According to the revised Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) (2013), attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by persistent inattention or hyperactivity-impulsivity that interferes with daily functioning or development [1]. The prevalence of ADHD in children is reported to be approximately 5%, and approximately 4.4% of adults exhibit persistent ADHD symptoms [2]. Notably, 44%–80% of individuals diagnosed with ADHD in childhood continue to experience symptoms into adulthood [3], suggesting that ADHD is not limited to childhood, but rather a condition that can have a lasting impact throughout adulthood.

The core symptoms of ADHD are inattention, hyperactivity, and impulsivity. In addition to these symptoms, children with ADHD exhibit deficits in executive functions, including working memory, inhibitory control, and planning, when compared with their neurotypical peers [4]. These deficits can lead to various long-term issues, such as poor academic performance, interpersonal difficulties, and delinquent behavior [5]. Furthermore, individuals with ADHD have a higher prevalence of comorbid disorders, such as oppositional defiant disorder, conduct disorder, mood disorders, and anxiety disorders [6]. Studies have shown that the presence of these comorbidities worsens prognosis and reduces the efficacy of pharmacological treatments [7]. Consequently, there is increasing advocacy for the incorporation of non-pharmacological interventions in the treatment of ADHD.

Currently, pharmacotherapy is the primary treatment for ADHD, with psychostimulants, such as methylphenidate, being the most commonly used. Non-stimulant medications, such as atomoxetine and clonidine, have also been used [8]. However, pharmacotherapy is often associated with various side effects, including appetite suppression and sleep disturbances, and in some cases, parents may delay or avoid treatment because of concerns about medications [8]. Additionally, it has been reported that approximately 10%–25% of children with ADHD do not respond to medication [9]. As a result, there is an increasing interest in non-pharmacological interventions, either to complement existing treatments or as alternatives for those whom medication is unsuitable.

Non-pharmacological treatments, such as psychoeducation, behavioral parent training, cognitive-behavioral therapy, and social skills training programs, are commonly recommended [10]. Neuromodulation has recently emerged as a promising alternative therapeutic approach. Neuromodulation offers the advantage of being non-invasive and has minimal side effects compared to pharmacotherapy [11,12]. Its efficacy has been demonstrated not only in ADHD but also in various other psychiatric disorders, such as depression, insomnia, anxiety disorders, and obsessive-compulsive disorder [13,14]. In this review, we aimed to provide a comprehensive overview of the current knowledge and advances in neuromodulation techniques for ADHD, focusing on their application in children. Specifically, we explain the basic concepts and mechanisms of three major neuromodulation techniques—neurofeedback, transcranial direct current stimulation (tDCS), and repetitive transcranial magnetic stimulation (rTMS)—and discuss their applications.

This narrative review was conducted through a systematic search of peer-reviewed journals using major databases, including PubMed, PsycINFO, and Web of Science, to identify articles published within the past 10 years. Priority was given to studies conducted in children and adolescents with ADHD to ensure relevance and applicability. This review aimed to explore the potential of neuromodulation as a treatment for ADHD, evaluate its strengths and limitations, and propose future directions for studies in this field.

Definition and mechanism

Neurofeedback is a form of biofeedback that allows patients to monitor and train their brainwaves, enabling them to consciously control their brainwave activity through a non-invasive therapeutic approach [15]. During this process, brainwaves are translated into visual and auditory feedback, such as sounds or animations, providing patients with realtime feedback on their brainwave states. Through repeated training and appropriate reinforcement, patients learn to regulate their brainwave activity, a process grounded in the principles of operant conditioning [16]. Neurofeedback training promotes neuroplasticity, thereby helping to regulate synaptic strength and oscillatory patterns of the brain, which may be pathologically overactive or underactive [17]. This regulatory mechanism restores normal brain function, ultimately improving cognitive and behavioral control in children with ADHD.

