Episode Details

Episode 159: Transcranial Magnetic Stimulation Basics

Future Dr. Ameri explains how transcranial magnetic stimulation can be useful in the treatment of certain mental conditions.  

Written by Omeed Ameri, MS-IV, Western University of Health Sciences, College of Osteopathic Medicine of the Pacific. Editing by Hector Arreaza, MD.

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Transcranial Magnetic Stimulation (TMS)

TMS is a non-invasive procedure that uses magnetic fields to stimulate nerve cells in the brain to improve symptoms of depression and Obsessive-compulsive disorder (OCD). TMS uses the principles of electromagnetic inductions as described by Faraday’s Law. When an electric current passes through the TMS coil, it creates a rapidly charging magnetic field, which passes unimpeded through the scalp and skull, inducing a secondary current in neural tissues of the brain, causing depolarization of neuronal membranes in targeted brain regions, mainly in the superficial layers of the cortex 1.5 to 2.5 cm beneath the coil.

How it works.

Depending on the frequency and pattern of magnetic pulses, TMS can either increase or decrease cortical excitability. High-frequency TMS (Generally > 1 Hz) is associated with increased cortical excitability and is often used for depression treatment. In contrast, low-frequency TMS (< 1 Hz) is typically used for anxiety and pain.

This stimulation alters neurotransmitter release such as dopamine, serotonin, and norepinephrine. The repeated stimulation over sessions promotes synaptic plasticity, leading to more lasting changes in brain activity patterns associated with improved clinical outcomes. This is thought to have cascading effects throughout brain networks, and modulate dysfunctional circuits implicated in depression and restoring normal function. 

Effectiveness.

The effectiveness of TMS can vary widely between individuals due to differences in anatomy, age, and specific conditions being treated. As such, ongoing research into how to personalize and optimize TMS parameters is ongoing. 

Research supporting the use of TMS in treatment-resistant depression.

Research into the effectiveness of TMS and other therapy modalities targeting Treatment-Resistant Depression has been an ongoing effort for many years. In 2009, the American Academy of Family Physicians published Dr. Little’s article titled “Treatment-Resistant Depression,” which noted that there was little evidence that TMS could significantly treat patients with treatment-resistant depression. 

Since that time, the American Journal of Psychiatry published a groundbreaking study in 2020, led by Dr. Cole, which explores the effectiveness of a novel treatment for treatment-resistant depression. This trial, known as Stanford Accelerated Intelligent Neuromodulation Therapy or SAINT, which demonstrates promising results in combating depression where traditional methods have failed. 

It was an open-label study that provides a new perspective on depression treatment, emphasizing rapid and targeted intervention. Twenty-two participants received 50 intermittent theta burst stimulation (iTBS), which is a more recent protocol for TMS treatment, over the course of five days. Each session included 1,800 pulses per session, with a 50-minute intersession interval, ten times a day. As a result of this intensive regimen, one participant withdrew from treatment, and 19 of the remaining 21 met remission criteria, with a score of less than