TMS is an ideal treatment option for people who have not benefitted from psychiatric medications, had intolerable medication side effects, or for anyone who is looking for an alternative to medications to treat their depression or obsessive-compulsive disorder. TMS is a well-tolerated treatment that can avoid the side effects that often accompany taking a daily medication or can augment the response to a daily medication.
Many people who have major depression do not respond to antidepressant medications or are unable to tolerate medications due to side effects. Some people have a “partial response,” but suffer from considerable residual symptoms of depression while taking antidepressants.
The more medications that someone has tried without benefit, the less likely they are to respond to subsequent medication trials for their depression, and the more likely they are to suffer from medication side effects.
When someone has not had full relief from one or two antidepressant medications, they are diagnosed with “treatment-resistant depression,” (TRD) and at this point most insurance plans will cover a course of once-daily, conventional transcranial magnetic stimulation.
Transcranial Magnetic Stimulation (TMS) is a non-invasive procedure that uses magnetic fields to stimulate specific regions of the brain. It involves the use of a device called a TMS coil, which generates pulsing magnetic fields, similar in type and strength to the magnetic fields created by MRI (Magnetic Resonance Imaging) machines.
TMS is an example of Faraday’s law of electromagnetism in action: an electrical current coursing through a circuit creates a perpendicular magnetic field. This fundamental principle has been harnessed in TMS treatment, where an electromagnetic coil is placed on the scalp, and the pulsing magnetic fields produced by the coil penetrate the scalp and skull unimpeded, without causing any harm, and stimulate the underlying brain tissue.
Since the brain is an electrochemical organ, the pulsing magnetic fields created by the TMS coil can stimulate or inhibit the firing of the neurons (brain cells) in targeted brain regions.
By adjusting the parameters of the TMS device, such as the frequency and intensity of the induced magnetic pulses, a TMS coil can selectively stimulate or suppress specific brain areas.
The most widely studied and clinically utilized protocols for TMS treatment of depression stimulate an area of the brain known as the “left dorsolateral prefrontal cortex,” or the LDLPFC for short.
Several converging lines of evidence, including functional neuroimaging (fMRI or PET), EEG (electroencephalogram), and lesion studies support the hypothesis the LDLPFC is underactive in depression.
There is also an FDA-cleared coil and protocol used to target more midline structures (medical prefrontal cortex and anterior cingulate cortex) to help alleviate symptoms of obsessive-compulsive disorder (OCD).
Conclusion
Transcranial Magnetic Stimulation (TMS) is a non-invasive and well-tolerated treatment option for individuals with major depressive disorder and obsessive-compulsive disorder. By utilizing magnetic fields to stimulate specific brain regions, TMS offers an alternative to traditional medication-based approaches.
TMS protocols targeting the LDLPFC have shown consistent antidepressant efficacy, while other protocols target other brain regions indicated in different mental illnesses.
With its various coil designs and adjustable parameters, TMS allows for selective stimulation or suppression of specific brain areas, avoiding systemic side effects common with antidepressants or other psychiatric medications.
TMS is FDA-cleared and provides a promising avenue for individuals seeking safe and effective non-invasive treatments for depression and OCD; evidence is accumulating that TMS can help reduce cravings in alcohol and other substance use disorders, alleviate fatigue in multiple sclerosis and “brain fog” due to fibromyalgia or long Covid, and reduce social anxiety in people with autism, though TMS is not yet FDA-cleared for these indications.
