Depression is one of the most common mental health disorders and a leading cause of disability worldwide. It is estimated to affect 17.3 million American adults with at least one major episode in life(2019). This mood disorder is characterized by recurrent states of low mood and aversion to social engagement or activities. It not only affects a person’s ability to process thoughts and behavior but also alters their sense of well-being. The continuous emotion of sadness and loneliness decreases the productive capacity of an individual, significantly reducing their quality of life.
Currently, a wide range of pharmacologic and nonpharmacologic modalities are widely available to manage depressive disorders. However, these interventions have variable outcomes and are frequently associated with potential side effects that reduce patients’ compliance and further quality of life. Pharmacotherapy is found to be effective in more than half of patients suffering from depression, however, between 20% and 30% of patients exhibit “treatment-resistant depression” (TRD).
Therefore, the need for an alternative approach that is safe, effective, and has greater efficacy than the traditional medication to treat depression has always been of high interest for researchers. This has led to the introduction of the use of electromagnetism to stimulate parts of the brain associated with depression.
Traditional management of depression
Several classes of medication have been marketed under the label of antidepressants that demonstrate efficacy in treating depression. These include selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), and tricyclic antidepressants (TCAs). It is important to note that the therapeutic outcomes of the above-mentioned antidepressants are highly variable and differ from patient to patient. These medications are also associated with potential side effects such as weight gain, sexual dysfunction, body aches, etc. In many cases, resistance to treatment is also observed in a large patient population, requiring increased doses and multiple drugs to achieve near-normal results. This consequently increases the risk of side effects in turn lowering the quality of life.
Electroconvulsive therapy, originally introduced to treat schizophrenia is now being primarily used to treat depression. It is believed to stimulate the brain’s neural activity by induction of a brief set of seizures. ECT although known for its efficacy is limited in its use for the general population. As it requires extensive preparation such as the need for anesthesia, that is known to complicate the recovery process. It is also associated with severe side effects such as memory loss, a deficit in orientation, increased heart rate, and blood pressure that may make it infeasible for cardiac patients.
Why opt for TMS?
Transcranial Magnetic Stimulation is an innovative application of electromagnetic induction to manage and cure multiple neurological and psychiatric disorders. This new advancement is being widely tested and researched all around the globe, with evidence-based therapeutic outcomes seen in the treatment of acute depression. Being a non-invasive treatment modality it has shown to produce effective results without any serious side effects as seen with medications. This painless procedure does not require any surgical intervention or electrode implantation and thus can be employed as a safe alternative to treat depression. Patients just have to sit through multiple sessions over a period of a few weeks to observe improvement in their depressive symptoms. TMS can be employed for both diagnostic and therapeutic purposes. The “single-pulse TMS” is usually used to localize brain functions for research purposes, while “repetitive TMS” (rTMS) is used for clinical treatments.
How does it work?
TMS is proposed to regulate the neural activity in the deeper structures of the brain associated with depression by utilizing an electromagnetic field. During a TMS session, an electromagnetic coil is placed on the scalp that delivers a magnetic pulse to the parts of the brain exhibiting decreased activity due to depression. There are two forms of this procedure, standard TMS and deep TMS. Both the forms are known for their efficacy with the main difference lying in the depth of their penetration.
Studies proving the effectiveness of TMS
In 2008, the FDA approved rTMS as a treatment for adults with depression that does not respond to a single antidepressant medication. Since then multiple pieces of literature have demonstrated the effectiveness of TMS for treating depression.
- A clinical trial published in 2000 assessed the antidepressant effect of transcranial magnetic stimulation in 30 participants with a diagnosed depressive mood disorder. For the purpose of the study, the Hamilton Rating Scale for Depression [HRSD] was employed as an assessment tool to record pre and post-treatment findings. The participants were randomly divided into two groups with one receiving 2 weeks of daily TMS, whereas the other group was placed on a sham trial. It was observed after the clinical trial, that subjects that underwent TMS demonstrated a 50% improvement in the baseline HRSD in comparison to the controlled group.
- Another observational study followed 307 patients with major depressive disorders that underwent TMS for a period of 6 weeks. All the participants of the trial had previously undergone an average of 2.5 antidepressant treatments without observing any satisfactory improvement. The researchers noted a high response rate of 58.0% and a remission rate of 37.1%, post-six-week TMS treatment, respectively. Concluding, TMS to be an effective treatment for those unable to benefit from initial antidepressant medication.
TMS is a well-tolerated procedure, with no evidence of cognitive impairment and with exceedingly rare medical complications. The most commonly observed adverse effects are headache and facial pain post-procedure. Rare cases of seizures have been documented along with impaired working memory. Adverse effects are generally reported with higher however, this risk is substantially decreased with current treatment guidelines. TMS is usually avoided in patients with implanted devices such as cardiac pacemakers.
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