Abnormal Cortical Plasticity in Youth with Autism Spectrum Disorder: A Transcranial Magnetic Stimulation Case-Control Pilot Study

Transcranial Magnetic Stimulation Across the Lifespan: Impact of Developmental and Degenerative Processes

Transcranial magnetic stimulation (TMS) has emerged as a pivotal noninvasive technique for investigating cortical excitability and plasticity across the lifespan, offering valuable insights into neurodevelopmental and neurodegenerative processes. In this review, we explore the impact of TMS applications on our understanding of normal development, healthy aging, neurodevelopmental disorders, and adult-onset neurodegenerative diseases. By presenting key developmental milestones and age-related changes in TMS measures, we provide a foundation for understanding the maturation of neurotransmitter systems and the trajectory of cognitive functions throughout the lifespan. Building on this foundation, the paper delves into the pathophysiology of neurodevelopmental disorders, including autism spectrum disorder, attention-deficit/hyperactivity disorder, Tourette syndrome, and adolescent depression. Highlighting recent findings on altered neurotransmitter circuits and dysfunctional cortical plasticity, we underscore the potential of TMS as a valuable tool for unraveling underlying mechanisms and informing future therapeutic interventions. We also review the emerging role of TMS in investigating and treating the most common adult-onset neurodegenerative disorders and late-onset depression. By outlining the therapeutic applications of noninvasive brain stimulation techniques in these disorders, we discuss the growing body of evidence supporting their use as therapeutic tools for symptom management and potentially slowing disease progression. The insights gained from TMS studies have advanced our understanding of the underlying mechanisms in both healthy and disease states, ultimately informing the development of more targeted diagnostic and therapeutic strategies for a wide range of neuropsychiatric conditions.

Treatment Response of Transcranial Magnetic Stimulation in Intellectually Capable Youth and Young Adults with Autism Spectrum Disorder: A Systematic Review and Meta-Analysis

To examine current clinical research on the use of transcranial magnetic stimulation (TMS) in the treatment of pediatric and young adult autism spectrum disorder in intellectually capable persons (IC-ASD). We searched peer-reviewed international literature to identify clinical trials investigating TMS as a treatment for behavioral and cognitive symptoms of IC-ASD. We identified sixteen studies and were able to conduct a meta-analysis on twelve of these studies. Seven were open-label or used neurotypical controls for baseline cognitive data, and nine were controlled trials. In the latter, waitlist control groups were often used over sham TMS. Only one study conducted a randomized, parallel, double-blind, and sham controlled trial. Favorable safety data was reported in low frequency repetitive TMS, high frequency repetitive TMS, and intermittent theta burst studies. Compared to TMS research of other neuropsychiatric conditions, significantly lower total TMS pulses were delivered in treatment and neuronavigation was not regularly utilized. Quantitatively, our multivariate meta-analysis results report improvement in cognitive outcomes (pooled Hedges' g = 0.735, 95% CI = 0.242, 1.228; p = 0.009) and primarily Criterion B symptomology of IC-ASD (pooled Hedges' g = 0.435, 95% CI = 0.359, 0.511; p < 0.001) with low frequency repetitive TMS to the dorsolateral prefrontal cortex. The results of our systematic review and meta-analysis data indicate that TMS may offer a promising and safe treatment option for pediatric and young adult patients with IC-ASD. However, future work should include use of neuronavigation software, theta burst protocols, targeting of various brain regions, and robust study design before clinical recommendations can be made.

A family study of symbolic learning and synaptic plasticity in autism spectrum disorder

The current study presents a male with autism spectrum disorder (ASD) and a 3q29 deletion, and three healthy first-degree relatives. Our magnetic resonance imaging (MRI) dataset included a healthy control subset. We describe a comprehensive multimodal approach, including equivalence class formation, neurocognitive testing, MRI, and electroencephalography (EEG)-based cortical plasticity, which can provide new insights into socio-communicative and learning impairments and neural underpinnings in ASD. On neurocognitive testing, the proband showed reduced processing speed, attending behavior, and executive function. He required more training trials in equivalence class training compared with family members and exhibited impaired priming of words compared with priming with images. The proband had smaller intracranial volume and surface area and a larger visual evoked potential (VEP) C1 amplitude than family members and intact long-term potentiation (LTP)-like visual cortex plasticity. Together, these results suggest that 3q29 deletion-related ASD is associated with impaired problem-solving strategies in complex socio-communicative and learning tasks, smaller intracranial and surface area, altered VEP amplitude, and normal LTP-like visual cortex plasticity. Further studies are needed to clarify whether this multimodal approach can be used to identify ASD subgroups with distinct neurobiological alterations and to uncover mechanisms underlying socio-communicative and learning impairments. Lay Summary: We studied learning, brain activity, and brain structure in a person with autism and a genetic aberration, and his close relatives. Compared with relatives, the person with autism required more training for learning, and visual learning was better than verbal learning. This person had some changes in the activity of the visual cortex, and the size and the surface area of the brain were reduced. Knowledge about learning and brain mechanisms is valuable for the development of training programs for individuals with autism.

