Clinical trial NCT03814967: Effects of Brain Stimulation on Higher-Order Cognition
Official title: Transcranial Direct Current Stimulation (tDCS) Studies of Behavioral and Electrophysiological (EEG) Correlates of Higher-Order Cognition
Study type: INTERVENTIONAL
Overall status: ACTIVE_NOT_RECRUITING
Phase: NA
Conditions: Schizophrenia
Keywords: schizophrenia
EEG
tDCS
dorsolateral prefrontal cortex
cognitive control
language
transcranial direct current stimulation
Lead sponsor: University of California, Davis
Sponsor class: OTHER
First posted: 2019-01-24
Enrollment: 120
Sex: ALL
Minimum age (years): 18
Maximum age (years): 50
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: BASIC_SCIENCE

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.


Eligibility criteria: 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

Primary outcomes:
measure: EEG Correlates of Language and Cognitive Control
timeFrame: Assessment will begin immediately following stimulation and last for about 1.5 hours.
measure: Behavioral Response (Cognitive Control Task)
timeFrame: Assessment will begin immediately following stimulation and last for about 1.5 hours.
measure: Behavioral Response (Language Task)
timeFrame: Assessment will begin immediately following stimulation and last for about 1.5 hours.
Secondary outcomes:
Other outcomes:
Locations:
city: Sacramento
country: United States
facility: Imaging Research Center
state: California
Study officials:
References: