TDCS for Auditory Hallucinations in Schizophrenia

Overview

The purpose of the present research is to test a potential new treatment for auditory verbal hallucinations in schizophrenia that uses transcranial Direct Current Stimulation (tDCS), a neurostimulation technique that passes an extremely weak electric current through the brain. During the treatment, two electrodes are positioned on the scalp above regions of the brain implicated in abnormal cortical activity associated with auditory verbal hallucinations in schizophrenia. Due to the directional flow of current, one electrode, termed "cathodal",inhibits cortical activity, and the other, termed "anodal", increases cortical activity. These electrodes will be placed such that cathodal stimulation is applied to an area associated with hyperactivity and anodal stimulation to an area associated with hypoactivity. One preliminary study has revealed that this form of neurostimulation can alleviate auditory verbal hallucination symptoms both immediately following five days of treatment and up to three months after the final treatment. The goal of this study is to replicate these effects and explore the mechanisms that may underpin them.

90 patients with persistent auditory verbal hallucinations will be recruited to this study. Each individual will participate in behavioral assessments lasting up to 3 hours each and will then be randomized to receive a series of active vs. sham tDCS treatments. For active treatment, patients will have the inhibitory (cathodal) tDCS electrode placed over left auditory cortex relative to an anodal placed over frontal cortex on the right side. tDCS treatments will take place for 20 min per day for 5 consecutive days. For sham, procedures will be similar except that sham (inactive) tDCS treatment will be used. Assessment batteries will then be repeated following completion of treatment and at 1 and 3 mo following treatment. In addition, patients will be offered the possibility to participate in a concurrent magnetic resonance imaging (MRI) study aimed at evaluating the effects of tDCS on activation of auditory cortex during an auditory discrimination task as well as on other imaging parameters related to resting brain activity and metabolism. Patients who agree to participate in this MRI study will be scanned before and after active or sham tDCS. In addition, 5-15 schizophrenia patients will complete a week of High-density, e.g., "high-definition" tDCS (HD-tDCS) open label. In addition to hallucinating patients, we will recruit up to 20 healthy controls and 20 non-hallucinating patients, who will have similar assessments to the patients, but will not receive tDCS. Overall, the investigators hypothesize that tDCS treatment will lead to reduction in hallucinations, improvement in auditory function, and change in EEG and MRI measurements so that patients more closely resemble healthy volunteers and non-hallucinating patients.