A Systematic Review of the Safety and Tolerability of Theta Burst Stimulation in Children and Adolescents

OBJECTIVES

Theta burst stimulation (TBS) is often used in clinical practice and research protocols for adults with neuropsychiatric disorders. There are substantial knowledge gaps related to the application of TBS in children and adolescents. This systematic review examined the safety and tolerability of TBS in children and adolescents.

MATERIALS AND METHODS

A systematic review of human TBS studies in children and adolescents was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The following inclusion criteria were applied: 1) articles in English language only; 2) studies that included child and adolescent participants (up to 21 years of age); 3) studies that administered intermittent TBS or continuous TBS or both to participants; 4) studies that had an outcome measure; and 5) availability of full text material. The primary outcome measures were tolerability and safety. When feasible, the clinical effects were reviewed.

RESULTS

Twenty relevant articles met the criteria for inclusion. The reported adverse events were mild and similar to what is noted in adult studies. The most common symptom was headache. One case report described a seizure induced by TBS. Collectively, the studies were heterogeneous but the methodologic quality of randomized trials was high.

CONCLUSIONS

TBS interventions in children may have similar safety, tolerability, and feasibility as compared to adults. However, long-term, follow-up studies of TBS are lacking. Future dose-ranging studies with systematic assessment of adverse events will be important in the translation of findings with TBS from adults to youth.

Prevalence of Adverse Effects Associated With Transcranial Magnetic Stimulation for Autism Spectrum Disorder: A Systematic Review and Meta-Analysis

Background

A growing number of studies have suggested that transcranial magnetic stimulation (TMS) may represent a novel technique with both investigative and therapeutic potential for autism spectrum disorder (ASD). However, a full spectrum of the adverse effects (AEs) of TMS used in ASD has not been specifically and systematically evaluated.

Objective

This systematic review and meta-analysis was to assess the prevalence of AEs related to TMS in ASD and to further explore the potentially related factors on the AEs.

Methods

A systematic literature research of articles published before 31 December 2020 was conducted in the databases of PubMed, Embase, Cochrane Library, Ovid, PsycINFO, Chinese National Knowledge Infrastructure (CNKI), Chongqing VIP, and WANFANG DATA. AEs reported in the studies were carefully examined and synthesized to understand the safety and tolerability of TMS among ASD. Then, subgroup and sensitivity analyses were performed to examine the potentially related factors on the AEs. PROSPERO registration number: CRD42021239827.

Results

Eleven studies were included in the meta-analysis. The pooled prevalence with 95% confidence interval (CI) of AEs was calculated (overall AEs: 25%, 95% CI 18-33%; headache: 10%, 95% CI 3-19%; facial discomfort: 15%, 95% CI 4-29%; irritability 21%, 95% CI 8-37%; pain at the application site: 6%, 95% CI 0-19%; headedness or dizziness: 8%, 95% CI 0-23%). All reported AEs were mild and transient with relatively few serious AEs and can be resolved after having a rest or medication. In addition, the following variables showed no significant change in overall prevalence of AEs: the purpose of using TMS, mean age of participants, whether the stimulation site was dorsolateral pre-frontal cortex (DLPFC), intensity of TMS, and the number of stimulation sessions.

Conclusion

The overall prevalence of reported AEs of TMS among ASD was 25%. No identified ASD-specific risk factors for TMS-induced AEs were found. Further studies are needed to clarify the variation in the prevalence.

Systematic Review Registration

www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=239827, PROSPERO, identifier: CRD42021239827.

