Effects of Brain Stimulation on Higher-Order Cognition
Transcranial Direct Current Stimulation (tDCS) Studies of Behavioral and Electrophysiological (EEG) Correlates of Higher-Order Cognition
2 other identifiers
interventional
86
1 country
1
Brief 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. 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.
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at P50-P75 for not_applicable schizophrenia
Started May 2019
Longer than P75 for not_applicable schizophrenia
1 active site
Health score is calculated from publicly available data and should be used for screening purposes only.
Trial Relationships
Click on a node to explore related trials.
Study Timeline
Key milestones and dates
First Submitted
Initial submission to the registry
January 15, 2019
CompletedFirst Posted
Study publicly available on registry
January 24, 2019
CompletedStudy Start
First participant enrolled
May 22, 2019
CompletedPrimary Completion
Last participant's last visit for primary outcome
May 31, 2025
CompletedStudy Completion
Last participant's last visit for all outcomes
May 31, 2025
CompletedJuly 29, 2025
July 1, 2025
6 years
January 15, 2019
July 24, 2025
Conditions
Keywords
Outcome Measures
Primary Outcomes (3)
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.
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).
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).
Assessment will begin immediately following stimulation and last for about 1.5 hours.
Study Arms (3)
DLPFC Stimulation
EXPERIMENTALIntervention. 20 minutes of 2 mA direct current stimulation over the dorsolateral prefrontal cortex.
Occipital Stimulation
ACTIVE COMPARATORIntervention. 20 minutes of 2 mA direct current stimulation over the occipital cortex.
Sham Stimulation
SHAM COMPARATORPlacebo 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
Interventions
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.
Eligibility Criteria
You may qualify if:
- 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)
You may not qualify if:
- 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
Contact the study team to confirm eligibility.
Sponsors & Collaborators
Study Sites (1)
Imaging Research Center
Sacramento, California, 95817, United States
Related Links
MeSH Terms
Conditions
Interventions
Condition Hierarchy (Ancestors)
Intervention Hierarchy (Ancestors)
Study Design
- Study Type
- interventional
- Phase
- not applicable
- Allocation
- RANDOMIZED
- Masking
- DOUBLE
- Who Masked
- PARTICIPANT, INVESTIGATOR
- Purpose
- BASIC SCIENCE
- Intervention Model
- CROSSOVER
- Sponsor Type
- OTHER
- Responsible Party
- SPONSOR
Study Record Dates
First Submitted
January 15, 2019
First Posted
January 24, 2019
Study Start
May 22, 2019
Primary Completion
May 31, 2025
Study Completion
May 31, 2025
Last Updated
July 29, 2025
Record last verified: 2025-07
Data Sharing
- IPD Sharing
- Will share
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).