June 17, 2024

Deep transcranial magnetic stimulation improves depression by reducing excessive slow-frequency brain activity, study suggests

A new study using quantitative electroencephalography (QEEG) found that deep transcranial magnetic stimulation treatment in specific brain regions improves depressive symptoms. This is achieved by reducing slow-wave brain activity in the prefrontal cortex. The study was published in Journal of Affective Disorders.

Major depressive disorder is a mental health condition characterized by persistent feelings of sadness, emptiness, and loss of interest or pleasure in activities that were once enjoyable. It can affect daily life and relationships. In severe cases, people may have thoughts of self-harm or suicide. According to the World Health Organization, around 7% of adults struggle 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. That is 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 done by placing a coil on the head of the person being treated. This coil generates magnetic pulses, which enter the brain and activate or block neural circuits, depending on the goal of the treatment.

Deep TMS is generally considered safe and well tolerated by patients. Side effects, when they occur, are headaches, scalp discomfort, or muscle twitching that disappear after a few weeks.

Author of study 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. To treat major depressive disorder, magnetic stimulation must be directed to the prefrontal cortex and affect neural circuits 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 pioneering treatment approaches for major depressive disorder and other neuropsychiatric conditions,” explained Shanok, director of the Foundation. Delray Center for Brain Scienceassistant professor at Florida Atlantic University, and author of “Purpose Cultivation.”

“Since major depressive disorder is now the leading cause of disability worldwide (according to the World Health Organization), identifying effective treatments is essential to improve the quality of life of people with this condition. Deep TMS has emerged as a successful treatment option with minimal side effects; However, the mechanisms by which TMS affects brain function are still being elucidated.”

“We looked to determine whether a standard course of Deep TMS results in changes in resting brain activity patterns using quantitative electroencephalography (QEEG),” said Shanok. “QEEG is a non-invasive brain activity mapping procedure that could be applied in the clinical psychiatric setting to aid in diagnosis, treatment selection, and objectively tracking progress over time.”

The participants were 44 people diagnosed with major depressive disorder. Twenty-five of them were women. Their average age was 46 years, but individual participants ranged in age from 19 to 80 years. They completed 36 Deep TMS sessions (using the Brainsway dTMS system with both the H1-coil and H7-coil devices). The 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 control 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, the participants completed a general health assessment (Patient Health Questionnaire, PHQ-9) to verify the severity of depressive symptoms and underwent a QEEG recording. The QEEG session lasted 4-6 minutes and the participant was resting with his eyes closed. Recording and assessment were repeated after the last Deep TMS.

Results showed that participants reported a significant reduction in depressive symptoms after treatment compared to the pre-treatment situation. The severity of symptoms ranged from “severe depression” before treatment to “mild depression” afterwards. This reduction was seen in both males and females, but was slightly 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 an improvement in depression symptoms was achieved thanks to this reduction. In addition, they were able to accurately predict which patients would have improvement in symptoms based on QEEG recordings.

“The main finding was that Deep TMS effectively reduced excessive slow-frequency (thermal wave) brain activity in the left and right prefrontal cortex,” Shanok told PsyPost. “These changes were consistent with a significant reduction in depressive symptoms in the study sample. In addition, 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 results provide preliminary support for the beneficial pairing of QEEG with Deep TMS in the clinical setting.”

The study contributes significantly to the development of novel methods for the treatment of 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, and the severity of depressive symptoms was assessed using a self-report measure. This could introduce bias in the participants’ responses which could affect 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,” said Shanok. “The treatment is already FDA approved for major depressive disorder, Obsessive Compulsive Disorder (OCD), smoking cessation, and anxious depression.”

“There is a great opportunity to study the efficacy of Deep TMS for additional indications using QEEG or other brain imaging tools as a guideline for protocol customization. The application of QEEG-guided Deep TMS is particularly attractive for neurodegenerative conditions such as Alzheimer’s disease given the limitations of currently available treatment options.”

The study, “Deep transcranial magnetic stimulation alters resting state neurophysiological characteristics in major depressive disorder”, written by Nathaniel A. Shanok, Santiago Rodriguez, Sabrina Muzac, Carla Huertas Del Pino, Leah Brown, and Raul Rodriguez.

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