Frequency-band protocol

Based on their wave patterns, brain waves are categorized into delta (0.5–4 Hz), theta (4–8 Hz), alpha (8–14 Hz), and sensorimotor rhythm (SMR; 13–15 Hz), which is a type of beta wave, and beta (15–36 Hz) waves. Theta waves typically occur during drowsiness, SMR is associated with passive brain activity, and beta waves are linked to problem-solving, learning, and attention [18]. In children with ADHD, an increase in slow waves has been observed along with the characteristics of a hypoaroused central nervous system, leading to irregular brainwave patterns compared to neurotypical children [18]. Previous studies have suggested that the theta/beta ratio (TBR) can serve as an indicator to differentiate between children with ADHD and neurotypical children [19,20]. In the 1960s, Sterman discovered the SMR waves while studying alert cats under controlled laboratory conditions. These SMR waves, occurring at a frequency of 12–15 Hz, were observed in the sensorimotor cortex and appeared to be associated with a state of focused relaxation, where the animal exhibited alert immobility. In the 1970s, Lubar applied SMR neurofeedback training in children diagnosed with hyperkinetic disorder, now classified as ADHD. Through a series of studies, Lubar demonstrated that SMR neurofeedback could effectively reduce symptoms of hyperactivity and impulsivity in these children [21]. These findings have led to the development and widespread use of neurofeedback protocols that aim to reduce theta waves while enhancing beta- and SMR-wave activities in children with ADHD. Currently, the TBR and SMR protocols are among the most commonly used neurofeedback treatment approaches.

Slow cortical potential protocol

One of the most studied neurofeedback protocol involves the modulation of slow cortical potentials (SCPs), which are event-related potentials characterized by either a positive or negative electrical charge and last from a few hundred milliseconds to several seconds. SCPs are a type of event-related potential. Unlike the consistently observed frequency bands during electroencephalogram (EEG), SCPs occur when a stimulus is anticipated [22]. When an anticipated or intentional stimulus is expected, the term contingent negative variation is used to describe negative SCPs, a concept frequently employed in SCP protocols. Negative SCPs have been associated with improved outcomes in tasks requiring focused preparation, cognitive responses, and problem-solving [22]. Elbert et al. [23] were the first to report that SCPs can be voluntarily controlled using neurofeedback. Later, in 2004, Heinrich applied SCP neurofeedback to treat ADHD and reported a reduction in ADHD symptoms and impulsivity errors compared with a control group of nine individuals [24]. Additionally, in 2006, it was demonstrated that children with ADHD could regulate negative SCPs following SCP neurofeedback, which was associated with symptom improvement [25], A 2007 study comparing the effects of SCP and theta/beta neurofeedback protocols in children with ADHD found that both groups learned to intentionally regulate cortical activity, resulting in improvements in attention, behavior, and cognitive function [26].

Summary of findings on neurofeedback

Key neurofeedback study questions include its effectiveness, comparability with pharmacotherapy, and relative advantages over other treatments. Previous studies have faced criticism for their methodological limitations, including small sample sizes, lack of control groups, non-randomized designs, and unclear inclusion criteria for participants with ADHD [27]. Subsequent studies have addressed these limitations to address these limitations by employing larger randomized controlled trials (RCTs) and sham neurofeedback to better control for non-specific effects. These methodological improvements aimed to assess the effectiveness of neurofeedback in the treatment of ADHD more accurately. This section reviews recent studies that focus on the therapeutic effects of neurofeedback in children with ADHD.

