The effect of bilateral high-definition γ-tACS on negative symptoms and mismatch negativity in schizophrenia

At present, there is a lack of good treatment methods for the negative symptoms of schizophrenia. Previous studies have suggested that high-definition transcranial alternating current stimulation (HD tACS) in the dorsolateral prefrontal cortex (DLPFC) can significantly improve negative symptoms and that γ oscillation may also be effective for treating negative symptoms. The aim of our study was to investigate the therapeutic effect of HD γ-tACS on the negative symptoms of schizophrenia. Active auditory mismatch negativity (MMN) was introduced as neurobiological evidence to verify the intervention effect of tACS on schizophrenia.

A total of 53 patients with schizophrenia mainly with negative symptoms were enrolled in our study. Twenty-seven patients were divided into a real group, which was based on 60 Hz stimulation, 15 min on the unilateral side, for 10 consecutive working days, and 26 patients were divided into a sham group to receive tACS intervention. At baseline and after the intervention, the clinical and behavior scale measurements and EEG data collection under the active auditory oddball paradigm were performed in the two groups, and the differences between the two groups were compared and analysed.

1. At baseline, there was no significant difference in the active MMN (MMN/P3a complex) amplitude between the two groups. 2. After tACS intervention, the active MMN amplitudes of the Fz, FCz, Cz, CPz and Pz channels in the central frontoparietal lobe of the real tACS group increased significantly. 3. Negative symptoms were significantly reduced in the real tACS group positive and negative syndrome scale (PANSS) negative symptom subscale score. 4. Regression analysis revealed that in the Fz channel, the change in MMN was moderately positively correlated with the reduction in negative symptom scores.

γ-tACS in the bilateral dlPFC can significantly improve the negative symptoms of patients with schizophrenia, and the amplitude of active MMN in the frontoparietal region is significantly increased after intervention. To some extent, the greater the improvement in active MMN after intervention compared with baseline, the more obvious the improvement in clinical negative symptoms. This study provides a reference for tACS therapy to improve negative symptoms in patients with schizophrenia.