Effects of tDCS for Enhancing Cognitive Function in Individuals With Persistent Post-Concussion Syndrome

September 18, 2025 updated by: Dr Yvonne Han, The Hong Kong Polytechnic University

Effects of Transcranial Direct Current Stimulation for Enhancing Cognitive Function in Individuals With Persistent Post-Concussion Syndrome: A Pilot fMRI/1H-MRS Study

Globally, 10 million new traumatic brain injury (TBI) cases are estimated annually, with mild traumatic brain injury (mTBI) accounting for 75-90% of all TBI cases. It is estimated that 40-80% of individuals with mTBI may experience the post-concussion syndrome (PCS), which is characterized by a range of physical, cognitive, and emotional symptoms. Although the underlying basis of cognitive dysfunction of patients with persistent PCS remains to be clarified, converging evidence shows that the clinical symptoms is underpinned by abnormal neural information processing as a result of axonal injury due to mTBI. Recent studies have demonstrated abnormalities in both structural and functional cortical connectivity, and a loss of cortical excitability-inhibitory (E/I) balance after TBI. Yet, there is no consensus for treating chronic symptoms of concussion, and PCS remains a chronic and highly disabling condition. One potential treatment option is transcranial direct current stimulation (tDCS), a non-invasive brain stimulation technique that has been shown to modify behavior by enhancing connectivity between targeted brain areas. However, research on the therapeutic effect of tDCS on PCS symptoms is limited, and the neurologic mechanisms underlying its effects are not well understood. The proposed study aims to address these knowledge gaps by examining the effects of tDCS on the central nervous system function in patients with PCS, with a specific focus on functional cortical connectivity and cognitive functions such as processing speed and executive function. The study also aims to add value to existing evidence by potentially opening new directions for designing intervention programs for the treatment of PCS after mTBI.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
40

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Hong Kong
    • Kowloon
      • Hung Hom, Kowloon, Hong Kong
        • Recruiting
        • The Hong Kong Polytechnic University
        • Contact:
          • Yvonne Han, PhD
          • Phone Number: +852 2766 7578

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • being 18 years old or older;
  • having a history of a mild TBI (less than 30 minutes loss of consciousness) 1-6 years prior to the study;
  • able to communicate in Chinese.

Exclusion Criteria:

  • being without a confirmed diagnosis from the medical practitioner;
  • having a history of other neurological and psychiatric disorders, skull defect, recent medical instability (within 3 weeks);
  • being pregnant;
  • being medication for a psychiatric condition (e.g., major depression, anxiety, schizophrenia);
  • with any implanted devices or suffering from real claustrophobia or feel uncomfortable in small, enclosed spaces, like MRI tunnel

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Active-tDCS
For active-tDCS condition, participants will receive stimulation on the dorsolateral prefrontal cortex with ramp up and ramp down mode for 10 seconds, eliciting a tingling sensation on the scalp that fades over seconds.
Device: tDCS with cognitive training programme
Participants will complete tDCS over 10 sessions in 2 weeks (once per day, for 10 consecutive working days), while performing the executive function training tasks. The training session will last for 20 minutes and it is comprised of 5 exercises targeting at information processing speed and executive function capacities. Each exercise lasts for approximately 4 minutes, totaling approximately 20 minutes.
Sham Comparator: Sham-tDCS
For sham-tDCS condition, participants will receive initial stimulation with ramp up and ramp down mode for 30 seconds, eliciting a tingling sensation on the scalp then it will be discontinued.
Device: tDCS with cognitive training programme
Participants will complete tDCS over 10 sessions in 2 weeks (once per day, for 10 consecutive working days), while performing the executive function training tasks. The training session will last for 20 minutes and it is comprised of 5 exercises targeting at information processing speed and executive function capacities. Each exercise lasts for approximately 4 minutes, totaling approximately 20 minutes.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Average standardised score of executive function tests
Time Frame: First day of intervention, 1 day after the last day of intervention (2 time points, up to 2 weeks)
The executive function of the PCS subjects will be assessed using the Executive Composite score, which combines scores from various executive function tests.Simple-task processing speed will be evaluated using the CANTAB® 5-choice Reaction Time (RTI) task, which measures the ability to focus on relevant information while ignoring distractions. It requires participants to react as soon as a yellow dot appears on screen. Complex-task processing speed will be assessed using the computerized version of the Wisconsin Card Sorting Test (WCST), which assesses cognitive flexibility. The test requires subjects to correctly match the response cards with several stimulus cards according to feedback provided based on a rule. The mean reaction time is calculated for the trials giving a correct answer during WCST. The reaction time measured from both tasks will be converted to standard scores and averaged to yield an executive composite score. Lower scores indicate poorer executive functioning.
First day of intervention, 1 day after the last day of intervention (2 time points, up to 2 weeks)

