SchizophreniaNCT03814967
Effects of Brain Stimulation on Higher-Order Cognition
A study testing Transcranial Direct Current Stimulation in people with Schizophrenia, run by University of California, Davis at 1 site in United States.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 to 50 yearsHealthy volunteers can take part
- Conditions the study is for
- Schizophrenia
- What is being tested?
- Transcranial Direct Current Stimulation
- Type of treatment
- Medical device
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 86 participants
- Where
- 1 siteUnited States
- Study dates
- 22 May 2019to 31 May 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 50 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- 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.
- 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)
Who cannot join
- 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
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- 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 locations and contacts
1 site in 1 country.
United States1 site
Imaging Research Center
Sacramento, California, 95817
About this study
Official title: Transcranial Direct Current Stimulation (tDCS) Studies of Behavioral and Electrophysiological (EEG) Correlates of Higher-Order Cognition
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.
- Conditions
- Schizophrenia
- Being tested
- Transcranial Direct Current Stimulation
- Keywords
- schizophrenia, EEG, tDCS, dorsolateral prefrontal cortex, cognitive control, language, transcranial direct current stimulation
- Medical subject headings
- Schizophrenia, Language
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Transcranial Direct Current StimulationDevice
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.
| Study group | Role | What they receive |
|---|---|---|
| DLPFC Stimulation | Experimental | Intervention. 20 minutes of 2 mA direct current stimulation over the dorsolateral prefrontal cortex. Receives: Device: Transcranial Direct Current Stimulation |
| Occipital Stimulation | Active comparator | Intervention. 20 minutes of 2 mA direct current stimulation over the occipital cortex. Receives: Device: Transcranial Direct Current Stimulation |
| Sham Stimulation | Sham comparator | 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 Receives: Device: Transcranial Direct Current Stimulation |
What is being measured
The primary outcome is the main question the study is designed to answer.
EEG Correlates of Language and Cognitive Control
Electrophysiological data recorded during completion of cognitive control and language comprehension tasks. We will measure oscillatory activity in the theta, alpha, beta and gamma frequency bands.
Measured: Assessment will begin immediately following stimulation and last for about 1.5 hours.
Behavioral Response (Cognitive Control Task)
We will assess performance on the Dot Pattern Expectancy (DPX) task (error rates and d-prime scores).
Measured: Assessment will begin immediately following stimulation and last for about 1.5 hours.
Behavioral Response (Language Task)
We will assess performance on a novel Language Comprehension task (accuracy and semantic relatedness judgement scores).
Measured: Assessment will begin immediately following stimulation and last for about 1.5 hours.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted24 Jan 2019
- Study start22 May 2019
- Primary completion31 May 2025
- Study completion31 May 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for SchizophreniaStudies of the same condition, open and under way.
- More trials run by University of California, DavisThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 86 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of California, Davis
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03814967
- Sponsor's protocol ID
- 1344169
- Other IDs
- UCD#3565
- Status last verified
- Jul 2025
- First submitted
- 15 Jan 2019
- Last updated
- 29 Jul 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- Yes
- Individual data sharing
- Yes: Select data from this study may be submitted to the National Institute of Mental Health Data Archive (NDA). NDA is a data repository run by the National Institute of Mental Health (NIMH) that allows researchers studying mental illness to collect and share de-identified information with each other. The data repository is accessible only to qualified investigators. All subject data will be de-identified (subject names will not be used) and each subject will have a separate identifier called a Global Unique Identifier (GUID) to remove any possibility that "the identities of the subjects cannot be readily ascertained or otherwise associated with the data by the repository staff or secondary data users." (45 CFR, 46.102).
Study at a glance
From the registry record, last updated by the sponsor on 29 Jul 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Transcranial Direct Current Stimulation (tDCS) Studies of Behavioral and Electrophysiological (EEG) Correlates of Higher-Order Cognition
- ClinicalTrials.gov ID
- NCT03814967
- Acronym / sponsor ID
- 1344169
- Conditions
- Schizophrenia
- Keywords
- schizophrenia, EEG, tDCS, dorsolateral prefrontal cortex, cognitive control, language, transcranial direct current stimulation
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 86 participants (actual)
- Lead sponsor
- University of California, DavisUniversity, hospital or other
- Study start
- 22 May 2019 (actual)
- Primary completion
- 31 May 2025 (actual)
- Study completion
- 31 May 2025 (actual)
- First posted
- 24 Jan 2019 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (participant, investigator)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| DLPFC Stimulation | Experimental | Device: Transcranial Direct Current StimulationIntervention. 20 minutes of 2 mA direct current stimulation over the dorsolateral prefrontal cortex. |
| Occipital Stimulation | Active comparator | Device: Transcranial Direct Current StimulationIntervention. 20 minutes of 2 mA direct current stimulation over the occipital cortex. |
| Sham Stimulation | Sham comparator | Device: Transcranial Direct Current StimulationPlacebo 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 |
Who may qualify
- Ages
- 18 to 50 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (7 listed)
- 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.
- Diagnosis of schizophrenia, schizophreniform or schizoaffective disorder
- No medication changes in the prior month
- No medication changes anticipated in the upcoming month
Key exclusion criteria (15 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Transcranial Direct Current StimulationIn 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. | Device | DLPFC Stimulation, Occipital Stimulation, Sham Stimulation |
Primary outcome
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 and language comprehension tasks. We will measure oscillatory activity in the theta, alpha, beta and gamma frequency bands.
Behavioral Response (Cognitive Control Task)
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 and d-prime scores).
Behavioral Response (Language Task)
Time frame: Assessment will begin immediately following stimulation and last for about 1.5 hours.
We will assess performance on a novel Language Comprehension task (accuracy and semantic relatedness judgement scores).
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 29 Jul 2025.
- Learn more or sign up for the study here!Link provided by the sponsor.
- Individual participant dataSharing planned: Yes. Select data from this study may be submitted to the National Institute of Mental Health Data Archive (NDA). NDA is a data repository run by the National Institute of Mental Health (NIMH) that allows researchers studying mental illness to collect and share de-identified information with each other. The data repository is accessible only to qualified investigators. All subject data will be de-identified (subject names will not be used) and each subject will have a separate identifier called a Global Unique Identifier (GUID) to remove any possibility that "the identities of the subjects cannot be readily ascertained or otherwise associated with the data by the repository staff or secondary data users." (45 CFR, 46.102).
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Transcranial Direct Current Stimulation in people with Schizophrenia, run by University of California, Davis at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 7 inclusion and 15 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 29 Jul 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
EEG Correlates of Language and Cognitive Control (time frame: Assessment will begin immediately following stimulation and last for about 1.5 hours.). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 29 Jul 2025.