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Effects of Brain Stimulation on 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
🗓️ Study Start (Actual) 22 May 2019
🗓️ Primary Completion (Estimated) 31 December 2023
✅ Study Completion (Estimated) 30 June 2024
👥 Enrollment (Estimated) 120
🔬 Study Type INTERVENTIONAL
📊 Phase NA
Locations:
📍 Sacramento, California, United States

📋 Eligibility Criteria

Description

    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)

    Exclusion Criteria:

    • * 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
Ages Eligible for Study: 18 Years to 50 Years (ADULT)
Sexes Eligible for Study: ALL
Accepts Healthy Volunteers: Yes

🗓️ 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 Registration Dates

  • First Submitted 15 January 2019
  • First Submitted that Met QC Criteria 18 January 2019
  • First Posted 24 January 2019

Study Record Updates

  • Last Update Submitted that Met QC Criteria 15 May 2024
  • Last Update Posted 17 May 2024
  • Last Verified September 2023
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