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

University of Ottawa84 enrolled

Overview

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.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Enrollment

Conditions

Auditory Hallucination, Verbal

Eligibility

Sex: ALLMin age: 18 YearsMax age: 65 YearsHealthy volunteers:

Medical Language ↔ Plain English

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

Outcomes

Primary Outcomes

Change in auditory hallucination severity measured by the Psychotic Symptom Rating Scale (PSYRATS)

The PSYRATS is a multidimensional measure of auditory hallucinations, including 11 items rated on five-point (0-4) scales (total score range 0-44). Symptoms are rated over the last week, with higher scores reflecting more severe symptoms. The dimensions assessed are frequency, duration, location, loudness, beliefs about origin, negative content, intensity of negative content, amount of distress, intensity of distress, disruption of life and control.

Time frame: Baseline, after 2nd tDCS session on days 1, 3, and 5, and follow-up (within a week of completing tDCS)

Secondary Outcomes

Change in Voice Power Differential Scale (VPDS) Scores

The Voice Power Differential Scale (VPDS) is a 7-item scale used to measure the perceived power differences between the voice and the voice hearer. Each item is rated on a five-point scale (1-5), with higher scores indicating greater power differential in favour of the voices, with total scores ranging from 7-35.