Effects of Transcranial Direct Current Stimulation for Enhancing Cognitive Function in Individuals With Autism Spectrum Disorder - A Pilot fMRI Study

November 5, 2026 updated by: Dr Yvonne Han, The Hong Kong Polytechnic University

Autism Spectrum Disorder (ASD) is a pervasive neurodevelopmental disorder that currently affects 1 in 32 children. ASD is characterized by persistent deficits in social communication and restricted, repetitive behaviors. For instance, people with ASD often show great difficulty in recognizing social cues and understanding others' emotions, as well as having a tendency to act inflexibly and inappropriately in social situations, all of which contribute to lifelong social and occupational dysfunctions.To date, there is no cure for ASD. Existing treatments are primarily behavioral or educational based. Although some treatments show positive therapeutic effects in reducing patients' core autistic symptoms, the interventions are often labor- and time-intensive. Recently, a non-invasive painless brain stimulation technique, "transcranial direct current stimulation (tDCS)," has received increasing interest in clinical settings as a potential tool for cognitive enhancement and neurorehabilitation for various cognitive dysfunctions. This study aims to examine the effectiveness of tDCS treatment combined with cognitive training for individuals with ASD. We will study the effect before and after treatment.

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:

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

12 years to 21 years (Child, Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

Male

Description

Inclusion Criteria:

  • 12-21 years old;
  • Score of 60 or above on an intelligence test;
  • Able to communicate in Chinese;
  • Diagnosed with Autism Spectrum Disorder (ASD)

Exclusion Criteria:

  • Diagnosed with Developmental Coordination Disorder (DCD);
  • Diagnosed with other neurological or psychiatric disorders;
  • Previous history of brain-stimulation-induced mental or psychological disorder;
  • Presence of metal or other types of implants;
  • Suffers from claustrophobia, or is unable to stay still in confined or narrow spaces

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 the active-tDCS condition, participants will receive a stimulation on the dorsolateral prefrontal cortex, with ramp up and ramp down mode for 30 seconds, eliciting a tingling sensation on the scalp that fades over seconds.
Device: Active-tDCS with computerized cognitive training

Participants will receive active-tDCS over 10 sessions in 2 weeks (20 minutes per session, once per day, for 10 consecutive working days), with concurrent computerized cognitive training. The training comprises of 10 games targeting multiple executive functions.
Sham Comparator: Sham-tDCS

For sham-tDCS condition, participants will receive an initial stimulation of a ramp up and ramp down mode for 30 seconds, eliciting a tingling sensation on the scalp. Then the stimulation will be discontinued.
Device: Sham-tDCS with computerized cognitive training

Participants will receive sham-tDCS over 10 sessions in 2 weeks (20 minutes per session, once per day, for 10 consecutive working days), with concurrent computerized cognitive training. The training comprises of 10 games targeting multiple executive functions.

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
Change in Executive Functioning - Executive Composite Score
Time Frame: First day of intervention, and 1 day after the last day of intervention. (2 time points, up to 2 weeks)

Derived by summing the scores from the test battery of executive functions. To reduce the number of statistical comparisons, one Executive Composite score will be computed from the different executive function measures. This will be done by converting the raw scores on the different executive function measures to Z scores. The Z scores from the different executive function measures will then be averaged to yield the Executive Composite score. Lower scores indicate poorer executive functioning.
First day of intervention, and 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 subdomains of executive function - CANTAB® cognitive test: Reaction Time (RTI)
Time Frame: First day of intervention, and 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
First day of intervention, and 1 day after the last day of intervention. (2 time points, up to 2 weeks)
Change in subdomains of executive function - CANTAB® cognitive test: Spatial Working Memory (SWM)
Time Frame: First day of intervention, and 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, and 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, and 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, and 1 day after the last day of intervention. (2 time points, up to 2 weeks)
Change in CANTAB® cognitive test - Emotion Recognition Task (ERT)
Time Frame: First day of intervention, and 1 day after the last day of intervention. (2 time points, up to 2 weeks)