Use of Repetitive Transcranial Magnetic Stimulation in Child Psychiatry

OBJECTIVE

Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive diagnostic and therapeutic technique that has showed benefits in various psychiatric disorders. Although there is a large body of literature available on its use in adult populations, existing research in pediatric populations is very limited. Current research has primarily focused on its use in adolescent treatment-resistant depression. However, recently, rTMS has gained attention among researchers to find its utility in other neuropsychiatric disorders, such as autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), obsessive compulsive disorder (OCD), tics, and psychosis. There is a lack of systematic data on the safety of rTMS in children and adolescents. The aim of this article was to present an overview of the existing literature on the use of rTMS in children and adolescents and examine the relevant safety considerations.

METHODS

We conducted a literature review of the English literature in PubMed on TMS in children and adolescents, using comprehensive search terms and expanding our review to include sources cited by these reports. We reviewed the application of rTMS in psychiatric disorders in the pediatric population.

RESULTS

rTMS has been used for depression and anxiety disorders, OCD, ADHD, Tourette syndrome/tics, ASD, and schizophrenia, with variable results.

CONCLUSION

rTMS is a promising treatment in children and adolescents with psychiatric disorders, although larger, sham-controlled, randomized, controlled trials (RCTs) will be required to definitely demonstrate efficacy, as well as to support a safety profile.

Biomarkers Obtained by Transcranial Magnetic Stimulation in Neurodevelopmental Disorders

SUMMARY

Transcranial magnetic stimulation (TMS) is a method for focal brain stimulation that is based on the principle of electromagnetic induction where small intracranial electric currents are generated by a powerful fluctuating magnetic field. Over the past three decades, TMS has shown promise in the diagnosis, monitoring, and treatment of neurological and psychiatric disorders in adults. However, the use of TMS in children has been more limited. We provide a brief introduction to the TMS technique; common TMS protocols including single-pulse TMS, paired-pulse TMS, paired associative stimulation, and repetitive TMS; and relevant TMS-derived neurophysiological measurements including resting and active motor threshold, cortical silent period, paired-pulse TMS measures of intracortical inhibition and facilitation, and plasticity metrics after repetitive TMS. We then discuss the biomarker applications of TMS in a few representative neurodevelopmental disorders including autism spectrum disorder, fragile X syndrome, attention-deficit hyperactivity disorder, Tourette syndrome, and developmental stuttering.

What Is Social about Autism? The Role of Allostasis-Driven Learning

Scientific research on neuro-cognitive mechanisms of autism often focuses on circuits that support social functioning. However, autism is a heterogeneous developmental variation in multiple domains, including social communication, but also language, cognition, and sensory-motor control. This suggests that the underlying mechanisms of autism share a domain-general foundation that impacts all of these processes. In this Perspective Review, we propose that autism is not a social deficit that results from an atypical "social brain". Instead, typical social development relies on learning. In social animals, infants depend on their caregivers for survival, which makes social information vitally salient. The infant must learn to socially interact in order to survive and develop, and the most prominent learning in early life is crafted by social interactions. Therefore, the most prominent outcome of a learning variation is atypical social development. To support the hypothesis that autism results from a variation in learning, we first review evidence from neuroscience and developmental science, demonstrating that typical social development depends on two domain-general processes that determine learning: (a) motivation, guided by allostatic regulation of the internal milieu; and (b) multi-modal associations, determined by the statistical regularities of the external milieu. These two processes are basic ingredients of typical development because they determine allostasis-driven learning of the social environment. We then review evidence showing that allostasis and learning are affected among individuals with autism, both neurally and behaviorally. We conclude by proposing a novel domain-general framework that emphasizes allostasis-driven learning as a key process underlying autism. Guided by allostasis, humans learn to become social, therefore, the atypical social profile seen in autism can reflect a domain-general variation in allostasis-driven learning. This domain-general view raises novel research questions in both basic and clinical research and points to targets for clinical intervention that can lower the age of diagnosis and improve the well-being of individuals with autism.

