Effects of Brain Stimulation on Cognition, Oscillations and GABA Levels in Schizophrenia

Study Overview
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Brief Summary
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People with schizophrenia often have problems with attention, learning and memory and other cognitive abilities that interfere with their work and school performance. Unfortunately, even our best treatments often do not significantly reduce these cognitive problems. The current study investigates whether or not delivering a very small electrical current to people's foreheads (called, transcranial direct current stimulation; (tDCS)) might improve functioning in the front part of the brain and reduce these cognitive problems in people with schizophrenia. tDCS is non-invasive and has been shown to improve cognitive functioning in some preliminary studies. The current study will investigate whether giving tDCS during a task is more effective than giving it during rest (Aim 1), whether delivery of tDCS to the front of the head is more effective than delivery to the back of the head (Aim 2), and whether tDCS delivery will alter levels of a major inhibitory neurotransmitter in the brain (GABA; Aim 3) that is important to cognitive functioning and may be disrupted in people with schizophrenia. Although this study is not intended to diagnose, cure or treat schizophrenia or any other disease, if results are positive it will encourage future large-scale studies to determine if tDCS can become an effective treatment for cognitive problems in people with schizophrenia.

Official Title
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Transcranial Direct Current Stimulation (tDCS) Studies of Cognition, Oscillations and GABA Levels in Schizophrenia

Conditions
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Schizophrenia

Intervention / Treatment
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* Device: Transcranial Direct Current Stimulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Participants must be able to sufficiently speak and understand English so as to be able to understand and complete cognitive tasks. All subjects must have the ability to give valid informed consent. Inclusion Criteria for Patients with Schizophrenia Only: Diagnosis of schizophrenia, schizophreniform or schizoaffective disorder No medication changes in the prior month No medication changes anticipated in the upcoming month Stable outpatient or partial hospital status Normal IQ (>70; IQ will be measured by administering the Wechsler Abbreviated Scale of Intelligence (WASI) test) Must not be currently taking the antipsychotic clozapine Exclusion Criteria: Pacemakers Implanted electrical (brain and spinal) stimulators Implanted defibrillator Metallic implants Skin damage or skin conditions such as eczema at the sites where electrodes will be placed Hair styles hindering the placement of electrodes Cranial pathologies Head trauma Epilepsy Mental retardation Any known history of neurological disorders (including epilepsy, amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), stroke, cerebral palsy, any DSM-5 axis I psychiatric disorder (for healthy control subjects), autism) Uncorrected vision problems that would hinder cognitive testing (this also pertains to subjects with color blindness in tasks where discriminating colored objects/items is necessary for successful performance) Pregnancy Substance dependence in the past six months Substance abuse in the past month

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 47 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: DLPFC Stimulation + Task<br>Intervention. 20 minutes of 2 mA direct current stimulation over the dorsolateral prefrontal cortex during cognitive task completion. | Device: Transcranial Direct Current Stimulation<br>* In tDCS, saline-soaked electrodes are temporary affixed to the scalp and connected to a battery-powered current generator. A weak (2 mA) constant current is then briefly applied ( 20 minutes) to stimulate the targeted brain area (e.g. the DLPFC). To control for placebo effects, the study will utilize a sham stimulation protocol that consists of very brief constant stimulation ( 1 minute). Subjects usually cannot discern the difference between the sham and experimental stimulation protocols due to habituation.<br>|
| Experimental: DLPFC Stimulation + Rest<br>Intervention. 20 minutes of 2 mA direct current stimulation over the dorsolateral prefrontal cortex during rest. | Device: Transcranial Direct Current Stimulation<br>* In tDCS, saline-soaked electrodes are temporary affixed to the scalp and connected to a battery-powered current generator. A weak (2 mA) constant current is then briefly applied ( 20 minutes) to stimulate the targeted brain area (e.g. the DLPFC). To control for placebo effects, the study will utilize a sham stimulation protocol that consists of very brief constant stimulation ( 1 minute). Subjects usually cannot discern the difference between the sham and experimental stimulation protocols due to habituation.<br>|
| Sham Comparator: Sham Stimulation + Task<br>Placebo Comparator. 0.5-1 minutes of 2 mA direct current stimulation over dorsolateral prefrontal cortex followed by 19-19.5 minutes of sham stimulation, during cognitive task completion. | Device: Transcranial Direct Current Stimulation<br>* In tDCS, saline-soaked electrodes are temporary affixed to the scalp and connected to a battery-powered current generator. A weak (2 mA) constant current is then briefly applied ( 20 minutes) to stimulate the targeted brain area (e.g. the DLPFC). To control for placebo effects, the study will utilize a sham stimulation protocol that consists of very brief constant stimulation ( 1 minute). Subjects usually cannot discern the difference between the sham and experimental stimulation protocols due to habituation.<br>|
| Sham Comparator: Sham Stimulation + Rest<br>Placebo Comparator. 0.5-1 minutes of 2 mA direct current stimulation over dorsolateral prefrontal cortex followed by 19-19.5 minutes of sham stimulation, during rest. | Device: Transcranial Direct Current Stimulation<br>* In tDCS, saline-soaked electrodes are temporary affixed to the scalp and connected to a battery-powered current generator. A weak (2 mA) constant current is then briefly applied ( 20 minutes) to stimulate the targeted brain area (e.g. the DLPFC). To control for placebo effects, the study will utilize a sham stimulation protocol that consists of very brief constant stimulation ( 1 minute). Subjects usually cannot discern the difference between the sham and experimental stimulation protocols due to habituation.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| EEG Correlates of Language and Cognitive Control | Electrophysiological data recorded during completion of cognitive control tasks. We will measure oscillatory activity from 3-80 Hz. | Assessment will begin immediately following stimulation and last for about 1.5 hours. | 
| Behavioral Response | We will assess performance on the Dot Pattern Expectancy (DPX) task (error rates). | Assessment will begin immediately following stimulation and last for about 1.5 hours. | 
| Behavioral Response | We will assess performance on the Dot Pattern Expectancy (DPX) task (d-prime scores). | Assessment will begin immediately following stimulation and last for about 1.5 hours. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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schizophrenia, EEG, tDCS, dorsolateral prefrontal cortex, cognitive control, transcranial direct current stimulation, GABA, MR spectroscopy