Effects of Transcranial Direct Current Stimulation (tDCS) on Persistent Auditory Verbal Hallucinations in Schizophrenia

The Neural, Behavioural, and Cognitive Outcomes of Transcranial Direct Current Stimulation (tDCS) for Persistent Auditory Verbal Hallucinations in Schizophrenia

Many individuals with schizophrenia struggle with auditory verbal hallucinations (AVHs). In some cases, these AVHs can be resistant to medication treatment. Previous research has found that transcranial direct current stimulation (tDCS) can be helpful in treating symptoms in individuals with other psychiatric disorders, such as depression. This study will assess if tDCS is effective in treating AVHs in individuals with schizophrenia. tDCS is a non-invasive form of brain stimulation which uses a weak current to temporarily excite or inhibit underlying cortical regions with small electrodes placed on the scalp. tDCS has been found to improve mental processes, including attention and memory function. In addition to examining the effect of tDCS on AVHs, this study will assess the effects of tDCS on mood as well as brain electrical activity with electroencephalogram (EEG) recordings. As an additional component, participants will be invited to participate in neuroimaging. Using magnetic resonance imaging (MRI), brain activity and structure will be examined before and after tDCS. tDCS will be administered twice daily for 5 consecutive days for a total of 10 sessions. These study findings will contribute to the understanding of the impact of tDCS on AVHs, and will also increase knowledge of sound and memory/cognitive processing in individuals with schizophrenia.

Patients - Inclusion Criteria:

• Primary diagnosis of schizophrenia or schizoaffective disorder
• Clinically stable (discretion of psychiatrist)
• Consistent history of AVHs over the course of illness
• >3 AVHs per week
• Positive and Negative Syndrome Scale (PANSS) score of >3
• Primary medications limited to one of the atypical antipsychotics (medications stabilized for 4 weeks prior to enrollment)

Patients - Exclusion Criteria:

• Experiencing an acute psychotic episode
• Current drug/alcohol dependence
• Significant medical illness & mental retardation/learning disability
• Extra-pyramidal symptoms resulting in disordered movement
• Abnormal audiometric assessment (thresholds for pure tones >25 dB)
• History of significant neurological issues & head injuries/concussions resulting in loss of consciousness for >5 minutes

Healthy Controls - Inclusion Criteria:

• In good physical health
• No history of serious mental health issues

Healthy Controls - Exclusion Criteria:

• Personal history of psychiatric disorder
• Family history of schizophrenia in first degree relatives & history of mental health issues in first degree relatives that required extensive treatment or hospitalization
• Current/history of substance abuse
• Significant medical illness
• Extra-pyramidal symptoms resulting in movement disorder
• Abnormal audiometric assessment (thresholds for pure tones >25 dB)
• Significant neurological issues & head injuries/concussions resulting in loss of consciousness for >5 minutes