Transcranial direct current stimulation for refractory auditory hallucinations in schizophrenia: Acute and 16-week outcomes

Background: Transcranial direct current stimulation (tDCS) has demonstrated efficacy against antipsychotic-refractory auditory verbal hallucinations (AVH) in schizophrenia. The duration of persistence of benefit is not well characterized.

Materials and methods: Thirty-one adults with schizophrenia and medication-refractory AVH were treated with 2-3 mA tDCS in 30 min sessions, twice a day, 6 days a week, for 2-4 weeks. The anode was sited over F3 and the cathode midway between T3 and P3 in the 10-20 EEG system. Patients were assessed until a 4-month study endpoint using two auditory hallucination rating scales and the Positive and Negative Syndrome Scale (PANSS-N).

Results: Auditory hallucinations were moderately reduced by tDCS with 25%-29% improvement evident by the end of the 2^nd week and another 10% improvement between week 2 and 4 months. There was no loss of benefit at the end of the 4-month study. There was also a small (11%) but statistically significant improvement in PANSS-N scores.

Conclusions: Although this study is limited by the nonblind, uncontrolled design, the results suggest that tDCS, as delivered, holds promise for treating refractory AVH in schizophrenia; the benefits persist beyond the short term.