Transcranial magnetic stimulation promises to be the future for the treatment of depressive disorders.
Instead of antidepressants in pill form, the new frontier in depression treatment is a headset. A device containing electrodes that read brain waves and pass a very slight electric current to the scalp. While receiving the treatment, you can engage in other activities, such as reading, watching a series, listening to music, while your brain activity is being recorded. These and other data, coming from the session and from previous treatments, are entered into an algorithm that continuously perfects the therapeutic path. We have just described a therapy unknown to most of the public, but consolidated for years in clinical practice: Transcranial Magnetic Stimulation (TMS). To talk about itPsyche is Professor Paul Fitzgerald, a psychiatrist and director of the Australian National University School of Medicine and Psychology who has conducted extensive research into the development of new treatments for patients with mental illness and led the clinical development of TMS treatment .
In TMS, a figure-of-eight coil held over the head generates a magnetic field that stimulates localized brain activity and the strength of connections between multiple brain regions. To treat depression, TMS impulses are usually directed to the front of the left side of the brain, a region that is constantly under-activein patients with depression. Several decades of clinical trials have established the efficacy and safety of TMS, especially for patients who have failed to respond to standard antidepressant medications. The lengthy and uncomfortable treatment (patients must attend a clinical setting daily, five days a week, for up to six weeks) coupled with a certain fear about the idea of stimulating the brain with electrical activity, represent an obstacle to this type of treatment.
The many alternatives to pills
New research is underway to develop alternative forms of brain stimulation treatment, with the aim of being able to administer them at the patient’s home.
Among these, research is most advanced for Transcranial Direct Current Stimulation (tDCS), a surprisingly simple process. Unlike TMS, tDCS does not directly stimulate nerve cells in the brain: a weak electric current passes in one direction between two electrodes contained in sponges placed on the scalp. This produces changes in brain activity under the electrodes and, when applied repeatedly to an appropriate area of the brain, has been shown in over 10 clinical studies to help patients with depression. The development of tDCS in depression is in a phase that is progressing rapidly, mainly because its simplicity makes it viable as a widespread home therapy .
On this front, interest has also grown in recent years in a related but distinct form of electrical stimulation: Transcranial Alternating Current Stimulation (tACS), which differs from tDCS in that the applied electrical current passes back and forth between the electrodes alternately rather than in one direction. Probably, because it works through a different mechanism than tDCS, tACS is applied at a specific frequency .
One hypothesis is that depression is associated with miscommunication between the two sides of the front of the brain at the alpha frequency (between 8 and 12 Hz). Fitzgerald explains that it’s important to note that everyone has an “individual alpha frequency,” which can be measured with the electroencephalogram (EEG). This is the specific frequency with which neurons fire when they are in a relevant mental state, such as during rest or when reflecting. If faster or slower stimulation of these networks is found to lead to a therapeutic benefit, tACS could help solve this problem by strengthening communication within the neural networks, or even by slowly adjusting the alpha frequency itself.
The benefits of transcranial stimulation
An advantage of Transcranial AC Stimulation is that it can be customized for each patient. To understand the importance of this new approach, the Australian researcher offers some food for thought: to evaluate patients with depression for the use of tACS stimulation, they should undergo an EEG so that the stimulation can be adapted to their individual alpha oscillation frequency . What Fitzgerald proposes is to measure swings every day at home before, after and perhaps even during the treatment itself, rather than just once in the clinic. This continued reassessment of brain activity could be used to updatethe stimulation parameters, creating a personalized, closed-loop treatment system. The professor and his team believe that all of this could happen and are working on a device that patients could wear while sitting on their sofa.
In addition to this, they are also refining their studies on the ability to continuously update the stimulation parameters on the device through artificial intelligence, cloud-based processes that continuously monitor the results and compare them with previous patient data, creating a flexible system that becomes progressively more effective.
Some recent studies, such as one published in Nature, have indicated that simpler forms of tACS can be used to treat depression although, as mentioned, there have been articles in psychiatric journals which have repeatedly questioned the value of TMS. For this reason, the professor and his colleagues are projected to conduct substantial clinical studies , to convince doctors and regulatory authorities. Fitzgerald pleads his case concluding thus:
There is a risk that a highly innovative treatment, such as home closed-circuit stimulation, will produce some professional resistance , especially since AI-informed treatment could be seen as reducing the doctor’s role in the decision-making process. Existing treatments for depression, such as medications and forms of psychotherapy, are only moderately effective. I hope that soon there will be a new, convenient and personalized option that will have a significant impact on what many are calling the mental health crisis.”
- Double-blind, randomized pilot clinical trial targeting alpha oscillations with transcranial alternating current stimulation (tACS) for the treatment of major depressive disorder (MDD). (nature.com)
