Transcranial direct current stimulation: a promising alternative for the treatment of major depression?

Objective: In recent years, a number of new somatic (non-pharmacological treatments) have been developed for the treatment of major depression and other neuropsychiatric disorders. Among these, one of the most promising is transcranial direct current stimulation. Method: For the present literature review we searched the PubMed between January 1985 and February 2009. To be included, articles should have been published in English and should address general principles of transcranial direct current stimulation and its use in major depression. Discussion: Current protocols for the treatment of major depression with transcranial direct current stimulation usually involve the application of two sponge-electrodes in the scalp. In general, the positive electrode is applied in the region above the left dorsolateral prefrontal cortex (i.e., F3 region of the 10/20 International System for EEG) and the negative electrode is applied in the region above the right supra-orbital area. A direct electrical current of 1-2 mA is then applied between the electrodes for about 20 minutes, with sessions being daily performed for one to two weeks. Initial studies (including a randomized, double-blind, placebo-controlled clinical trial) showed that transcranial direct current stimulation is effective for the treatment of non-complicated major depression and that this technique, when used in depressed patients, is associated with improvement in cognitive performance (including working memory). Finally, transcranial direct current stimulation is safe and well tolerated. Conclusion: Recent studies show that transcranial direct current stimulation is an important neuromodulatory method that may be useful for the treatment of depressed patients. However, further studies are needed to better clarify its precise role in the management of depressive disorders.