The goal of this clinical trial is to learn if brain stimulation can help children ages 6 to 12 with attention-deficit/hyperactivity disorder (ADHD) improve their attention and self-control. The main questions it aims to answer are: Does intermittent theta burst stimulation (iTBS) improve performance on a task that tests attention and reaction times? Can brain activity and genetics help predict who benefits most from this treatment? Researchers will compare randomly assigned active iTBS to sham (inactive) stimulation groups to see if the treatment helps. Participants will: Receive 10 sessions of either active or sham iTBS over 2 weeks Complete a computer task measuring attention before and after stimulation Wear a brain cap during the task to record EEG signals, also take part in resting-state brain scans, namely magnetic resonance imaging (MRI) and functional near-infrared spectroscopy (fNIRS), and provide a saliva sample for genetic testing
This study explores whether noninvasive brain stimulation can improve attention control in children diagnosed with Attention-Deficit/Hyperactivity Disorder (ADHD), and how biological factors such as brain activity, brain structure, and genetics may predict individual differences in response. The primary focus is on executive attention-the ability to focus on relevant information, ignore distractions, and resolve conflicts between competing signals. These skills are often impaired in children with ADHD and closely linked to underlying differences in brain function. To address this, the study uses intermittent theta burst stimulation (iTBS), a specialized form of transcranial magnetic stimulation (TMS). This method delivers rapid bursts of magnetic energy in intervals that are designed to increase the excitability of the targeted brain region. The stimulation is applied to the right dorsolateral prefrontal cortex (DLPFC), a key area involved in attention regulation, response inhibition, and cognitive control-functions that are often altered in ADHD. A total of 40 children between the ages of 6 and 12 will participate. All must have a confirmed diagnosis of ADHD, verified through structured clinical evaluation. To ensure task comprehension and protocol tolerance, all participants must meet a minimum cognitive ability threshold based on a brief IQ screening. Participants are randomly assigned to receive either active iTBS or sham stimulation. In the sham condition, the procedures and equipment appear identical, but the stimulation coil is positioned in a way that does not affect brain activity. This ensures that results can be attributed to the stimulation itself rather than expectations or placebo effects. Both participants and researchers conducting assessments are unaware of group assignments to maintain blinding. Each participant undergoes ten sessions of either active or sham iTBS, typically spaced across two weeks. The stimulation protocol is brief-each session lasting only a few minutes-and individualized according to motor threshold testing, which ensures the intensity is appropriate and safe for each child. All procedures are delivered under professional supervision in a child-friendly environment with appropriate hearing protection. To assess attentional performance, children complete the Attention Network Test (ANT) before and after the stimulation phase. This computerized task measures three key domains of attention: alerting, orienting, and executive control. During the task, children respond to the direction of arrows on the screen, which may be surrounded by distracting cues. This allows researchers to calculate specific reaction-time profiles associated with attention and conflict resolution. While the ANT is being performed, the study also records electroencephalographic (EEG) data to capture the brain's electrical responses to each trial. EEG is a noninvasive method that tracks fast neural signals in real time using a cap placed on the child's head. It allows for detailed analysis of how the brain prepares for, reacts to, and regulates attentional demands-especially in the milliseconds following stimulus presentation. In addition, resting-state fNIRS recordings are collected before and after the intervention. fNIRS is a child-friendly brain imaging method that uses near-infrared light to measure blood oxygen levels in the cortex. When the child is at rest, this technique provides insight into the baseline functional state of the DLPFC, allowing researchers to detect changes in regional activation associated with the stimulation. To explore whether structural brain features may predict stimulation outcomes, each participant also undergoes a one-time MRI scan. This provides high-resolution images of brain anatomy and can reveal differences in cortical thickness, brain volume, or regional structure that may relate to ADHD symptoms or treatment response. Finally, the study collects genetic material from saliva samples to investigate specific single-nucleotide polymorphisms in genes linked to dopamine signaling, synaptic function, or neurodevelopment. These include candidate genes such as DRD4, DAT1, COMT, and SLC6A3, which have been associated with attentional control and ADHD phenotypes. Genetic data will be used to explore biological moderators of iTBS efficacy. This multimodal approach-combining behavioral, electrophysiological, neuroimaging, and genetic methods-aims to move beyond the question of whether iTBS is effective for ADHD. Instead, it seeks to understand how and for whom it works, contributing to the long-term development of individualized, evidence-based neuromodulation strategies for children with attentional difficulties. The study complies with ethical standards for pediatric research and brain stimulation, and is overseen by the Local Ethical Committee of Al-Farabi Kazakh National University. It is funded by the Ministry of Science and Higher Education of the Republic of Kazakhstan under grant number IRN BR27198099. No U.S. FDA-regulated products are involved.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
40
Participants receive intermittent theta burst stimulation (iTBS) applied to the right dorsolateral prefrontal cortex (DLPFC). The protocol consists of 600 pulses delivered in bursts of 3 pulses at 50 Hz, repeated at 5 Hz for 2 seconds, every 10 seconds, over approximately 3 minutes per session. Stimulation is delivered at 80% of the participant's active motor threshold. Ten sessions are administered across two weeks.
