https://doi.org/10.1177/1550059417746531 Clinical EEG and Neuroscience 2018, Vol. 49(1) 18–26 © EEG and Clinical Neuroscience Society (ECNS) 2017 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1550059417746531 journals.sagepub.com/home/eeg Special Issue Introduction Schizophrenia (SCZ) affects approximately 1% of the popula- tion and can be considered the most disabling neuropsychiatric disorder. Among the complex clinical picture of SCZ, negative symptoms are among the major determinants of such func- tional impairment and poor quality of life. Indeed, these symp- toms are highly prevalent, are very stable over time and are associated with cognitive impairment. A significant proportion of patients with negative symptoms will continue to experience these symptoms in spite of antipsychotic medication. 1 In a recent review of the literature of negative symptoms, Marder and Galderisi 2 proposed that 5 constructs should be considered as negative symptoms, that is, blunted affect, alogia, anhedo- nia, asociality, and avolition. Also, they have highlighted that the pathophysiology of persistent negative symptoms is still unknown, and these symptoms remain a major challenge in the treatment of those suffering from the disorder. To date, adjunc- tive medications to antipsychotic medication or psychosocial interventions have limited benefit on reduction of negative symptoms. 3-13 However, research is progressively enhancing our understanding of the brain mechanisms that underlie the various symptoms of SCZ. Neuroimaging findings on negative symptoms of SCZ are still inconsistent; however, an association between negative symptoms and gray matter reductions in the prefrontal cortex is often found. 14,15 Moreover, even during rest, hypoactivity of the prefrontal cortex, particularly of the left dorsolateral, and of the anterior cingulate regions, has been linked to negative symptoms of SCZ. 16,17 The striatal dopaminergic hyperactivity 746531EEG XX X 10.1177/1550059417746531Clinical EEG and NeurosciencePontillo et al research-article 2017 1 Child and Adolescence Neuropsychiatry Unit, Department of Neuroscience, Children Hospital Bambino Gesù, Rome, Italy *Maria Pontillo and Floriana Costanzo contributed equally to this work. Corresponding Author: Maria Pontillo, Department of Neuroscience, Children Hospital Bambino Gesù, Piazza Sant’Onofrio 4, I-00165, Rome, Italy. Email: maria.pontillo@opbg.net Use of Transcranial Direct Stimulation in the Treatment of Negative Symptoms of Schizophrenia Maria Pontillo 1* , Floriana Costanzo 1* , Deny Menghini 1 , Roberto Averna 1 , Ornella Santonastaso 1 , Maria Cristina Tata 1 , and Stefano Vicari 1 Abstract Schizophrenia is a debilitating disease that affects approximately 1% of the population. Negative symptoms are among the major determinants of the functional impairment and a significant proportion of patients with negative symptoms will continue to experience these symptoms despite antipsychotic medications. There are promising results in the application of brain stimulation, particularly transcranial direct current stimulation (tDCS), for the reduction of negative symptoms of schizophrenia. However, findings are still controversial. This is a selective review of the literature published between 2011 and 2017 on use of tDCS in treatment of negative symptoms of schizophrenia. We included only randomized controlled trials where schizophrenia and negative symptoms were assessed using any psychometrically validated scale (eg, Positive and Negative Symptoms Scale or Scale for the Assessment of Negative Symptoms). Studies of participants with neurological conditions were excluded, as were those that did not report any symptom outcome variables. Only 5 studies are included. Three studies showed a decrease of negative symptoms. The other studies did not show any therapeutic effects of tDCS in the severity of positive and negative symptoms compared to controls. Our findings suggest that negative symptoms in schizophrenia can be treated with tDCS over the dorsolateral prefrontal cortex, but results are affected by several factors, such as the electrode montage, the concomitant medication, the homogeneity of the sample, the intensity of the tDCS treatment. Further randomized, double-blinded, sham- controlled studies in large samples are still needed to establish the effectiveness of the tDCS in the treatment of negative symptoms in schizophrenia, but there is the potential for tDCS to become a useful complementary treatment option in this population. Keywords tDCS, schizophrenia, negative symptoms, RCT, treatment Received October 18, 2017; revised November 13, 2017; accepted November 14, 2017.