Emotion Recognition Deficits in Psychiatric Disorders as a Target of Non-invasive Neuromodulation: A Systematic Review

Background. Social cognition deficits are a core feature of psychiatric disorders, such as schizophrenia and mood disorder, and deteriorate the functionality of patients. However, no definite strategy has been established to treat social cognition (eg, emotion recognition) impairments in these illnesses. Here, we provide a systematic review of the literature regarding transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS) for the treatment of social cognition deficits in individuals with psychiatric disorders. Methods. A literature search was conducted on English articles identified by PubMed, PsycINFO, and Web of Science databases, according to the guidelines of the PRISMA statement. We defined the inclusion criteria as follows: (1) randomized controlled trials (RCTs), (2) targeting patients with psychiatric disorders (included in F20-F39 of the 10th revision of the International Statistical Classification of Diseases and Related Health Problems [ICD-10]), (3) evaluating the effect of tDCS or rTMS, (4) reporting at least one standardized social cognition test. Results. Five papers (3 articles on tDCS and 2 articles on rTMS) met the inclusion criteria which deal with schizophrenia or depression. The significant effects of tDCS or rTMS targeting the left dorsolateral prefrontal cortex on the emotion recognition domain were reported in patients with schizophrenia or depression. In addition, rTMS on the right inferior parietal lobe was shown to ameliorate social perception impairments of schizophrenia. Conclusions. tDCS and rTMS may enhance some domains of social cognition in patients with psychiatric disorders. Further research is warranted to identify optimal parameters to maximize the cognitive benefits of these neuromodulation methods.