Transcranial direct current stimulation improves tardive dyskinesia in long-term hospitalized patients with chronic schizophrenia

•TDCS improved facial-oral motor symptoms among patients with TD.•The treatment effect of 15 sessions of tDCS was significantly better than that of 10 sessions of tDCS.•TDCS is safe and well-tolerated in the treatment of patients with TD. This study aimed to evaluate the efficacy and safety of transcranial direct current stimulation (tDCS) in chronic schizophrenia patients with tardive dyskinesia (TD) who were long-term hospitalized. Sixty-four inpatients who met the DSM-IV diagnostic criteria for schizophrenia and TD were randomly assigned to either the active (N=35) or sham (N=29) group. Treatment was given 15 times, with each session lasting for 30 min, and an intensity of 2 mA. The anode was placed on the left dorsolateral prefrontal cortex and the cathode on the right supraorbital region. Primary outcome was measured by the changes in Abnormal Involuntary Movements Scale (AIMS) score. Secondary outcomes were measured using the Positive and Negative Syndrome Scale (PANSS) and the Scale for the Assessment of Negative Symptoms (SANS). Adverse effects of tDCS were assessed with an experimenter-administered open-ended questionnaire throughout the experiment. Of the 64 patients, 52 (81.25%) completed the study. Compared to the sham group, patients in the active group exhibited a significant reduction in both the total AIMS score and the facial-oral subscore (P