Autism Spectrum Disorder (ASD), Electroencephalography, Transcranial Direct Current Stimulation (tDCS)
Conditions
Brief summary
Background: Transcranial Direct Current Stimulation (tDCS) is a form of non-invasive brain stimulation that has aroused increased interests in the past decade. Not only that it is transient with little side-effects, and can be well-tolerated by children, it is also affordable and readily accessible, making it an appealing treatment option for autism spectrum disorder (ASD). Objective: (1) To evaluate the therapeutic effects of tDCS on improving cognitive function in patients with ASD, (2) to better understand the neural mechanisms underlying the neuromodulation effects of tDCS in patients with ASD, and (3) to determine whether resting-state functional connectivity measures can predict the therapeutic effects of active tDCS in individuals with ASD. Methods: To assess the therapeutic effects and neural mechanisms of tDCS, 90 adolescents with ASD (age 12-22 years) will receive three stimulation conditions: cathodal tDCS of the left DLPFC, anodal tDCS of the left DLPFC and sham-tDCS with at least a week apart each time. During the active tDCS or sham-tDCS condition, the participants will be administered a computerized test battery (Cambridge Neuropsychological Test Automated Battery, CANTAB®) to evaluate their cognitive function. EEG before and after the tDCS to evaluate the tDCS-induced alteration in their neural activity and functional connectivity. Hypothesis: Drawing together the different evidence linking ASD with cortical hyper-excitability and disordered neural connectivity, as reviewed previously, the investigators hypothesize that, relative to a sham-tDCS condition, active cathodal (inhibitory) and anodal (excitatory) tDCS over the left DLPRC will induce stimulation-linked facilitation of learning and resultant improvement of cognitive functioning in patients with ASD. In addition to the therapeutic effects of tDCS, enhanced neural connectivity, as indexed by altered level EEG theta coherence in patients with ASD, will mediate the beneficial effects of tDCS, relative to sham tDCS, on improvements in cognitive function. Moreover, resting-state functional connectivity will moderate the beneficial effects of active tDCS on cognitive function, relative to sham tDCS, such that participants with greater pre-treatment resting state functional connectively will evidence greater/less response to tDCS, relative to participants receiving sham tDCS.
Interventions
DEVICEtDCS
Participant will receive three stimulation conditions: cathodal tDCS of the left DLPFC, anodal tDCS of the left DLPFC and sham-tDCS. The order of the conditions will be randomized and counterbalanced across participants, and the three stimulation conditions will be administered at least a week apart to avoid carry-over effects. The tDCS session will last for 20 minutes.
Sponsors
The Hong Kong Polytechnic University
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
TREATMENT
Masking
TRIPLE (Subject, Caregiver, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
12 Years to 22 Years
Healthy volunteers
No
Inclusion criteria
* being 12-22 years old * diagnosed with ASD given by registered psychiatrists or clinical psychologists according to the Diagnostic and Statistical Manual of Mental Disorders-5th Edition (DSM-5) criteria of ASD * able to communicate in Chinese
Exclusion criteria
* without a confirmed diagnosis from the clinical psychologist * history of other neurological and psychiatric disorders and head trauma * on psychiatric medication
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in CANTAB® cognitive test - Reaction Time (RTI) | During each stimulation session, last around 3mins | 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. |
| Change in CANTAB® cognitive test - Spatial Working Memory (SWM) | During each stimulation session, last around 6mins | SWM assesses retention and manipulation of visuospatial information. 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 of the screen by selecting the boxes and using a process of elimination. Error selecting boxes that have already been found to be empty and revisiting boxes which have already been found to contain a token will be measured. |
| Change in CANTAB® cognitive test - Multitasking Test (MTT): Response Latencies | During each stimulation session, last around 8mins | 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 will be measured. |
| Change in CANTAB® cognitive test - Multitasking Test (MTT): Error Scores | During each stimulation session, last around 8mins | 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 error scores will be measured. |
| Changes in EEG theta coherence | Before tDCS session, Right after tDCS session (2 timepoints, up to 20 minutes) | Each participant will be tested individually to collect EEG data. The participants' eyes-open resting condition will be assessed by EEG for 5 minutes, before and after the tDCS to evaluate the tDCS-induced alteration in their neural activity and functional connectivity. Raw data will be processed with the EEGLAB Toolbox using MATLAB® R2019a. Data from 19 electrodes will be used for analysis. |
Countries
Hong Kong
Contacts
Primary ContactYvonne Han, PhD
Outcome results
None listed