Transcranial Direct Current Stimulation (tDCS) Enhances Cognitive Function in Schizophrenia: A Randomized Double-Blind Sham-Controlled Trial

Abstract

This study aimed to examine the cognitive effects of tDCS and the subjective cognitive improvement perceived by patients with schizophrenia. A total of 173 outpatients diagnosed with schizophrenia were recruited for this double-blind, randomized, placebo-controlled trial. Two different stimulation modes were applied: 2 mA 20 minutes active tDCS and sham tDCS. Ten daily sessions over 10 consecutive weekdays were applied, using a bifrontal montage (F3/F4). The Positive and Negative Syndrome Scale for Schizophrenia and the MATRICS Consensus Cognitive Battery (MCCB) were administered at baseline. The MCCB and a scale designed for measuring subjective cognitive improvement were administered to evaluate the outcomes. Post hoc comparisons revealed significant effects between the two types of interventions in Working Memory (EMM difference = 2.716, p < .001) and Neurocognition (EMM difference = 1.289, p = .007. Chi-squared tests demonstrated a significant association between subjective improvement and the treatment group, χ² (2) = 10.413, p = .005, Cramer's V = 0.295. A higher proportion of patients in active tDCS (68.6%) reported cognitive improvement compared to sham tDCS (31.4%). We concluded that tDCS can enhance cognition and generate a satisfactory perception of cognitive improvement in patients with schizophrenia.