RCT of tDCS Combined With Cognitive Training in Schizophrenia

tDCS was applied using the StarStim 8 (NeuroElectrics, Barcelona, Spain). tDCS with strength of two milliamps for 20 minutes was applied based on montage recommended (Hoy et al., 2014). The stimulation electrode was applied according to international EEG system 10-20. The anode was applied at the left dorsolateral prefrontal cortexDLPFC, which was located at F3; the cathode was applied at the right dorsolateral prefrontal cortexDLPFC, which was located at F4. In the tDCS group, the participants received 'ramp-up' of 30 seconds, followed by active stimulation with a steady current of two milliamps for 20 minutes, then 'ramp-down' of 30 seconds. In the sham group, the current was only delivered in the 30-second 'ramp-up' and 30-second 'ramp-down' period.

All participants received the same program of cognitive training in the app 'the Peak' on a hand-held portable iPad (https://www.peak.net/science/). The traditional Chinese version with Cantonese instructions was selected. The progress, the errors, and the sum scores were stored in the personal profile for interactive feedback on adjusting the difficulty level. The participants performed the tasks in pseudorandomized order during each session. Each training session lasted for 20 minutes, concurrent with either active or sham tDCS stimulation.