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Treatment of Auditory Hallucinations with Single-Session tDCS and Cognitive Remediation Training
Perceptual models of auditory verbal hallucinations (AVH) in schizophrenia (Sz) include hyper-excitability of auditory/verbal perception (in left temporoparietal junction; l-TPJ), and hypo-excitability of cognitive control which normally inhibits or reattributes perceptual misrepresentations (in right ventrolateral prefrontal cortex; r-VLPFC). We examined a single-session treatment to enhance cognitive control with Cognitive Remediation Training (CRT) plus anodal tDCS applied to r-VLPFC, and to reduce AVH with cathodal tDCS applied to l-TPJ. Participants were 12 Sz with persistent daily AVH despite stable antipsychotic medication for >2 months. tDCS (2mA, n=7) or sham (0.1mA, n=5) was delivered during CRT. We assessed AVH at baseline and 1-week later. Participants also completed the AX-CPT during electroencephalography (EEG) testing at baseline and immediately after CRT+tDCS. We analyzed beta-band event-related desynchronization (ERD) during the cue evaluation period (200-400ms after ‘A’ stimulus onset) in left central electrodes, which has been linked to cognitive control of attention, and accuracy and RT. AVH was reduced by CRT+tDCS (36% reduction) compared to CRT+sham (18% reduction; d=0.82). In the AX-CPT, RT improvement was greater for CRT+tDCS (ΔRT=73ms) than CRT+sham (ΔRT=21ms; d=0.80). Beta ERD in the evaluation period was increased more for CRT+tDCS (ΔERD=0.49µV2) than CRT+sham (ΔERD=0.00µV2; d=0.89). Accuracy did not change for either group. These preliminary results suggest that a single session of CRT+tDCS may reduce AVH severity and enhance cognitive control in treatment-refractory schizophrenia patients. These findings could lead to a new adjunct biomedical treatment for improving cognition and reducing auditory verbal hallucinations in schizophrenia.