Effects of Brain Stimulation on Higher-Order Cognition

University of California (UC) Davis

Status: Completed

Conditions: Schizophrenia

Treatments: Device: Transcranial Direct Current Stimulation

Study type: Interventional

Funder types: Other

Identifiers

NCT03814967

UCD#3565 (Other Identifier)

1344169

Details and patient eligibility

About

The purpose of this study is to better understand the neural correlates of higher-order cognition, both in the healthy brain and in schizophrenia, and to determine how these mechanisms are modulated by transcranial direct current stimulation (tDCS) at frontal and occipital scalp sites. Testing the effects of tDCS at these scalp sites on cognitive task performance will help us understand the roles of the brain regions corresponding to these sites during higher-order cognitive processing (language comprehension, cognitive control, and related attention and memory processes). Behavioral and electrophysiological (EEG) measures will be used to assess cognitive performance. The investigator's overarching hypothesis is that stimulating prefrontal circuits with tDCS can improve cognitive control performance, and ultimately performance on a range of cognitive tasks, as compared to stimulating a different cortical region (occipital cortex) or using sham stimulation. This study is solely intended as basic research in order to understand brain function in healthy individuals and individuals with schizophrenia. This study is not intended to diagnose, cure or treat schizophrenia or any other disease.

Enrollment: 86 patients

Sex: All

Ages: 18 to 50 years old

Volunteers: Accepts Healthy Volunteers

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)

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

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Double Blind

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86 participants in 3 patient groups

DLPFC Stimulation

Experimental group

Description:

Intervention. 20 minutes of 2 mA direct current stimulation over the dorsolateral prefrontal cortex.

Treatment:

Device: Transcranial Direct Current Stimulation

Occipital Stimulation

Active Comparator group

Description:

Intervention. 20 minutes of 2 mA direct current stimulation over the occipital cortex.

Treatment:

Device: Transcranial Direct Current Stimulation

Sham Stimulation

Sham Comparator group

Description:

Placebo Comparator. 0.5-1 minutes of 2 mA direct current stimulation over the dorsolateral prefrontal cortex followed by 19-19.5 minutes of sham stimulation

Treatment:

Device: Transcranial Direct Current Stimulation