ERT assesses the ability to identify six basic emotions in facial expressions along a continuum of expression magnitude. Participants must select which emotion the facial image displayed 0.2s ago. Response latencies and accuracy will be measured.
First day of intervention, and 1 day after the last day of intervention. (2 time points, up to 2 weeks)
Change in subdomains of executive function - Verbal Fluency Test (VFT)
Time Frame: First day of intervention, and 1 day after the last day of intervention. (2 time points, up to 2 weeks)

The VFT assesses an individual's ability of working memory retrieval and executive control by instructing the individual to generate words for given semantic categories within a limited time. Participants will be given one minute for each category, which will be counterbalanced across participants to avoid order effects. The number of unique and correct words generated will be counted for each of the participants.
First day of intervention, and 1 day after the last day of intervention. (2 time points, up to 2 weeks)
Change in subdomains of executive function - Five-Point Test (FPT)
Time Frame: First day of intervention, and 1 day after the last day of intervention. (2 time points, up to 2 weeks)

The FPT assess an individual's design fluency and mental flexibility through instructing the individual to create unique, geometric patterns. Participants will be given a sheet of paper containing an array of 40 identical boxes. Each box contains 5 dots, arranged in the same pattern as '5' on a standard die. Participants have to connect 2 or more of the 5 dots using straight lines to create as many unique designs as possible within 5 minutes. The number of unique and correct patterns generated will be counted for each of the participants at 3 minutes and 5 minutes.
First day of intervention, and 1 day after the last day of intervention. (2 time points, up to 2 weeks)
Change in subdomains of executive function - Color Trails Test (CTT)
Time Frame: First day of intervention, and 1 day after the last day of intervention. (2 time points, up to 2 weeks)

CTT is a test that measures attention, processing speed, and flexibility. In Part 1, participants will connect numbered circles in sequential order as fast as possible. In Part 2, participants will also numbers in order, but must also alternate between circles of two different colors (pink and yellow). The execution time will be measured.
First day of intervention, and 1 day after the last day of intervention. (2 time points, up to 2 weeks)
Changes in subdomains of executive function - d2 Test of Attention
Time Frame: First day of intervention, and 1 day after the last day of intervention. (2 time points, up to 2 weeks)

The d2 Test of Attention measures selective and sustained attention, as well as visual information processing. Participants will be given 14 rows with 40 characters each, of which they must scan each row and cross out every target item (the letter 'd' with 2 dashes either above, below, or one in each position). Therefore, participants much ignore distractors along each row (i.e. the letter 'p' with any number of dashes, or 'd' with the wrong number of dashes). The number of errors will be counted for each participant.
First day of intervention, and 1 day after the last day of intervention. (2 time points, up to 2 weeks)
Change in social responsiveness - Social Responsiveness Scale-2nd edition (SRS-2)
Time Frame: First day of intervention, and 1 day after the last day of intervention (2 time points, up to 2 weeks)

SRS-2 is a sensitive measure of social functioning in individuals that detects even subtle symptoms that are highly related to ASD. It uses a four-point scale and focuses on different aspects of socialization. The total score reflects the clinical effectiveness of tDCS, and higher scores indicate greater symptom severity. It has been shown that SRS-2 is sensitive to detect changes in social communication improvement related to improved cognitive functioning after treatment.
First day of intervention, and 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 - Excitability-Inhibitory (E/I) ratio
Time Frame: First day of intervention, and 1 day after the last day of intervention. (2 time points, up to 2 weeks)

The study proposed will examine the biological mediator variable, E/I ratio, to explain the effects of tDCS. MRI data will be collected in the resting-state before and immediately after the 10-session intervention program. Further network analysis will be performed to characterize broader shifts in functional brain connectivity.
First day of intervention, and 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, 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 (Estimated)

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.
November 16, 2026

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.
September 30, 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.
September 30, 2027

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).
October 30, 2026

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.
November 5, 2026

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.
November 12, 2026

Study Record Updates

Last Update Posted (Actual)

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.
November 12, 2026

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.
November 5, 2026

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.
October 1, 2026

More Information

Terms related to this study

Keywords

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.
  • HSEARS20260821003

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

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