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change in CANTAB® cognitive test - Reaction Time (RTI)
Time Frame: First day of intervention,1 day after the last day of intervention (2 time points, up to 2 weeks)
RTI assesses motor and mental response speeds, reaction time, response accuracy and impulsivity. It consists of 30 trials with five potential targets and requires participants to make flexible responses as fast as possible to the target stimulus (shown in yellow). Specifically, movement and reaction time will be measured, where shorter duration reflects faster processing speed.
First day of intervention,1 day after the last day of intervention (2 time points, up to 2 weeks)
Change in CANTAB® cognitive test - Multitasking Test (MTT)
Time Frame: First day of intervention,1 day after the last day of intervention (2 time points, up to 2 weeks)
MTT assesses the ability to resolve the interference of task-irrelevant information (stroop-like effect). The test displays an arrow which can appear on either the left or right side of the screen and can point to either the left or right side. In each trial, participants are presented with a cue that indicates which button to press according to two different rules. And the rules that participants have to follow may change from trial to trial in a randomized order. Participant's response latencies and error scores will be measured.
First day of intervention,1 day after the last day of intervention (2 time points, up to 2 weeks)
Change in CANTAB® cognitive test - Spatial Working Memory (SWM)
Time Frame: First day of intervention,1 day after the last day of intervention (2 time points, up to 2 weeks)
SWM assess the memory ability of visuospatial information. Participants are required to search the tokens from a number of boxes but not pressing the boxes which tokens have been found. Errors (lower scores indicate lower repetition on pressing the same boxes that token has been found) and strategy (lower scores suggest higher strategy use in begin of choosing the same boxes) will be measured.
First day of intervention,1 day after the last day of intervention (2 time points, up to 2 weeks)

Other Outcome Measures

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Exploratory mediator - default mode network (DMN) activation
Time Frame: First day of intervention,1 day after the last day of intervention (2 time points, up to 2 weeks)
The DMN activation, indexed by fMRI resting state data will be assessed. Neuroimaging data will be acquired from the whole brain using a 64-channel head coil on a 3T Siemens MRI scanner. Resting-state data will be registered to each participant's high-resolution structural image and then normalized into the standard Montreal Neurological Institute (MNI) space. Mediation analyses will be performed to determine if the enhanced network organization in PCS patients, as indexed by DMN activation, will mediate the beneficial effect of tDCS
First day of intervention,1 day after the last day of intervention (2 time points, up to 2 weeks)
Exploratory mediator - excitability-inhibitory (E/I) ratio
Time Frame: First day of intervention,1 day after the last day of intervention (2 time points, up to 2 weeks)
The E/I ratio, indexed by MRS data will be assessed. The MRS acquisition protocol is adopted from Sapey-Triomphe and the colleagues. Magnetic resonance spectra will be acquired using the Hadamard Encoding and Reconstruction of MEGA-Edited Spectroscopy (HERMES) sequence, allowing for simultaneous quantification of GABA + and Glx (glutamine and glutamate). The MRS acquisition parameters will be set as follows: 320 averages, TR = 2000 ms, TE = 80 ms, 2048 data points, 2000 Hz spectral width, MOIST water suppression, 90°excitation/180°refocusing pulses, 20 ms editing pulses at frequencies 1.9 ppm for GABA. Interleaved Water Reference correction will be used to limit the effect of scanner drift. Twenty unsuppressed water reference scans (at TE = 80 ms) will also be acquired. Mediation analyses will be performed to determine if the enhanced network organization in PCS patients, as indexed by E/I balance, will mediate the beneficial effect of tDCS
First day of intervention,1 day after the last day of intervention (2 time points, up to 2 weeks)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
The Hong Kong Polytechnic University

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Yvonne Han, PhD, The Hong Kong Polytechnic University

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 Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
September 1, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
August 1, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
February 1, 2028

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
April 8, 2024

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 18, 2024

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
April 19, 2024

Study Record Updates

Last Update Posted (Estimated)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
September 19, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 18, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2025

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • HSEARS20240223001

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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