Use of transcranial direct current stimulation for the treatment of auditory hallucinations of schizophrenia – a systematic review
Received 10 September 2016
Accepted for publication 2 December 2016
Published 1 February 2017 Volume 2017:13 Pages 347—355
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Colin Mak
Peer reviewer comments 3
Editor who approved publication: Dr Roger Pinder
Pedro H Pondé,1 Eduardo P de Sena,2 Joan A Camprodon,3 Arão Nogueira de Araújo,2 Mário F Neto,4 Melany DiBiasi,5 Abrahão Fontes Baptista,6,7 Lidia MVR Moura,8 Camila Cosmo2,3,6,9,10
1Dynamics of Neuromusculoskeletal System Laboratory, Bahiana School of Medicine and Public Health, 2Postgraduate Program in Interactive Process of Organs and Systems, Federal University of Bahia, Salvador, Bahia, Brazil; 3Laboratory for Neuropsychiatry and Neuromodulation and Transcranial Magnetic Stimulation Clinical Service, Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; 4Scientific Training Center Department, School of Medicine of Bahia, Federal University of Bahia, Salvador, Bahia, Brazil; 5Neuromodulation Center, Spaulding Rehabilitation Hospital, Harvard Medical School, Boston, MA, USA; 6Functional Electrostimulation Laboratory, Biomorphology Department, 7Postgraduate Program on Medicine and Human Health, School of Medicine, Federal University of Bahia, Salvador, Bahia, Brazil; 8Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; 9Center for Technological Innovation in Rehabilitation, Federal University of Bahia, 10Bahia State Health Department (SESAB), Salvador, Bahia, Brazil
Introduction: Auditory hallucinations are defined as experiences of auditory perceptions in the absence of a provoking external stimulus. They are the most prevalent symptoms of schizophrenia with high capacity for chronicity and refractoriness during the course of disease. The transcranial direct current stimulation (tDCS) – a safe, portable, and inexpensive neuromodulation technique – has emerged as a promising treatment for the management of auditory hallucinations.
Objective: The aim of this study is to analyze the level of evidence in the literature available for the use of tDCS as a treatment for auditory hallucinations in schizophrenia.
Methods: A systematic review was performed, searching in the main electronic databases including the Cochrane Library and MEDLINE/PubMed. The searches were performed by combining descriptors, applying terms of the Medical Subject Headings (MeSH) of Descriptors of Health Sciences and descriptors contractions. PRISMA protocol was used as a guide and the terms used were the clinical outcomes (“Schizophrenia” OR “Auditory Hallucinations” OR “Auditory Verbal Hallucinations” OR “Psychosis”) searched together (“AND”) with interventions (“transcranial Direct Current Stimulation” OR “tDCS” OR “Brain Polarization”).
Results: Six randomized controlled trials that evaluated the effects of tDCS on the severity of auditory hallucinations in schizophrenic patients were selected. Analysis of the clinical results of these studies pointed toward incongruence in the information with regard to the therapeutic use of tDCS with a view to reducing the severity of auditory hallucinations in schizophrenia. Only three studies revealed a therapeutic benefit, manifested by reductions in severity and frequency of auditory verbal hallucinations in schizophrenic patients.
Conclusion: Although tDCS has shown promising results in reducing the severity of auditory hallucinations in schizophrenic patients, this technique cannot yet be used as a therapeutic alternative due to lack of studies with large sample sizes that portray the positive effects that have been described.
Keywords: auditory hallucinations, tDCS, schizophrenia, non-invasive brain stimulation
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