Study Stopped
Per request of the study PI (fyi: NOT due to adverse events).
The Effects of tDCS on the Neuronal Mechanisms of Cognitive Control in Schizophrenia
The Effects of Transcranial Direct Current Stimulation on the Neuronal Mechanisms of Cognitive Control in Schizophrenia
1 other identifier
interventional
6
1 country
1
Brief Summary
The purpose of this study is to better understand the neural correlates of cognitive control (CC) deficits in schizophrenia and determine how these mechanisms can be modulated by transcranial direct current stimulation (tDCS). CC is a critical neurocognitive process that is required for flexible, directed thought and action based on goals and intentions. Identifying and developing paradigms to improve CC is therefore a mental health priority. Current theories of CC postulate that recruitment of the dorsolateral prefrontal cortex (DLPFC) is essential for this process by maintaining high-level information that it can then use to orchestrate patterns of activation in other brain networks to support optimal performance. tDCS is a safe, noninvasive method of modulating regional brain excitability via brief (15-20 m) application of a weak (1-2 mA) current. The goal of the proposed experiments is to combine tDCS with functional magnetic resonance imaging (fMRI) to test the hypotheses that 1) acute tDCS over the DLPFC can improve performance during a CC task (the dot pattern expectancy (DPX) variant of the AX-Continuous Performance Task) in schizophrenia patients and healthy control subjects, and 2) acute tDCS over the DLPFC can increase recruitment of the DLPFC during the DPX. Effects of tDCS on brain functional connectivity (during CC as well as during the resting state) will also be examined, as well as effects on an episodic memory task. The current study will be the first to use functional magnetic resonance imaging (fMRI) to examine the effects of tDCS on the neuronal mechanisms of CC in schizophrenia, and has potentially important implications for therapeutic development for this treatment refractory yet disabling aspect of the illness.
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at below P25 for not_applicable schizophrenia
Started Apr 2017
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
March 1, 2017
CompletedFirst Posted
Study publicly available on registry
March 10, 2017
CompletedStudy Start
First participant enrolled
April 1, 2017
CompletedPrimary Completion
Last participant's last visit for primary outcome
February 23, 2023
CompletedStudy Completion
Last participant's last visit for all outcomes
February 23, 2023
CompletedResults Posted
Study results publicly available
June 13, 2024
CompletedJune 13, 2024
October 1, 2023
5.9 years
March 1, 2017
March 26, 2024
May 18, 2024
Conditions
Keywords
Outcome Measures
Primary Outcomes (2)
Dorsolateral Prefrontal Cortex Response
Blood oxygen level-dependent response of the dorsolateral prefrontal cortex during a cognitive control task (Dot-Probe Expectancy Task)
Assessment will begin immediately following stimulation and last for up to an hour.
Behavioral Response
Cognitive control-related performance (d-prime context) associated with the task (Dot-Probe Expectancy Task). The d-prime context index was calculated by computing a d-prime index from hits on AX trials and false alarms on BX trials as Z(H) - Z(F), with H representing hits on AX trials, F representing false alarms on BX trials, and Z representing the z-transform of a value. Positive d-prime values indicate more cognitive control, and negative values indicate less cognitive control.
Assessment will begin immediately following stimulation and last for up to an hour.
Study Arms (2)
Sham Followed by Experimental Stimulation
OTHERSham stimulation administered followed by 24-48 hour washout, then experimental stimulation. Experimental Intervention. 20 minutes of 2 mA direct current stimulation over the dorsolateral prefrontal cortex Placebo Comparator. 1 minute of 2 mA direct current stimulation over the dorsolateral prefrontal cortex followed by 19 minutes of sham stimulation.
Experimental Stimulation Followed by Sham
OTHERExperimental stimulation administered followed by 24-48 hour washout, then sham stimulation. Experimental Intervention. 20 minutes of 2 mA direct current stimulation over the dorsolateral prefrontal cortex Placebo Comparator. 1 minute of 2 mA direct current stimulation over the dorsolateral prefrontal cortex followed by 19 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:
- Sufficient English literacy so as to be able to understand and complete cognitive tasks.
- The ability to give valid informed consent.
- Diagnosis of schizophrenia, schizophreniform or schizoaffective disorder (for patient group)
- Stable outpatient or partial hospital status (for patient group)
You may not qualify if:
- Psychiatric medication changes in the prior month (for patient group)
- No psychiatric medication changes anticipated in the upcoming month (for patient group)
- Intelligence Quotient (IQ) \< 70; IQ will be measured by administering the Wechsler Abbreviated Scale of Intelligence (WASI) test.
- People under the age of 18
- Pregnant Women
- Prisoners
- Pacemakers
- Implanted brain stimulators
- Implanted defibrillator
- Metallic implants
- Skin damage or skin conditions such as eczema at the sites where electrodes will be placed
- Dreadlocks or other hair styles hindering the placement of tDCS electrodes
- Cranial pathologies
- Head trauma
- Epilepsy
- +4 more criteria
Contact the study team to confirm eligibility.
Sponsors & Collaborators
Study Sites (1)
Imaging Research Center, University of California Davis Medical Center
Sacramento, California, 95817, United States
MeSH Terms
Conditions
Interventions
Condition Hierarchy (Ancestors)
Intervention Hierarchy (Ancestors)
Results Point of Contact
- Title
- Tiffany T . Norris
- Organization
- University of CA Davis Health
Study Officials
- STUDY DIRECTOR
Cameron Carter, M.D.
University of California, Davis
Publication Agreements
- PI is Sponsor Employee
- Yes
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
March 1, 2017
First Posted
March 10, 2017
Study Start
April 1, 2017
Primary Completion
February 23, 2023
Study Completion
February 23, 2023
Last Updated
June 13, 2024
Results First Posted
June 13, 2024
Record last verified: 2023-10
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 Code of Federal Regulations, 46.102).