A 2014 meta-analysis of non-pharmacological treatments for ADHD reported that both behavioral modifications and neurofeedback were effective in improving ADHD symptoms [28]. In an analysis of eight RCTs between 2012–2017, Razoki [11] found that although the independent effect of neurofeedback in treating children with ADHD was not definitively proven, neurofeedback reduced the required dosage of medication, and symptom improvement was sustained even after six months of follow-up. This suggests a potential complementary role for neurofeedback in ADHD treatment [11]. A 2018 study comparing the effectiveness of psychostimulant monotherapy with a combination of psychostimulants and neurofeedback in treating ADHD found that combination therapy showed significantly greater treatment efficacy, indicating possible additive effects of neurofeedback [29]. In a review published by Arns et al. [15] in 2020, two meta-analyses confirmed the significant efficacy of standard neurofeedback protocols in reducing symptoms, as evaluated by parents and teachers, with a moderate effect size, and the effects were sustained for 6–12 months. Four multicenter RCTs showed a significant advantage of neurofeedback over semiactive control groups (e.g., attention training), with medium to large effect sizes and remission rates of 32%–47% at the end of treatment and during follow-up [15]. A 2022 metaanalysis by Moreno-García et al. [30] further confirmed that neurofeedback training led to a long-term significant reduction in ADHD symptoms, with effects lasting between 6–24 months post-treatment. This highlights the advantage of neurofeedback in terms of long-term efficacy compared with other treatments, including pharmacotherapy [30]. Additionally, personalized neurofeedback based on individual quantitative EEG frequency data was explored. In a 2024 meta-analysis by Himmelmeier and Werheid [31], three studies examining the effects of personalized neurofeedback were analyzed. Two studies personalized theta/beta neurofeedback using individual alpha peak frequencies, whereas one study used individualized beta rhythms. All the three studies reported significant short- and long-term improvements in ADHD symptoms, as measured by objective tests and questionnaires, compared with standard neurofeedback, sham-neurofeedback, and control groups.

In contrast, several studies concluded that the therapeutic effects of neurofeedback are insufficient. In a 2016 study by Geladé et al. [32], which compared neurofeedback treatment with psychostimulant therapy and physical activity, a psychostimulant treatment group showed superior effectiveness compared with both neurofeedback and physical activity groups. In an RCT by Bink et al. [33], one-year follow-up results indicated insufficient evidence for the added benefits of theta/SMR protocol neurofeedback compared with standard treatment. Similarly, a study by Lee and Jung [34] on the potential additive effects of neurofeedback showed that although a combination of neurofeedback and medication improved ADHD symptoms more than medication alone, there was no significant difference in cognitive function improvement between the two groups. In an RCT by Duric et al. [35], six-month follow-up results showed that the combined treatment of neurofeedback and medication yielded the highest ADHD symptom improvement scores, but the difference was not statistically significant compared with a medication-only group. Furthermore, Geladé et al. [36] reported that improvement following neurofeedback intervention did not persist at a six-month follow-up period.

In conclusion, the National Institutes of Health currently states that study results on neurofeedback as a treatment for ADHD remain mixed [37]. However, based on the findings discussed above, neurofeedback may be effective in improving ADHD symptoms in children and has potential as a complementary treatment, particularly for those who do not respond well to medication or experience side effects. Nonetheless, it is difficult to conclude that neurofeedback alone is as effective as pharmacological treatment.

Definition and mechanism

tDCS is a non-invasive brain stimulation technique that applies a low direct current to the scalp to modulate brain activity. Although the brain is protected by the skull and scalp, approximately 10%–20% of the current can penetrate the cortex, altering neuronal activity [38]. Although the current used is sub-threshold and does not induce action potentials, it modulates the resting membrane potential and influences the activation of N-methyl-D-aspartic acid receptors. Anodal stimulation increases cortical excitability, whereas cathodal stimulation suppresses it [39]. These effects can persist for 30–120 min after stimulation. tDCS poses a lower risk of adverse effects, such as loss of consciousness or seizures than alternating current stimulation [40]. Beyond changes in the resting membrane potential, other theories explaining tDCS effects include brain modeling simulations [41]. The white matter functions as a network for transmitting signals between neurons, and tDCS may influence the pathways through which current flows. Studies using diffusion tensor imaging (DTI) and brain simulations have shown that the anisotropy of white matter significantly affects current distribution and stimulation effects [42]. Therefore, it was hypothesized that tDCS enhances neural interactions via white matter pathways, contributing to its overall neuromodulatory effects.

tDCS protocol in children and adolescents

Several researchers have suggested that tDCS stimulation parameters should be adjusted for children and adolescents, as they differ from those of adults in various ways [43]. In addition to the targeted cortical areas, the developing brains of children with ADHD are considered to have greater neuroplasticity than those of adults, which is an important factor to consider [44]. This increased plasticity suggests that interventions during sensitive developmental periods may have a greater effect. Furthermore, children and adolescents typically have smaller heads than adults, which can result in the generation of stronger electric fields. Given that the effects of tDCS can change non-linearly, depending on the intensity and duration of stimulation [45], careful adjustment of parameters, such as stimulation intensity, duration, and repetition frequency, is crucial.

