Treatment of Major Depressive Disorder
MDD, also referred to as clinical depression, is a significant medical condition that can affect many areas of life. MDD is one of the most common mental disorders, 1 out of 6 adults experiences depression. Standard treatment of MDD is medication and psychotherapy. However, about a third of patients with MDD do not respond to pharmacotherapy or psychotherapy. For those patients with treatment resistant depression, noninvasive brain stimulation such as repetitive transcranial magnetic stimulation (rTMS) is an emerging option; it uses powerful, focused magnetic field pulses to induce durable changes in the activity of brain regions that are affected by MDD (Bloomberg, 2018). TMS hardly has any side effects.
The use of rTMS in depression has been proven effective and safe in clinical trials for over 20 years (Fitzgerald, 2020); 50% of patients responded significantly to treatment and 15–37% of patients showed a sustaining total absence of depression symptoms.
The standard protocol involves the provision of daily treatment sessions during 37,5 minutes at stimulation frequency of 10 Hz of the targeted brain area (usually the dorsolateral prefrontal cortex or DLPFC), 5 days per week for a minimum of 4 weeks (Bloomberg, 2018). Continuation for another 2 weeks might be an option in case of response failure. Substantially different approaches should be considered only for experimental purposes. rTMS is effective in the treatment of an index episode of MDD and is highly likely to be effective in treating a subsequent episode of relapse. There is limited evidence to support maintenance rTMS treatment although these type of treatments are used widely in clinical practise because of the clinical need.
As provided in the largest multicentre studies, rTMS should be provided at 120% of the resting motor threshold (RMT) or above, and when switching to right DLPFC, low frequency treatment should be considered.
MRI guided neuronavigation with a more accurate localization of DLPFC has the potential to significantly improve clinical outcomes.
