Supporting Cognitive Control Training With tDCS

Study Overview
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Brief Summary
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Cognitive control (CC) is an important prerequisite for goal-directed behaviour and often associated with dysfunctional prefrontal activity within the cortex. This can be ameliorated by non-invasive brain stimulation. In this randomised single-blind study we compare effects of transcranial direct current stimulation (tDCS) on CC in healthy subjects. The study includes 162 subjects who undergo a two-week (six sessions) training of cognitive control (adaptive paced auditory serial addition task, PASAT) supported by tDCS. Subjects are randomised to receive either concurrent anodal, cathodal, or sham tDCS with an intensity of 1 mA or 2 mA of their left (F3) or right (F4) PFC, resulting in eight stimulation groups. Stimulation effects on performance changes are compared to a sham control group.Changes in Affective state are measured by the positive and negative affect schedule (PANAS), possible transfer effects are assessed by the Eriksen Flanker task. Stability of effects is measured up to three months after the last intervention.

Official Title
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Lasting Amelioration of Deficient Cognitive Control by Transcranial Direct Current Stimulation (tDCS)-Enhanced Training

Conditions
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Cognitive Control

Intervention / Treatment
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* Behavioral: Effect of tDCS on cognitive control task performance


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy subjects Right-handed (assessed by Edinburgh Handedness Inventory) No other concurrent brain stimulation during participation Proficient in German (min. CEFR level B) Ability to strictly adhere to study timeline Exclusion Criteria: Diagnosed neurological illnesses Diagnosed psychiatric disorders Achromatopsia Metallic implants / tattoos on or near electrode sites Consumption of tobacco to an equivalent of ten or more cigarettes per day Prior participation in experiments involving the PASAT

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

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
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Sham Comparator: Sham<br>Sham tDCS (ramp up and ramp down of electrical current before as well as after task performance to elicit physical sensations similar to verum tDCS) | Behavioral: Effect of tDCS on cognitive control task performance<br>* Added verum or sham tDCS while working on a cognitive control task.<br>|
| Active Comparator: L1A<br>Active tDCS laterality: left PFC (F3; second electrode placed on deltoid muscle of the opposing arm) intensity: of 1 mA polarity: anodal | Behavioral: Effect of tDCS on cognitive control task performance<br>* Added verum or sham tDCS while working on a cognitive control task.<br>|
| Active Comparator: R1A<br>Active tDCS laterality: right PFC (F4; second electrode placed on deltoid muscle of the opposing arm) intensity: of 1 mA polarity: anodal | Behavioral: Effect of tDCS on cognitive control task performance<br>* Added verum or sham tDCS while working on a cognitive control task.<br>|
| Active Comparator: L2A<br>Active tDCS laterality: left PFC (F3; second electrode placed on deltoid muscle of the opposing arm) intensity: of 2 mA polarity: anodal | Behavioral: Effect of tDCS on cognitive control task performance<br>* Added verum or sham tDCS while working on a cognitive control task.<br>|
| Active Comparator: R2A<br>Active tDCS laterality: right PFC (F4; second electrode placed on deltoid muscle of the opposing arm) intensity: of 2 mA polarity: anodal | Behavioral: Effect of tDCS on cognitive control task performance<br>* Added verum or sham tDCS while working on a cognitive control task.<br>|
| Active Comparator: L1C<br>Active tDCS laterality: left PFC (F3; second electrode placed on deltoid muscle of the opposing arm) intensity: of 1 mA polarity: cathodal | Behavioral: Effect of tDCS on cognitive control task performance<br>* Added verum or sham tDCS while working on a cognitive control task.<br>|
| Active Comparator: R1C<br>Active tDCS laterality: right PFC (F4; second electrode placed on deltoid muscle of the opposing arm) intensity: of 1 mA polarity: cathodal | Behavioral: Effect of tDCS on cognitive control task performance<br>* Added verum or sham tDCS while working on a cognitive control task.<br>|
| Active Comparator: L2C<br>Active tDCS laterality: left PFC (F3; second electrode placed on deltoid muscle of the opposing arm) intensity: of 2 mA polarity: cathodal | Behavioral: Effect of tDCS on cognitive control task performance<br>* Added verum or sham tDCS while working on a cognitive control task.<br>|
| Active Comparator: R2C<br>Active tDCS laterality: right PFC (F4; second electrode placed on deltoid muscle of the opposing arm) intensity: of 2 mA polarity: cathodal | Behavioral: Effect of tDCS on cognitive control task performance<br>* Added verum or sham tDCS while working on a cognitive control task.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cognitive performance | Changes in performance in the PASAT (as assessed by number of correct trials within each PASAT session) due to the various tDCS interventions. All eight interventions will be compared to the sham group. Cognitive performance is modified by tDCS, which is applied through a multi-channel stimulator (DC-Stimulator MC, NeuroConn GmbH, Ilmenau, Germany; software version 1.3.8; two rectangular rubber electrodes (5 x 7 cm)). | 2 to 14 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Affective state | Changes in affective state over the course of the experiment (assessed by the positive and negative affect schedule (PANAS) questionnaire). Scores are calculated for negative and positive affect separately, by summing up the respective answers. | 2 weeks | 
| Transfer effect | Transfer effects in the Eriksen Flanker task (assessed through mean reaction times). Means are calculated for congruent, incongruent, and neutral trials respectively. | 3 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Brain stimulation, Cognitive training, Cognition, Cognitive enhancement, Transcranial direct current stimulation