According to modeling studies, the stimulation intensity required to generate an electric field in children similar to that achieved in adults with ADHD (2 mA, 0.8 V/m) is almost halved to 1 mA (0.6 V/m) in children [46]. Therefore, it may be necessary to adjust the stimulation intensity in children to achieve effects comparable to those observed in adults. Caution must be exercised as higher stimulation intensities can affect areas beyond the targeted electrode sites, potentially leading to unintended clinical outcomes [46]. However, reducing the stimulation intensity may not always be appropriate for all target regions. For example, the intensity required to modulate the dorsolateral prefrontal cortex (DLPFC), which is near the surface, may not be sufficient to reach deeper regions, such as the right inferior frontal gyrus (r-IFG). This limitation may partly explain why some studies targeting the r-IFG in children with ADHD did not show significant effects [47].

Regarding the effects of polarity, cathodal tDCS at 1 mA has been shown to reduce excitability in adults. However, under the same stimulation conditions, it may paradoxically increase excitability in children and adolescents [48]. This reversal of tDCS effects has also been observed in adults when stimulation intensity is increased to 2 mA [49]. Electrode size is another critical factor because smaller electrodes can deliver the desired current density to the brain more effectively at lower current intensities [50]. Given that children’s heads are smaller than those of adults, maintaining a high current localization is advantageous when applying tDCS. If the distance between electrodes is insufficient, there is a risk of short-circuiting the current through the skin. Previous studies have shown that when using 35 cm2 electrodes, the current reaching the brain decreases if the target areas are too close. In particular, the use of 35 cm2 electrodes for bilateral DLPFC stimulation failed to meet the minimum distance required between the electrodes, leading to current short-circuiting, and it was concluded that 25 cm2 electrodes are more suitable for this purpose [46].

Summary of findings on tDCS

According to previous meta-analyses, the effect of tDCS on response inhibition in ADHD has been shown to have a small effect size, particularly with anodal stimulation of the DLPFC. However, for working memory, there was no significant improvement beyond a moderate effect size [51]. The effect size on cognitive control varied significantly, depending on the stimulation protocol used. Regarding ADHD symptoms, tDCS showed a large effect size on the inattention subscale [52], whereas moderate effect sizes were observed for hyperactivity and impulsivity [52,53]. A 2020 meta-analysis by Salehinejad et al. [46] indicated that anodal tDCS could improve impulsivity and inattention in patients with ADHD, suggesting that DLPFC stimulation may be a promising approach for ADHD treatment. Additionally, a 2024 study by Estaji et al. [54] evaluated the effects of tDCS on 24 children with ADHD using three electrode placements (anodal DLPFC [F3]/cathodal vmPFC [Fp2], anodal vmPFC [Fp2]/cathodal DLPFC [F3], and sham stimulation). The results showed that tDCS improved response inhibition and working memory accuracy, but there were no significant improvements in processing speed. This study demonstrated that the left DLPFC and right vmPFC play important roles in emotional regulation in children with ADHD, and that tDCS may modulate these regions to influence function.

In contrast, some studies concluded that the therapeutic effects of tDCS are insufficient. In a 2023 study by Westwood et al. [55], 50 boys with ADHD aged 10–18 years with ADHD participated. They received either anodal or sham tDCS over the right inferior frontal cortex at 1 mA for 20 min across 15 sessions, combined with cognitive training. Results showed that a sham tDCS group exhibited significant improvements in ADHD rating scales and the Conners ADHD Index compared with an anodal tDCS group, with no significant clinical or cognitive improvements observed in other measures. In 2022, Schertz et al. [56] conducted a double-blind, randomized, sham-controlled pilot study with 25 children with ADHD. The participants were randomly assigned to receive either anodal tDCS or sham tDCS for 20 min three times a week for four weeks, totaling 12 sessions. The anodal electrode was placed over the left DLPFC, and the cathode over the vertex. Assessments were conducted before the intervention, after 6 and 12 sessions, and one month after the intervention. No significant differences were observed between the tDCS and sham tDCS groups. Both groups showed significant improvements in ADHD symptoms and executive function on questionnaires. However, computerized performance measures yielded mixed results.

