Transcranial magnetic stimulation is a type of treatment used to help people struggling with major depressive disorder. By stimulating the brain, TMS alleviates depressive symptoms. Unique in its use of magnetic fields to stimulate blood flow and affect change in the brain’s mood center, the history of TMS can be traced back to earlier forms of neuromodulation, and the ancient practice of using electric eels for pain relief.
Since then, Transcranial magnetic stimulation has proven to be effective in reducing the symptoms of depression and neuropathic pain, by stimulating the nerves of the prefrontal cortex.
To better understand TMS and its benefits and risk-free procedure, it is important to step back and see how our understanding of the brain, pain, and mental illness have evolved over time. This is the history of TMS and where it came from.
Early History of TMS Development
Neural stimulation as a rudimentary and ancient form of pain relief has existed for thousands of years, but it was not until the eighteenth century – with the invention of the voltaic pile and the first creation of a steady flow of electricity – that its application in medicine began to be thoroughly explored.
Among many theories and potential forms of treatment, one that stood out was the proposal that magnetic waves could affect the brain and cause a change in thinking. When the application of magnetic fields on the brain was first explored in theory, a rudimentary understanding of pain and how it is transmitted throughout the body limited potential research, as the mechanism of pain was not fully understood.
Then, with the advent of the gate control theory in 1965, several new treatments began to emerge off the idea that pain sensations could be prevented from traveling to the CNS through stimulation via non-noxious input. In other words, it was proposed that non-painful input could limit painful input, explained through the relationship between unmyelinated and myelinated nerve fibers.
This led to advancements in neuromodulation, particularly deep brain stimulation to help resolve chronic pain. Other techniques had been explored for decades – one idea that showed promise but was bottlenecked by technological limitations was the practice of using magnetic fields to stimulate the brain. Experimentation on the brain using electromagnetics began after the work of Michael Faraday, the English scientist most known for his Faraday cage, who first proved that we could turn electrical energy into magnetic fields. Using this implication, Jacques-Arsene d’Arsonval discovered that applying magnetic fields to the brain caused vertigo and phosphenes – a spot of light in the eyeball. Although this effect was further studied, it was not until much later that magnetism proved effective in eliciting a positive response in the brain.
In the mid-60s and onwards, several researchers investigated the analgesic effects of stimulating the peripheral nerves in humans and several animals through the non-invasive use of a pulsed magnetic field. Then, in the mid-80s, Dr. Anthony T. Barker explored the application of magnetic fields on the brain, to treat pain and mental illness. This is where the history of TMS truly begins.
TMS in a Modern Era
Dr. Anthony T. Barker introduced Transcranial magnetic stimulation in 1985, continuing the development of the treatment and its technology. Since then, TMS has grown to become a recognized treatment for certain mental health issues in several countries, including the US, UK, Canada, Germany, and Japan. The FDA granted approval of TMS as a treatment for depression in the U.S. in 2008. TMS has proven to be superior to electrical stimulation, because it is pain-free and much easier to implement than electric analogs.
Currently, TMS technology allows for magnetic stimulation up to 2-3 centimeters into the brain. This is enough to elicit a response in the nerves of the prefrontal cortex, thus affecting a patient’s mood. To better understand why this helps with depression, it is important to understand how depression develops in the brain.
Depression in the Brain
Major depressive disorder is a condition described as deep and profound sadness, lasting weeks. It is also described as dysphoria, or an inability to feel joy. Neurologically, depression is expressed by a series of differences in the brain. Among a few other things, these differences affect the way the brain naturally produces and processes the neurotransmitter serotonin. It is not that a person with depression cannot be happy or feel joy. Instead, they are prone to episodes of unexplained sadness, and darkness.
Depression is unfortunately often tied with anxiety, and the two exacerbate one another. Anxiety is, at its core, a condition of constant fear and uncertainty. This stress amplifies the symptoms of depression, and the symptoms of one disease cause the other to grow.
Although often neurological in nature, psychiatric treatment can help alleviate symptoms of depression, and help individuals with a clinical depression achieve a higher quality of life. Antidepressants, like selective serotonin reuptake inhibitors, are used to combat depressive thoughts. Much like TMS, these drugs affect the brain directly, albeit by increasing the amount of available serotonin in the brain rather than affecting the prefrontal cortex’ mood regulation.
TMS as Part of a Your Treatment Plan
While TMS shows immense promise as part of a larger repertoire of modern treatment tools for depression and anxiety, it is still commonly employed when other treatment methods fail.
Factors that tie into depression include neurological differences, brain chemistry, hormones, trauma, stress, substance use, and a family history of mental illness. TMS can help the brain alleviate the portion of the disease affected by a shift in mood. It is most effective at treating major depressive disorder, and cases of treatment-resistant MDD.
TMS is most definitely a treatment that deserves more notice and a greater deal of attention for both its potential, and as a regular form of treatment for many people who struggle with depression, and do not respond adequately to medication, or want a risk-free alternative to SSRIs, SNRIs, and MAOIs. Throughout the history of TMS, we have come a long way from dangerous electric analogs – today, our understanding of neurobiology and magnetism allows us to subtly affect the brain without causing damage or pain.