Connectivity alterations in autism reflect functional idiosyncrasy

Autism spectrum disorder (ASD) is commonly understood as an alteration of brain networks, yet case-control analyses against typically-developing controls (TD) have yielded inconsistent results. Here, we devised a novel approach to profile the inter-individual variability in functional network organization and tested whether such idiosyncrasy contributes to connectivity alterations in ASD. Studying a multi-centric dataset with 157 ASD and 172 TD, we obtained robust evidence for increased idiosyncrasy in ASD relative to TD in default mode, somatomotor and attention networks, but also reduced idiosyncrasy in lateral temporal cortices. Idiosyncrasy increased with age and significantly correlated with symptom severity in ASD. Furthermore, while patterns of functional idiosyncrasy were not correlated with ASD-related cortical thickness alterations, they co-localized with the expression patterns of ASD risk genes. Notably, we could demonstrate that patterns of atypical idiosyncrasy in ASD closely overlapped with connectivity alterations that are measurable with conventional case-control designs and may, thus, be a principal driver of inconsistency in the autism connectomics literature. These findings support important interactions between inter-individual heterogeneity in autism and functional signatures. Our findings provide novel biomarkers to study atypical brain development and may consolidate prior research findings on the variable nature of connectome level anomalies in autism.

An Updated Review of Tuberous Sclerosis Complex-Associated Autism Spectrum Disorder

Tuberous sclerosis complex (TSC) is a neurocutaneous disorder caused by mutations of either the TSC1 or TSC2 gene. Various neuropsychiatric features, including autism, are prevalent in TSC. Recently, significant progress has been possible with the prospective calculation of the prevalence of autism in TSC, identification of early clinical and neurophysiological biomarkers to predict autism, and investigation of different therapies to prevent autism in this high-risk population. The author provides a narrative review of recent findings related to biomarkers for diagnosis of autism in TSC, as well as recent studies related to the management of TSC-associated autism. Further sophisticated modeling and analysis are required to understand the role of different models-tuber models, seizures and related neurophysiological factors models, genotype models, and brain connectivity models-to unravel the neurobiological basis of autism in TSC. Early neuropsychologic assessments may be beneficial in this high-risk group. Targeted intervention to improve visual skill, cognition, and fine motor skills with later addition of social skill training can be helpful. Multicenter, prospective studies are ongoing to identify if presymptomatic treatment with vigabatrin in patients with TSC can improve outcomes, including autism. Several studies indicated reasonable safety of everolimus in young children, and its potential application in high-risk infants with TSC, before the closure of the temporal window of permanent changes, maybe undertaken shortly.

Motor potential evoked by transcranial magnetic stimulation depends on the placement protocol of recording electrodes: a pilot study

OBJECTIVE

There seems to be no consensus in the literature regarding the protocol of surface electromyography (sEMG) electrode placement for recording motor evoked potentials (MEP) in transcranial magnetic stimulation (TMS) applications. Thus, the aim of this study was to investigate the effect on the MEP amplitude bytwo different protocols for electrode placement.

METHODS

sEMG electrodes were placed on three upper arm muscles (biceps brachii, flexor carpi radialis, and flexor pollicis brevis) of six right-handed subjects following two different protocols (1 and 2), which varied according to the interelectrode distance and location relative to the muscle. TMS pulses were applied to the hotspot of biceps brachii, while sEMGwas recorded from the two protocols and for each muscle simultaneously.

MAIN RESULTS

Greater MEP amplitudes were obtained for Protocol 1 compared to Protocol 2 (P < 0.05).

SIGNIFICANCE

Different electrode placement protocols may result in distinct MEP amplitudes, which should be taken into account when adjusting the intensity on single and repetitive TMS sessions.

Continuous Theta-Burst Stimulation in Children With High-Functioning Autism Spectrum Disorder and Typically Developing Children

Objectives: A neurophysiologic biomarker for autism spectrum disorder (ASD) is highly desirable and can improve diagnosis, monitoring, and assessment of therapeutic response among children with ASD. We investigated the utility of continuous theta-burst stimulation (cTBS) applied to the motor cortex (M1) as a biomarker for children and adolescents with high-functioning (HF) ASD compared to their age- and gender-matched typically developing (TD) controls. We also compared the developmental trajectory of long-term depression- (LTD-) like plasticity in the two groups. Finally, we explored the influence of a common brain-derived neurotrophic factor (BDNF) polymorphism on cTBS aftereffects in a subset of the ASD group. Methods: Twenty-nine children and adolescents (age range 10-16) in ASD (n = 11) and TD (n = 18) groups underwent M1 cTBS. Changes in MEP amplitude at 5-60 min post-cTBS and their cumulative measures in each group were calculated. We also assessed the relationship between age and maximum cTBS-induced MEP suppression (ΔMEP_Max) in each group. Finally, we compared cTBS aftereffects in BDNF Val/Val (n = 4) and Val/Met (n = 4) ASD participants. Results: Cumulative cTBS aftereffects were significantly more facilitatory in the ASD group than in the TD group (P _FDR's < 0.03). ΔMEP_Max was negatively correlated with age in the ASD group (r = -0.67, P = 0.025), but not in the TD group (r = -0.12, P = 0.65). Cumulative cTBS aftereffects were not significantly different between the two BDNF subgroups (P-values > 0.18). Conclusions: The results support the utility of cTBS measures of cortical plasticity as a biomarker for children and adolescents with HF-ASD and an aberrant developmental trajectory of LTD-like plasticity in ASD.

