The Effects of tDCS on the Neuronal Mechanisms of Cognitive Control in Schizophrenia

May 18, 2024 updated by: University of California, Davis

The Effects of Transcranial Direct Current Stimulation on the Neuronal Mechanisms of Cognitive Control in Schizophrenia

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.

Study Overview

Status

Terminated

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

6

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • California
      • Sacramento, California, United States, 95817
        • Imaging Research Center, University of California Davis Medical Center

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 35 years (Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria

  • 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)

Exclusion Criteria

  • 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
  • Mental retardation
  • Neurological disorders
  • 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).
  • Other than nicotine, no subjects reporting substance dependence in the past six months and no substance abuse in the past month

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Other: Sham Followed by Experimental Stimulation

Sham 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.
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.
Other Names:
  • tDCS
Other: Experimental Stimulation Followed by Sham

Experimental 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.
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.
Other Names:
  • tDCS

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Dorsolateral Prefrontal Cortex Response
Time Frame: Assessment will begin immediately following stimulation and last for up to an hour.
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
Time Frame: Assessment will begin immediately following stimulation and last for up to an hour.

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.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of California, Davis

Investigators

  • Study Director: Cameron Carter, M.D., University of California, Davis

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

April 1, 2017

Primary Completion (Actual)

February 23, 2023

Study Completion (Actual)

February 23, 2023

Study Registration Dates

First Submitted

March 1, 2017

First Submitted That Met QC Criteria

March 6, 2017

First Posted (Actual)

March 10, 2017

Study Record Updates

Last Update Posted (Actual)

June 13, 2024

Last Update Submitted That Met QC Criteria

May 18, 2024

Last Verified

October 1, 2023

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 1016455

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

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).

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

Yes

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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