condition is referred to as treatment-resistant depression. It is the reason why scientists are looking for new ways to treat major depressive disorder. One such approach is deep transcranial magnetic stimulation.
Deep transcranial magnetic stimulation (Deep TMS) is a non-invasive medical procedure that involves using a device that generates magnetic fields to stimulate specific areas deep within the brain. Usually, the treatment is conducted by placing a coil on the head of the person undergoing treatment. This coil generates magnetic pulses, which penetrate into the brain and activate or inhibit neural circuits, depending on the treatment goal.
Deep TMS is generally considered to be safe and patients tolerate it well. Side effects, when they occur, consist at most of headaches, scalp discomfort, or muscle twitching that disappears after a few weeks.
Study author Nathaniel A. Shanok and his colleagues wanted to evaluate the effects of a standard course of Deep TMS treatments on brain activation patterns during rest. For treatment of major depressive disorder, magnetic stimulation needs to be directed at the prefrontal cortex and to affect neural circuitry that lies between this region and parts of the brain involved in mood regulation including the limbic system and the subgenual cingulate cortex.
“Our team is particularly interested in cutting-edge treatment approaches for major depressive disorder and other neuropsychiatric conditions,” explained Shanok, the director of the Delray Center for Brain Science, an adjunct professor at Florida Atlantic University, and the author of “Pursuing Purpose.”
“Given that major depressive disorder is now the leading cause of disability worldwide (according to the World Health Organization), it is vital to identify effective treatments for improving the quality of life of those living with this condition. Deep TMS has emerged as a successful treatment option with minimal side effects; however, the mechanisms by which TMS influences brain functioning are still being elucidated.”
“We sought to determine whether a standard course of Deep TMS leads to changes in resting-state brain activity patterns using quantitative electroencephalography (QEEG),” Shanok said. “QEEG is a non-invasive brain activity mapping procedure that could be implemented in the clinical psychiatric setting to aid with diagnosis, treatment selection, and objectively tracking progress over time.”
Participants were 44 individuals diagnosed with major depressive disorder. Twenty-five of them were women. Their average age was 46 years, but age of individual participants ranged between 19 and 80 years. They completed 36 Deep TMS sessions (using a Brainsway dTMS system with both the H1-coil and H7-coil devices). Participants received two treatments in each session, using each of the two coils and targeting different regions of the brain. These treatments lasted 9 weeks.
The H1-coil was used to stimulate deep prefrontal cortex areas including the dorsolateral region with preferential targeting of the left hemisphere. This area is believed to regulate sustained attention, executive functions and decision making. The H-7 coil was used to stimulate the medial prefrontal cortex and structures in the anterior cingulate cortex when placed 2–4 cm from the intersection of the forehead and the two nasal bones.
Before the first Deep TMS session, participants completed a general health assessment (the Patient Health Questionnaire, PHQ-9) to verify the intensity of depressive symptoms and underwent QEEG recording. The QEEG session lasted 4-6 minutes during which the participant was resting with eyes closed. The recording and the assessment were repeated after the last Deep TMS.
Results showed that participants reported significant reduction in depression symptoms after the treatment compared to the situation before the treatment. The intensity of symptoms went from “severe depression” before the treatment to “mild depression” afterwards. This reduction was observed in both males and females, but it was somewhat more pronounced in males.
The QEEG recordings showed reduced slow-frequency brain activity (delta and theta waves) in the prefrontal cortex after treatments. The researchers believe that the improvement of depression symptoms was achieved thanks to this reduction. Additionally, they were able to accurately predict which patients would experience an improvement in symptoms based on QEEG recordings.
“The key finding was that Deep TMS effectively reduced excessive slow-frequency brain activity (theta wave) in the left and right prefrontal cortex,” Shanok told PsyPost. “These changes corresponded with a significant reduction of depressive symptoms in the study sample. Additionally, baseline QEEG activity in the frontal lobe predicted whether a participant would be a responder or non-responder to the treatment with 93 percent accuracy. These findings provide preliminary support for the beneficial pairing of QEEG with Deep TMS in the clinical setting.”
The study makes an important contribution to the development of novel methods for treating major depressive disorder. However, it should be noted that the number of participants in the study was small, they knew the goal of the study and what the researchers expected, while the intensity of depressive symptoms was assessed using a self-report measure. This could have introduced a bias in participants’ responses that could have affected the results.
“One of the important remaining questions is whether Deep TMS can be leveraged to treat a variety of neuropsychiatric conditions including attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), substance use disorder, dementia, Alzheimer’s disease, and Parkinson’s disease,” Shanok said. “The treatment is already FDA-approved for major depressive disorder, Obsessive Compulsive Disorder (OCD), smoking cessation, and anxious depression.”
“There is a compelling opportunity to study the efficacy of Deep TMS for additional indications using QEEG or other brain imaging tools as a guiding point for protocol customization. The application of QEEG-guided Deep TMS is particularly appealing for neurodegenerative conditions like Alzheimer’s disease considering the limitations of currently-available treatment options.”
The study, “Deep transcranial magnetic stimulation alters resting-state neurophysiological traits in major depressive disorder”, was authored by Nathaniel A. Shanok, Santiago Rodriguez, Sabrina Muzac, Carla Huertas Del Pino, Leah Brown, and Raul Rodriguez.
