The Effect of Different Intensities of Bilateral- and Cathodal-tDCS in Healthy Individuals

Not Applicable

Completed

• Conditions: Healthy
• Interventions: Device: Sham cathodal-tDCS; Device: Cathodal-Transcranial direct current stimulation (cathodal-tDCS); Device: Bilateral-Transcranial direct current stimulation (bilateral-tDCS); Device: Sham bilateral-tDCS

• Registration Number: NCT05929014
• Lead Sponsor: Mahidol University

Brief Summary

This study will be divided into 2 sub-study 1) To investigate the effects of 1 mA, 1.5 mA, and 2 mA of bilateral- tDCS on cortical activity and motor/cognitive performances in healthy individuals 2) To investigate the effects of 1 mA, 1.5 mA, and 2 mA of cathodal-tDCS on cortical activity and motor/cognitive performances in healthy individuals.

Detailed Description

Transcranial direct current stimulation (tDCS) is one of the non-invasive brain stimulation (NIBS) techniques. It delivers weak direct current through the scalp via two electrodes. tDCS has been shown to modulate cortical excitability in polarity-specific effects; anodal increases cortical excitability, while cathodal decreases it. tDCS can be applied in two distinct montages: unilateral (an active electrode is applied over the cerebral cortex, while a reference electrode is applied over the contralateral orbit) and bilateral-tDCS (applying two electrodes simultaneously over both cerebral hemispheres). Many tDCS studies have been used as an add-on therapy in stroke patients which aimed to enhance motor re-learning after stroke. Anodal tDCS has been used to enhance cortical excitability in the lesioned hemisphere while cathodal tDCS is used to decrease it in the non-lesioned hemisphere and thus to rebalance the interhemispheric inhibition (IHI). However, there were recent studies reporting the reverse effect of cathodal-tDCS on cortical excitability at high doses. However, the effects of cathodal-tDCS among different doses on cortical excitability and on motor performance are still controversial no report of a non-linear effect for bilateral-tDCS.

The present study will be investigated the effects of different intensities of unilateral cathodal tDCS and bilateral tDCS on cortical activity and functional outcomes in healthy individuals. A single session of different intensities of bilateral-tDCS or cathodal-tDCS (i.e., 1 mA, 1.5 mA, 2 mA vs. sham) will be combined with serial reaction time task (SRTT) in healthy individuals. Cortical activity will be measured as a primary outcome. All power bands (alpha, beta, delta, theta) will be analyzed. Moreover, analysis of brain activity will be also focused on both hemispheres. The reaction time of serial reaction time task and muscle strength will be served as the secondary outcome. Cortical activity and muscle strength will be evaluated before and after the intervention, while reaction time will be evaluated during and after the intervention.

Study Timeline

• Study Start: 2023-06-24
• Study First Submitted: 2023-06-25
• Study First Submitted QC: 2023-06-30
• Study First Posted: 2023-07-03
• Primary Completion: 2023-11-30
• Study Completion: 2024-04-30
• Status Verified: 2024-05
• Last Update Submitted: 2024-05-08
• Last Update Posted: 2024-05-09

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 20

Inclusion Criteria

• 1. Age 18-29 years old
• 2. Righ-hand dominant according to the Edinburgh handedness inventory
• 3. No injury to both upper and lower limb for the past 6 months

Exclusion Criteria

• 1. Presence of any neurological disorders
• 2. Presence of metal implantation, intracranial shunt, cochlear implantation, or cardiac pacemakers
• 3. Presence of opened wound or infectious wound around scalp
• 4. History of epilepsy or any neurological antecedent or unstable condition which can lead to seizure
• 5. Body mass index (BMI) > 30 kg/m2
• 6. Received hormonal treatment and/or drugs that increase sleepiness and affect movement control
• 7. Ischemic heart disease and peripheral vascular ischemia
• 8. Last stage of kidney disease and liver disease

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Sham cathodal-tDCS	Sham cathodal-tDCS	Participants will be received sham of cathodal tDCS during performed serial reaction time task.
Active cathodal-tDCS	Cathodal-Transcranial direct current stimulation (cathodal-tDCS)	Participants will be received different intensities which are 1 mA, 1.5 mA and 2 mA for 20 minutes during performed serial reaction time task. The tDCS will be set with cathodal montage which applied cathodal electrode over left hemisphere and anodal over right orbit.
Active bilateral-tDCS	Bilateral-Transcranial direct current stimulation (bilateral-tDCS)	Participants will be received different intensities which are 1 mA, 1.5 mA and 2 mA for 20 minutes during performed serial reaction time task. The tDCS will be set with bilateral montage which applied anodal electrode over left hemisphere and cathodal electrode over right hemisphere.
Sham bilateral-tDCS	Sham bilateral-tDCS	Participants will be received sham of bilateral tDCS during performed serial reaction time task.

Primary Outcome Measures

Name	Time	Method
Cortical activity	5 minutes	Acquired by electroencephalography (EEG)
The reaction time	30 minutes	Measured the reaction time from serial reaction time task

Trial Locations

Locations (1)

Faculty of Physical Therapy, Mahidol University; 🇹🇭 Salaya, Nakonpathom, Thailand