High-Frequency Transcranial Random Noise Stimulation for Auditory Hallucinations of Schizophrenia: A Case Series

Transcranial electrical stimulation has been proposed as a noninvasive therapeutic approach for reducing treatment-resistant symptoms of schizophrenia-in particular, auditory hallucinations. However, the high variability observed in the clinical response leaves much room to optimize the stimulation parameters and strengthen its benefits. We proposed to investigate the effects of high-frequency transcranial random noise stimulation (hf-tRNS), which is supposed to induce larger effects than conventional direct current stimulation. Here, we present an initial case series of ten patients with schizophrenia who underwent 10 sessions of 20 min hf-tRNS (2 mA, 100-500 Hz, 1 mA offset), with the anode placed over the left dorsolateral prefrontal cortex and the cathode over the left temporoparietal junction. Patients showed a significant reduction in auditory hallucinations after the hf-tRNS sessions (-36.1 +/- 21.8%, p = 0.0059). In this preliminary, open-label study conducted in ten patients with treatment-resistant symptoms of schizophrenia, frontotemporal hf-tRNS was shown to induce a substantial improvement in auditory hallucinations. Additional sham-controlled studies are needed to further evaluate hf-tRNS as a treatment for schizophrenia.