Non-Invasive Direct Current Stimulation for Cognition in Schizophrenia

Study Overview
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Brief Summary
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This study proposes to assess the effect of trans-cranial direct current stimulation (tDCS) on cognitive control, working memory, functional, clinical, and cognitive outcomes in schizophrenia patients.

Detailed Description
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Cognitive functions and EEG correlates will be thoroughly assessed in schizophrenia patients undergoing a tDCS treatment and compared with patients receiving a placebo stimulation. The treatment will involve 20 minutes of tDCS application to the left prefrontal and temporo-parietal cortex, twice a day for five days, a procedure shown to be effective in improving other symptoms of psychosis such as negative symptoms and hallucinations. Critically, in addition to standard neuropsychological testing, cognitive assessments will involve tasks that tap cognitive control and working memory, impairments in which comprise two of the core cognitive disturbances in schizophrenia and which have been linked to brain rhythm disturbances measurable by EEG recordings. Investigators will also assess changes in functional outcome by tDCS and investigate relationships between improvements in cognition, brain rhythms and functional outcome. All these assessments will occur just prior to tDCS application, just after completion of the tDCS series, and then again at 2 months follow-up. There will be two separate independent groups of patients who will be randomized to active versus sham treatments. The first group will have early course schizophrenia (less than 5 years of antipsychotic treatment; n=40). The second group will be chronic schizophrenia (greater than 5 years of antipsychotic treatment; n=40). Relevance This proposal would be the first integrated study of the effects of tDCS on cognitive symptoms, brain function and functional outcome in schizophrenia. A positive outcome would represent a marked improvement in clinical therapeutics for cognition in psychosis and provide a powerful tool for improving functional outcome in this debilitating disorder. Understanding the impact on brain rhythm disturbances could support the study of similar stimulation-based therapeutic approaches to other neuropsychiatric disorders that shows similar disturbances in cognition and brain rhythms activity, such as bipolar disorder and autism.

Official Title
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Non-Invasive Direct Current Stimulation for Cognition in Schizophrenia

Conditions
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Schizophrenia, Psychosis

Intervention / Treatment
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* Device: Active Trans-cranial direct-current stimulation
* Device: Sham Trans-cranial direct current stimulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Early course psychosis: DSM-V diagnosis of Schizophrenia, Schizoaffective disorder, or schizophreniform disorder. ages 18-50 years on stable doses of medication for at least one month not taking benzodiazepines or mood stabilizers. Mild to severe cognitive impairment in MATRICS Consensus Cognitive Battery (composite scores < 40) Chronic psychosis: Same as early course psychosis but >5 years of antipsychotic treatment Exclusion Criteria: Diagnostic and Statistical Manual-Version V (DSM-V) diagnosis of mental retardation significant head injury medical illness affecting brain function or structure pregnancy or postpartum (<6 weeks after delivery or miscarriage) significant neurologic disorder (e.g seizure disorder) inability to provide informed consent significant color blindness that affects task performance Comorbidity for DSM-V substance abuse disorder within the past one month Temporal relation between illness onset and head injury Taking benzodiazepines or mood stabilizers (lithium allowed) Positive drug screen (excluding THC at baseline)

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Active Stimulation<br>Active stimulation group will receive 20 min of 2 mA direct current stimulation. | Device: Active Trans-cranial direct-current stimulation<br>* Active stimulation group will receive 20 min of 2 mA direct current stimulation.<br>* Other names: tDCS;|
| Sham Comparator: Sham Stimulation<br>This will be an active sham involving brief (15 msec) low current (0.11 mA) pulses every 550 ms. | Device: Sham Trans-cranial direct current stimulation<br>* This will be an active sham involving brief (15 msec) low current (0.11 mA) pulses every 550 ms.<br>* Other names: tDCS;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cognitive Control | The investigators will assess cognitive control using the Preparing to Overcome Prepotency (POP) task. The accuracy mean differences between the high and low control conditions will be used as dependent measures. The study is powered at 0.8 to observe a post-pre treatment improvement in cognitive control with a substantial effect size (d=0.56) compared to sham stimulation with effects relatively stable measured 2 months after baseline. The hypothesized effect size will be d=0.60. | Week 1 | 
| Working Memory | The investigators will assess working memory using a working memory task. The accuracy mean differences between the high and low control conditions will be used as dependent measures. The study is powered at 0.8 to observe a post-pre treatment improvement in cognitive control with a substantial effect size (d=0.56) compared to sham stimulation with effects relatively stable measured 2 months after baseline. The hypothesized effect size will be d=0.60. | Week 1 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Negative Symptoms | A secondary outcome measure is the severity of negative symptoms as quantified by Scale for the Assessment of Negative Symptoms (SANS). This study is powered at 0.8 to observe a post-pre treatment improvement in negative symptoms with a moderate effect size (d=0.56) compared to sham stimulation with effects relatively stable measured 2 months after baseline. The hypothesized effect size will be d=0.60. | Week 1 | 
| Auditory Hallucinations | A secondary outcome measure is the change over time in the severity of auditory hallucinations as assessed by the Auditory Hallucination Rating Scale (AHRS). In a study conducted using a similar montage and current strength (Brunelin et. al 2012), a reduction in auditory hallucinations with a substantial effect size (d=1.58) was observed in 30 patients with schizophrenia. However, as their study recruited only those patients with severe hallucinations while the current study does not have such an inclusion criterion. The investigators expect a more modest effect size of d=0.60. | Week 1 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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tDCS, cognitive control, working memory, EEG, gamma oscillations