Transcranial Direct and Alternating Stimulation of the Prefrontal Cortex for Cognitive Improvement in Schizophrenia

Study Overview
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Brief Summary
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The purpose of this study is to investigate different stimulation intensities and frequencies of transcranial direct and alternating current stimulation over the dorsolateral prefrontal cortex for cognitive improvement in schizophrenia.

Detailed Description
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In this randomized, double-blind study, 50 patients diagnosed with schizophrenia are randomly assigned into two arms. The first group receives transcranial direct current stimulation (tDCS) at three intensities (2 mA, 3 mA, and sham) and the second group receives transcranial alternating current stimulation (tACS) at three different frequencies (8 Hz, 40 Hz, and sham) over the left dorsolateral prefrontal cortex for 20 min. There are at least 72 hours between stimulation sessions. The patients conduct three cognitive tasks from the CANTAB neuropsychological battery for schizophrenia during stimulation including a working memory task, a cognitive flexibility task, and an emotion recognition task. Mood stability is also evaluated before and after each stimulation session with the Positive and Negative Affect Scale (PANAS).

Official Title
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The Impact of Transcranial Direct and Alternating Stimulation of the Prefrontal Cortex at Different Intensities and Frequencies on Cognition of Schizophrenic Patients

Conditions
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Schizophrenia, Cognitive Dysfunction

Intervention / Treatment
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* Device: transcranial direct current stimulation (tDCS)
* Device: transcranial alternating current stimulation (tACS)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Diagnosis of schizophrenia based on DSM V, Being 18-50 years old (male and female) If female, negative urine pregnancy test feasibility for tDCS interventions according to safety guidelines stable medication regime especially the classical neuroleptics and all CNS-activating medications, if taken, 4-6 weeks before the experiment fluency in the native language right-handed Required written informed consent signed by patients' guardian Exclusion Criteria: pregnancy alcohol or substance dependence history of seizure history of neurological disorder history of head injury Presence of ferromagnetic objects in the body that are contraindicated for brain stimulation of the head (pacemakers or other implanted electrical devices, brain stimulators, some types of dental implants, aneurysm clips, metallic prostheses, permanent eyeliner, implanted delivery pump, or shrapnel fragments) or fear of enclosed spaces).

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Parallel group and each group with crossover design
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: tDCS group<br>The tDCS arm receives two real (or active) stimulation at 2 mA and 3 mA intensities and one placebo electrical stimulation for 20 minutes. | Device: transcranial direct current stimulation (tDCS)<br>* In tDCS, direct electrical currents at the intensity of interest (2 mA for example) are generated by an electrical stimulator and are noninvasively delivered to the scalp through a pair of saline-soaked sponge electrodes (7×5 cm).<br>|
| Active Comparator: tACS group<br>The tACS arm receives two real (or active) stimulation at 8 Hz and 40 Hz frequencies and one placebo alternating electrical stimulation for 20 minutes. | Device: transcranial alternating current stimulation (tACS)<br>* In tACS, alternating electrical currents at the frequency of interest (8 Hz for example) are generated by an electrical stimulator and are noninvasively delivered to the scalp through a pair of saline-soaked sponge electrodes (7×5 cm).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Spatial Working Memory behavioral performance | The test begins with a number of coloured squares (boxes) shown on the screen. The aim of this test is that by selecting the boxes and using a process of elimination, the participant should find one yellow 'token' in each of a number of boxes and use them to fill up an empty column on the right-hand side of the screen. | During procedure (4 minutes) | 
| executive function behavioral performance | The participant is shown two displays containing three coloured balls. The test administrator first demonstrates to the participant how to move the balls in the lower display to copy the pattern in the upper display and completes one demonstration problem, where the solution requires one move. The participant must then complete three further problems, one each requiring two moves, three moves and four moves. Next the participant is shown further problems and must work out in their head how many moves the solutions require and then select the appropriate box at the bottom of the screen to indicate their response | During procedure (8-10 minutes) | 
| Emotional recognition behavioral performance | Computer-morphed images derived from the facial features of real individuals, each showing a specific emotion, are displayed on the screen, one at a time. Each face is displayed for 200 milliseconds and then immediately covered up to prevent residual processing of the image. The participant must select which emotion the face displayed from 6 options (sadness, happiness, fear, anger, disgust or surprise) | During procedure (60 minutes) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The Positive and Negative Affect Schedule (PANAS) | The Positive and Negative Affect Schedule (PANAS) is a self-report questionnaire that consists of two 10-item scales to measure both positive and negative affect. Each item is rated on a 5-point scale of 1 (not at all) to 5 (very much). | through study completion in each experimental session up to 1 hour | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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schizophrenia, tDCS, tACS, Cognition, dorsolateral prefrontal cortex