Motor cortical plasticity in schizophrenia: A meta-analysis of Transcranial Magnetic Stimulation - Electromyography studies

BACKGROUND

Several lines of investigations converge upon aberrant synaptic plasticity as a potential pathophysiological characteristic of schizophrenia. In vivo experiments using neuromodulatory perturbation techniques like Transcranial Magnetic and Direct Current Stimulation (TMS & tDCS) have been increasingly used to measure 'motor cortical plasticity' in schizophrenia. A systematic quantification of cortical plasticity and its moderators in schizophrenia is however lacking.

METHOD

The PubMed/MEDLINE database was searched for studies up to December 31st, 2017 that examined case-control experiments comparing neuromodulation following single-session of TMS or tDCS. The primary outcome was the standardized mean difference for differential changes in motor evoked potential (MEP) amplitudes measured with single-pulse TMS (MEP Δ) between patients and healthy subjects following TMS or tDCS. After examining heterogeneity, meta-analyses were performed using fixed effects models.

RESULTS

A total of 16 datasets comparing cortical plasticity (MEP Δ) between 189 schizophrenia patients and 187 healthy controls were included in the meta-analysis. Patients demonstrated diminished MEP Δ with effect sizes (Cohen's d) ranging from 0.66 (LTP-like plasticity) to 0.68 (LTD-like plasticity). Heterosynaptic plasticity studies demonstrated a greater effect size (0.79) compared to homosynaptic plasticity studies (0.62), though not significant (P = 0.43). Clinical, perturbation protocol- and measurement-related factors, and study quality did not significantly moderate the aberrant plasticity demonstrated in schizophrenia.

CONCLUSIONS

Schizophrenia patients demonstrate diminished LTP- and LTD-like motor cortical plasticity, which is not influenced by the various clinical and experimental protocol related confounders. These consistent findings should encourage the use of perturbation-based biomarkers to characterize illness trajectories and treatment response.

Motor cortex excitability and inhibitory imbalance in autism spectrum disorder assessed with transcranial magnetic stimulation: a systematic review

Cortical excitation/inhibition (E/I) imbalances contribute to various clinical symptoms observed in autism spectrum disorder (ASD). However, the detailed pathophysiologic underpinning of E/I imbalance remains uncertain. Transcranial magnetic stimulation (TMS) motor-evoked potentials (MEP) are a non-invasive tool for examining cortical inhibition in ASD. Here, we conducted a systematic review on TMS neurophysiology in motor cortex (M1) such as MEPs and short-interval intracortical inhibition (SICI) between individuals with ASD and controls. Out of 538 initial records, we identified six articles. Five studies measured MEP, where four studies measured SICI. There were no differences in MEP amplitudes between the two groups, whereas SICI was likely to be reduced in individuals with ASD compared with controls. Notably, SICI largely reflects GABA(A) receptor-mediated function. Conversely, other magnetic resonance spectroscopy and postmortem methodologies assess GABA levels. The present review demonstrated that there may be neurophysiological deficits in GABA receptor-mediated function in ASD. In conclusion, reduced GABAergic function in the neural circuits could underlie the E/I imbalance in ASD, which may be related to the pathophysiology of clinical symptoms of ASD. Therefore, a novel treatment that targets the neural circuits related to GABA(A) receptor-mediated function in regions involved in the pathophysiology of ASD may be promising.

Transcranial Magnetic Stimulation in Conditions Other than Major Depressive Disorder

Transcranial magnetic stimulation (TMS) is a treatment approved by the Food and Drug Administration for major depressive disorder (MDD). TMS is a neuromodulation technique that works by creating a focal magnetic field that induces a small electric current. Compared with other neuromodulation techniques, TMS is a noninvasive treatment modality that is generally well-tolerated. Because of the success of TMS in treating depression, there has been interest in applications for other neuropsychiatric diseases. The purpose of this article was to review potential uses for TMS for children and adolescents in conditions other than MDD.