Participants receive sham intermittent theta burst stimulation (iTBS) to the right dorsolateral prefrontal cortex (DLPFC) using a placebo coil. The coil replicates the sound and scalp sensation of active stimulation without generating sufficient magnetic output to alter cortical excitability. Session length, coil placement, and stimulation parameters are matched to the active iTBS condition. To preserve blinding, both participants and administering staff wear earplugs to minimize auditory differences between sham and active coils. This condition serves as a placebo control for evaluating iTBS effects on attention in children with ADHD.
Neurolab Plus
Almaty, Kazakhstan
Non-profit joint-stock company "Al-Farabi Kazakh National University"
Almaty, Kazakhstan
Change in Executive Attention Efficiency as Measured by the Attention Network Test (ANT)
Executive attention is measured as the conflict effect (reaction time in incongruent flanker trials - reaction time in congruent flanker trials). Smaller values of reaction time difference (milliseconds, ms) reflect improved conflict resolution and executive control.
Time frame: Baseline and post-intervention (within 7 days of final TMS session)
Change in Event-Related Potentials During ANT (EEG - N2 Component)
Amplitude of N2 (\~200-350 ms) during ANT incongruent vs. congruent trials, reflecting conflict monitoring (µV²/Hz).
Time frame: Baseline and up to 7 days after the final TMS session.
Change in Event-Related Potentials During ANT (EEG - P3 Component)
Amplitude of P3 (\~350-550 ms) during ANT trials, reflecting attentional allocation (µV²/Hz).
Time frame: Baseline and up to 7 days after the final TMS session.
Change in Oscillatory EEG Power During ANT (Theta Band)
Mean theta-band power (4-7 Hz) over fronto-central electrodes during ANT (µV²/Hz).
Time frame: Baseline and up to 7 days after the final TMS session.
Change in Resting-State Prefrontal Activity - Mean Oxygenation (fNIRS)
Resting-state functional near-infrared spectroscopy (fNIRS) measurement of mean oxygenated hemoglobin (HbO, µM) in the dorsolateral prefrontal cortex (DLPFC).
Time frame: Baseline and up to 7 days after the final TMS session.
Change in Resting-State Prefrontal Activity - Functional Connectivity (fNIRS)
Resting-state fNIRS measurement of connectivity indices across DLPFC channels (e.g., correlation coefficients between HbO time series).
Time frame: Baseline and up to 7 days after the final TMS session.
Change in ADHD Symptom Severity (Vanderbilt ADHD Diagnostic Parent Rating Scale, VADPRS)
Parent-reported Vanderbilt ADHD Diagnostic Parent Rating Scale (VADPRS). The questionnaire includes 47 symptom items scored 0-3 ("Never" to "Very Often"), covering inattention, hyperactivity/impulsivity, oppositional-defiant, conduct, and anxiety/depression domains. It also includes 8 performance/impairment items scored 1-5 ("Excellent" to "Problematic"). Higher symptom scores (0-141) indicate greater severity of ADHD-related behaviors, while higher performance scores indicate worse functioning.
Time frame: Baseline and up to 7 days after the final TMS session.
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