A recent systematic review of tDCS in ADHD identified 14 experimental studies investigating the effects of tDCS. Of these, 10 studies reported partial improvement in cognitive deficits, such as response inhibition, working memory, attention, and cognitive flexibility, as well as clinical symptoms, such as impulsivity and inattention. No serious side effects were reported across 747 tDCS sessions. The DLPFC was the most frequently targeted bilateral area, and anodal tDCS is the most commonly used approach. In adults, stimulation at 2 mA generated a stronger electric field than stimulation at 1 mA, resulting in significant behavioral changes. However, in children with ADHD, even 1 mA is sufficient to induce significant behavioral changes, likely because of their smaller head sizes [46].

In summary, although tDCS shows potential as a method for improving ADHD symptoms, its efficacy appears to vary, depending on the ADHD subtype, which has been suggested as a source of variability in study outcomes. Therefore, further studies with larger sample sizes accounting for ADHD subtypes are necessary to establish its clinical utility. Additionally, factors, such as the cortical regions involved in ADHD pathophysiology, stimulation parameters (intensity, duration, polarity, and electrode size), and symptom types, are critical determinants of tDCS efficacy in ADHD.

Definition and mechanism

Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation technique that utilizes magnetic fields to generate electric currents within the brain, thereby modulating neuronal activity. A magnetic coil positioned on the scalp produces a rapidly fluctuating magnetic field, which penetrates the skull and induces a current in the underlying cortical tissue. This current can depolarize neurons and initiate action potentials, resulting in altered neuronal activity [57]. Unlike tDCS, which modulates resting membrane potential without directly eliciting action potentials, TMS directly induces neuronal firing. Repetitive TMS has demonstrated the ability to modulate cortical excitability, with highfrequency stimulation (≥5 Hz) enhancing excitability and low-frequency stimulation (≤1 Hz) reducing it [58]. The effects of TMS can extend beyond the stimulation period, with potential impacts on brain activity lasting minutes to hours, depending on the applied parameters [59].

TMS is known to target specific brain regions, and its effects are thought to be mediated via synaptic plasticity mechanisms, particularly long-term potentiation and long-term depression [60]. This technique can influence both local cortical circuits and distant regions through white matter pathways, which have been examined using advanced imaging techniques, such as DTI [61]. Similar to tDCS, the anisotropy of white matter may affect how TMS-induced currents are distributed across brain regions, potentially influencing the outcome of stimulation [62]. Generally, TMS is considered a safe modality with a low risk of severe adverse effects. However, seizures remain rare but are possible side effects, particularly in individuals with epilepsy or during high-frequency stimulation protocols [63].

TMS protocol in children and adolescents

Although TMS has been predominantly investigated in adult populations, emerging studies have explored its application in pediatric groups, particularly in conditions, such as ADHD and autism spectrum disorder (ASD) [64]. Given that children’s brains exhibit greater plasticity than adults, the effects of stimulation may be more pronounced and longerlasting [65]. However, enhanced neuroplasticity presents safety and efficacy challenges. It is critical to modify stimulation parameters, such as intensity, frequency, and session duration in pediatric populations, as the developing brain may respond differently from that of an adult [66].