Impact of different intensities of intermittent theta burst stimulation on the cortical properties during TMS-EEG and working memory performance

Intermittent theta burst stimulation (iTBS) is a noninvasive brain stimulation technique capable of increasing cortical excitability beyond the stimulation period. Due to the rapid induction of modulatory effects, prefrontal application of iTBS is gaining popularity as a therapeutic tool for psychiatric disorders such as depression. In an attempt to increase efficacy, higher than conventional intensities are currently being applied. The assumption that this increases neuromodulatory may be mechanistically false for iTBS. This study examined the influence of intensity on the neurophysiological and behavioural effects of iTBS in the prefrontal cortex. Sixteen healthy participants received iTBS over prefrontal cortex at either 50, 75 or 100% resting motor threshold in separate sessions. Single-pulse TMS and concurrent electroencephalography (EEG) was used to assess changes in cortical reactivity measured as TMS-evoked potentials and oscillations. The n-back task was used to assess changes in working memory performance. The data can be summarised as an inverse U-shape relationship between intensity and iTBS plastic effects, where 75% iTBS yielded the largest neurophysiological changes. Improvement in reaction time in the 3-back task was supported by the change in alpha power, however, comparison between conditions revealed no significant differences. The assumption that higher intensity results in greater neuromodulatory effects may be false, at least in healthy individuals, and should be carefully considered for clinical populations. Neurophysiological changes associated with working memory following iTBS suggest functional relevance. However, the effects of different intensities on behavioural performance remain elusive in the present healthy sample.

Application of Linear Mixed-Effects Models in Human Neuroscience Research: A Comparison with Pearson Correlation in Two Auditory Electrophysiology Studies

Neurophysiological studies are often designed to examine relationships between measures from different testing conditions, time points, or analysis techniques within the same group of participants. Appropriate statistical techniques that can take into account repeated measures and multivariate predictor variables are integral and essential to successful data analysis and interpretation. This work implements and compares conventional Pearson correlations and linear mixed-effects (LME) regression models using data from two recently published auditory electrophysiology studies. For the specific research questions in both studies, the Pearson correlation test is inappropriate for determining strengths between the behavioral responses for speech-in-noise recognition and the multiple neurophysiological measures as the neural responses across listening conditions were simply treated as independent measures. In contrast, the LME models allow a systematic approach to incorporate both fixed-effect and random-effect terms to deal with the categorical grouping factor of listening conditions, between-subject baseline differences in the multiple measures, and the correlational structure among the predictor variables. Together, the comparative data demonstrate the advantages as well as the necessity to apply mixed-effects models to properly account for the built-in relationships among the multiple predictor variables, which has important implications for proper statistical modeling and interpretation of human behavior in terms of neural correlates and biomarkers.

Transcranial Magnetic and Direct Current Stimulation in Children

Promising results in adult neurologic and psychiatric disorders are driving active research into transcranial brain stimulation techniques, particularly transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), in childhood and adolescent syndromes. TMS has realistic utility as an experimental tool tested in a range of pediatric neuropathologies such as perinatal stroke, depression, Tourette syndrome, and autism spectrum disorder (ASD). tDCS has also been tested as a treatment for a number of pediatric neurologic conditions, including ASD, attention-deficit/hyperactivity disorder, epilepsy, and cerebral palsy. Here, we complement recent reviews with an update of published TMS and tDCS results in children, and discuss developmental neuroscience considerations that should inform pediatric transcranial stimulation.

Pediatric Neuromodulation Comes of Age

This special issue surveys recent work and underscores the challenges of psychiatric brain stimulation research with child and adolescent populations. The field of child and adolescent psychopharmacology is replete with examples of potential pitfalls in the assumption that "children are little adults." Arguably, younger age portends more neurobiological and descriptive heterogeneity in research pursuits and clinical practice. For existing brain stimulation modalities, there are a paucity of translational models to design studies for youth and no well-studied dosing schemes. The long-term positive and negative effects of neuromodulation interventions in youth are unknown. Inherent pragmatic and ethical limitations often present barriers for participant recruitment and will necessitate innovative approaches to study design and team efforts. These challenges are not insurmountable, and sustained efforts will advance the growing field of pediatric neuromodulation.