NCT04267003 · University of California, Davis
Effects of Brain Stimulation on Cognition, Oscillations and GABA Levels in Schizophrenia
What this study is about
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.
View original scientific description
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.
Interventions
DEVICE
Transcranial Direct Current Stimulation
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.
Primary outcome measures
EEG Correlates of Language and Cognitive Control
Time frame: Assessment will begin immediately following stimulation and last for about 1.5 hours.
Electrophysiological data recorded during completion of cognitive control tasks. We will measure oscillatory activity from 3-80 Hz.
Behavioral Response
Time frame: Assessment will begin immediately following stimulation and last for about 1.5 hours.
We will assess performance on the Dot Pattern Expectancy (DPX) task (error rates).
Behavioral Response
Time frame: Assessment will begin immediately following stimulation and last for about 1.5 hours.
We will assess performance on the Dot Pattern Expectancy (DPX) task (d-prime scores).
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
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
- 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
- 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)
- Substance dependence in the past six months
- Substance abuse in the past month
Where
- Sacramento, California
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Mar 30, 2026 · Source of record for eligibility and locations