Non-invasive electrical AC stimulation alleviates depression symptoms

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Morgan Alexander et al. / Translational Psychiatry, 2019


American scientists conducted an initial study into the use of alternating current transcranial electrical stimulation to treat depression. By restoring the synchronization of the activity of the frontal lobes in the alpha rhythm, they were able to reduce the symptoms of depression and preserve the result for four weeks. Article published in the journal Translational psychiatry.

Antidepressants (mainly drugs from the group of serotonin reuptake inhibitors) and psychotherapy are now used to treat depression. However, the effectiveness of these methods for each patient is different and it is difficult to predict in advance. In addition, both treatments have their own side effects and neither ensures that the disease does not recur.

Researchers are therefore developing new methods that will not only be effective in the treatment of depression, but will also not have the disadvantages observed in drugs and psychotherapy. One of these methods is invasive and non-invasive electrical stimulation and magnetic stimulation of the brain. Thus, last year, scientists were able to help patients with depression through invasive stimulation of the orbitofrontal cortex, and earlier – to reduce suicidal tendencies during depression using transcranial magnetic stimulation.

In the new work, scientists led by Morgan Alexand (Morgan Alexander) of the University of North Carolina at Chapel Hill decided to relieve the symptoms of depression by using transcranial AC stimulation (tACS). This method of non-invasive stimulation allows current discharges to the cerebral cortex to be initiated in harmony or dissonance with its own electrical activity.

The study included 32 volunteers with depression. For five days they were stimulated with alternating current with a frequency of 10 Hertz, 40 Hertz and "empty" stimulation (placebo stimulation): the stimulation was given non-invasively to the frontal lobes.

One of the abnormalities of brain activity observed during depression is the desynchronization of right and left forehead lobes in the alpha rhythm (from 8 to 14 Hertz). Scientists have suggested that leveling activity with stimulation in 10 Hertz can relieve the symptoms of depression, in particular – impaired cognitive functions, for which the work of the frontal lobes is responsible.

By the end of the five-day stimulation, the symptoms of depression in all study participants were reduced regardless of the condition. However, after two and four weeks the effect remained only in the group whose participants received stimulation with a frequency of 10 Hertz; the symptoms returned in all other groups.

Regarding the leveling of the activity of the frontal lobes in the alpharhythm, this was also mainly achieved in the group that received stimulation with a frequency of 10 Hertz: this is why scientists have concluded that the improvement of the patient's condition is a consequence of a change in the activity of their brains.

Based on the results of their pilot study, scientists concluded that transcranial stimulation of the frontal lobes of the brain with alternating current can be used effectively in the treatment of depression. However, they clarify that in the following studies it is necessary to extend the observation period and to investigate the potential of a different stimulation dose.

Scientists have previously shown that the use of alternating current stimulation can also improve the working memory: this must be done in a theta rhythm.

Elizaveta Ivtushok