Owing to thinner skulls and reduced brain density in children, the same stimulation intensity used in adults can generate stronger electric fields in pediatric patients. Studies recommend reducing stimulation intensity to approximately 50%–70% of adult levels to achieve comparable effects [67]. Stimulation intensity is typically based on the resting motor threshold (RMT), which tends to be lower in children. Therefore, it is essential to calibrate the intensity relative to the RMT of each child. Additionally, the session frequency and duration must be carefully managed to account for the heightened susceptibility of younger individuals to fatigue and overstimulation. Repeated TMS can induce lasting changes in brain function when applied repetitively. In pediatric populations, initial treatment protocols suggest starting with sessions once daily or 2–3 times per week, with each session lasting between 20–30 min. The total number of sessions varies, depending on the clinical condition, but typically ranges between 10–20. For extended treatment periods, careful monitoring is essential to avoid overstimulation, as the plasticity of the pediatric brain may result in unpredictable responses to prolonged exposure [68]. Coil positioning is a crucial factor in ensuring the efficacy of TMS. Given the smaller head size of children, precise coil placement is essential for accurately targeting the desired brain regions. The DLPFC is commonly targeted in conditions, such as ADHD and depression. However, deeper structures, such as the r-IFG may also be involved. Increasing the stimulation intensity to reach these deeper areas, especially in children, can inadvertently affect adjacent regions, necessitating careful placement and field calculations [69].

Personalization of stimulation parameters is essential when administering TMS to children and adolescents. Given the individual variability in neuroplasticity, skull thickness, and response to stimulation, it is necessary to tailor parameters, such as intensity and session frequency, based on each patient’s initial response. Additionally, the coil size must be carefully considered; smaller coils may be more appropriate for children, as they facilitate localized stimulation and reduce the risk of unintended current spread. If the coils are placed too closely, the current may short-circuit through the skin, reducing the efficacy of the treatment [64]. Although TMS is generally considered safe in the pediatric population, children and adolescents may be more sensitive to its effects. Common side effects include mild headaches, scalp discomfort, and fatigue, particularly at higher stimulation intensities or longer sessions. The risk of seizures is elevated in patients with a history of epilepsy, particularly during highfrequency stimulation. To mitigate this risk, it is critical to adjust the stimulation intensity and ensure sufficient rest between sessions [65].

Summary of findings on TMS

According to previous studies and clinical trials, TMS has demonstrated varying levels of efficacy in mitigating ADHD symptoms and cognitive deficits in pediatric populations. Most evidence indicates moderate improvements in executive functions, such as response inhibition and working memory, particularly with high-frequency rTMS targeting the DLPFC.

Several studies have examined the cognitive effects of highfrequency rTMS. A 2022 clinical trial conducted by Nagy et al. [70] reported that 15 sessions of rTMS applied to the right DLPFC significantly ameliorated inattention and overall ADHD symptom severity in children when combined with atomoxetine compared with atomoxetine monotherapy. These improvements persisted during a one month post-intervention follow-up period, suggesting that rTMS can elicit sustained therapeutic effects when consistently administered. In 2021, Westwood et al. [71] observed moderate enhancements in executive functions, including working memory and response inhibition, reinforcing the hypothesis that the DLPFC plays a pivotal role in cognitive enhancement in ADHD via TMS. In addition to cognitive improvements, some studies have evaluated the direct effects of rTMS on core ADHD symptoms. In one study, rTMS applied to the left DLPFC in children with ADHD resulted in significant reductions in parent-reported hyperactivity and impulsivity. Overall, TMS appears safe for pediatric patients with ADHD. In 2021, Westwood et al. [71] noted that side effects, such as scalp discomfort, headache, and fatigue, were mild and transient, consistent with the side effect profile observed in adult populations. No severe adverse effects were reported in the reviewed studies, and rTMS appeared to be well-tolerated across different pediatric age groups. In a cohort of >800 typically developing children and >300 neurologically impaired children, TMS was associated with favorable safety and tolerability outcomes, with no reports of hearing loss. The use of singleor paired-pulse TMS in pediatric populations, including children with epilepsy or cerebral palsy, did not induce seizures, confirming its safety in children >2 years [72]. A systematic review by Masuda et al. [73] analyzed the clinical effectiveness of rTMS in treating neurodevelopmental disorders, including ASD, tic disorder, and ADHD, in children and adolescents. According to this review, studies conducted by Gómez et al. [74] and Weaver et al. [75] employed rTMS as a treatment modality for ADHD in pediatric and adolescent populations (aged 7–12 years and 14–21 years, respectively). Despite methodological differences in evaluation approaches, both studies demonstrated improvements in behavioral rating scores following rTMS intervention in children with ADHD. A study has underscored the importance of the DLPFC in the pathophysiology of ADHD, as corroborated by functional magnetic resonance imaging findings. The results of these trials further support the role of DLPFC modulation in the treatment of ADHD. Low-frequency rTMS applied to the left DLPFC and high-frequency rTMS applied to the right DLPFC improved symptoms of inattention, hyperactivity, and impulsivity in test participants [74,75].

