Transcranial direct current stimulation in psychiatry: Mood disorders, schizophrenia and other psychiatric diseases

Abstract

This chapter first provides an overview of tDCS use in psychiatry discussing some appealing characteristics for its use such as ease of use, portability, low cost, absence of serious adverse effects and possibility of pharmacotherapy augmentation. After that, the clinical evidence of tDCS efficacy in several psychiatric disorders is discussed. Major depressive disorder is the first presented condition, as most studies in psychiatry investigated tDCS efficacy in depression. Although early results were mixed, more recent studies show superiority against placebo. Putative mechanisms of action are also discussed. After that, positive results from tDCS efficacy in ameliorating auditory hallucinations in patients with schizophrenia are presented, as well as subsequent studies showing negative or mixed results in patients with positive and negative symptoms. TDCS application in other conditions such as bipolar disorder, anxiety disorders, obsessive-compulsive disorder, post-traumatic stress disorders, addiction and other psychiatric disorders, which is still in its infancy, are also discussed. To conclude, the most promising results to date are tDCS effects for depression and certain symptoms of schizophrenia, although it is still unclear which parameters of stimulation result in optimal therapeutic effects and in which groups of patients tDCS is most effective; therefore, further studies are warranted. Moreover, the mechanisms of action of tDCS relevant for clinical effects are largely unknown, reinforcing the need of more clinical studies combining tDCS with neuroimaging, electrophysiology, neuropsychology and other investigational techniques.