However, the outcomes of broader ADHD symptoms, such as inattention and hyperactivity, have been inconsistent across studies. Rubio et al. [44] reviewed the use of non-invasive brain stimulation techniques, including TMS and tDCS, with respect to their diagnostic and therapeutic applications, as well as the safety and ethical considerations of their use in pediatric patients with ADHD. This review reached a similar conclusion, noting that the current body of literature contains a limited number of exploratory studies investigating the therapeutic efficacy of TMS in pediatric and adolescent ADHD. Weaver et al. [75] conducted a randomized, shamcontrolled crossover trial to assess the efficacy and safety of TMS in the treatment of ADHD. Six of nine participants were aged ≤18 years, and all were diagnosed according to the DSM-IV-TR criteria. The study included a screening phase, followed by two treatment phases (active and sham), each lasting two weeks with a one-week washout period between them. TMS was administered to the right DLPFC at 10 Hz and 100% of the motor threshold, with five sessions per week for 10 sessions. Primary and secondary outcomes were evaluated using the Clinical Global Impressions-Improvement and ADHD-IV scales. Although improvements were observed across both treatment phases, no significant differences were detected between the active and sham treatments, making it difficult to draw definitive conclusions regarding the efficacy of TMS. However, TMS was deemed safe, and no serious adverse events were reported.

Neuromodulation techniques, including neurofeedback, tDCS, and TMS, offer distinct mechanisms for managing core ADHD symptoms and cognitive deficits. Neurofeedback shows efficacy, especially when combined with standard treatments, in promoting sustained symptom control and may serve as an alternative for children who are intolerant to or unsuitable for long-term pharmacotherapy. Although tDCS remains in the exploratory stages, it demonstrates moderate effects in reducing ADHD symptoms, particularly in terms of attention and impulsivity. Further studies are needed to establish standardized protocols for pediatric use. Furthermore, TMS outcomes are variable; high-frequency stimulation targeting areas, such as the DLPFC shows potential cognitive benefits, although more trials are needed to confirm these effects.

Neuromodulation for ADHD presents challenges, including a lack of standardized protocols, limited pediatric studies, safety concerns, high costs, and limited accessibility. However, opportunities exist for advancing technologies, such as personalized treatments with biomarkers, artificial intelligence-driven protocol optimization, and wearable devices, which can enhance accessibility and effectiveness. Collaborative studies and expanded clinical trials are essential to overcome these barriers.

In summary, although neuromodulation presents challenges, it remains a promising adjunctive approach to address the limitations of pharmacotherapy and enables tailored ADHD treatment strategies. Further studies should focus on refining stimulation parameters, increasing study sizes, and employing rigorous methodologies to integrate neuromodulation into standard ADHD care for children and adolescents.

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The datasets generated or analyzed during the study are available from the corresponding author on reasonable request.

The authors have no potential conflicts of interest to disclose.

Conceptualization: Jun Won Kim, Chan-Mo Yang. Formal analysis: Jun Won Kim, Chan-Mo Yang. Investigation: Jun Won Kim, Chan-Mo Yang. Methodology: Jun Won Kim, Chan-Mo Yang. Writing— original draft: Jun Won Kim, Chan-Mo Yang. Writing—review & editing: Jun Won Kim, Chan-Mo Yang.

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