The impact of prefrontal transcranial direct current stimulation (tDCS) on theory of mind, emotion regulation and emotional-behavioral functions in children with autism disorder: A randomized, sham-controlled, and parallel-group study

A network meta-analysis of non-invasive brain stimulation interventions for autism spectrum disorder: evidence from randomized controlled trials

The efficacy and acceptability of various non-invasive brain stimulation (NIBS) interventions for autism spectrum disorder remain unclear. We carried out a systematic review for randomized controlled trials (RCTs) regarding NIBS for reducing autistic symptoms (INPLASY202370003). Sixteen articles (N = 709) met the inclusion criteria for network meta-analysis. Effect sizes were reported as standardized mean differences (SMDs) or odds ratios with 95% confidence intervals (CIs). Fourteen active NIBS interventions, including transcranial direct current stimulation (tDCS), repetitive transcranial magnetic stimulation, and transcranial pulse stimulation were analyzed. Only anodal tDCS over the left dorsolateral prefrontal cortex paired with cathodal tDCS over an extracephalic location (atDCS_F3+ctDCS_E) significantly improved autistic symptoms compared to sham controls (SMD = -1.40, 95%CIs = -2.67 to -0.14). None of the NIBS interventions markedly improved social-communication symptoms or restricted/repetitive behaviors in autistic participants. Moreover, no active NIBS interventions exhibited significant dropout rate differences compared to sham controls, and no serious adverse events were reported for any intervention.

Effects of tDCS on emotion recognition and brain oscillations

INTRODUCTION

Emotion recognition, the ability to interpret the emotional state of individuals by looking at their facial expressions, is essential for healthy social interactions and communication. There is limited research on the effects of tDCS on emotion recognition in the literature. This study aimed to investigate the effects of anodal stimulation of the ventromedial prefrontal cortex (vmPFC), a key region for emotion recognition from facial expressions, on emotion recognition and brain oscillations.

METHOD

A single-blind randomized-controlled study was conducted with 54 healthy participants. Before and after brain stimulation emotion recognition tasks were administered and resting-state EEG were recorded. The changes in task performances and brain oscillations were analyzed using repeated-measures two-way ANOVA analysis.

RESULTS

There was no significant difference in the emotion recognition tasks between groups in pre-post measurements. The changes in delta, theta, alpha, beta and gamma frequency bands in the frontal, temporal, and posterio-occipital regions, which were determined as regions of interest in resting state EEG data before and after tDCS, were compared between groups. The results showed that there was a significant difference between groups only in delta frequency before and after tDCS in the frontal and temporal regions. While an increase in delta activity was observed in the experimental group in the frontal and temporal regions, a decrease was observed in the control group.

CONCLUSIONS

The tDCS may not have improved emotion recognition because it may not have had the desired effect on the vmPFC, which is in the lower part of the prefrontal lobe. The changes in EEG frequencies observed section tDCS may be similar to those seen in some pathological processes, which could explain the lack of improvement in emotion recognition. Future studies to be carried out for better understand this effect are important.

Neuroanatomical Predictors of Transcranial Direct Current Stimulation (tDCS)-Induced Modifications in Neurocognitive Task Performance in Typically Developing Individuals

Transcranial direct current stimulation (tDCS) is a noninvasive neuromodulation technique gaining more attention in neurodevelopmental disorders (NDDs). Due to the phenotypic heterogeneity of NDDs, tDCS is unlikely to be equally effective in all individuals. The present study aimed to establish neuroanatomical markers in typically developing (TD) individuals that may be used for the prediction of individual responses to tDCS. Fifty-seven male and female children received 2 mA anodal and sham tDCS, targeting the left dorsolateral prefrontal cortex (DLPFCleft), right inferior frontal gyrus, and bilateral temporoparietal junction. Response to tDCS was assessed based on task performance differences between anodal and sham tDCS in different neurocognitive tasks (N-back, flanker, Mooney faces detection, attentional emotional recognition task). Measures of cortical thickness (CT) and surface area (SA) were derived from 3 Tesla structural MRI scans. Associations between neuroanatomy and task performance were assessed using general linear models (GLM). Machine learning (ML) algorithms were employed to predict responses to tDCS. Vertex-wise estimates of SA were more closely linked to differences in task performance than measures of CT. Across ML algorithms, highest accuracies were observed for the prediction of N-back task performance differences following stimulation of the DLPFCleft, where 65% of behavioral variance was explained by variability in SA. Lower accuracies were observed for all other tasks and stimulated regions. This suggests that it may be possible to predict individual responses to tDCS for some behavioral measures and target regions. In the future, these models might be extended to predict treatment outcome in individuals with NDDs.

Adverse event monitoring and reporting in pediatric neuromodulatory studies: A systematic review

Neuromodulatory interventions are relatively novel and approaches to studying harms and tolerability have varied. Using a checklist based on guidelines from Good Clinical Practice and the Harms Extension of the CONSORT (Consolidated Standards of Reporting Trials) Statement, we identified how adverse events are measured, assessed, and reported in studies evaluating neuromodulation for the treatment of mental and neurodevelopmental disorders among children and adolescents. A systematic literature review identified 56 experimental and quasi-experimental studies evaluating transcranial magnetic stimulation (TMS), transcranial alternating (tACS) or direct (tDCS) current stimulation, transcranial pulse stimulation (TPS), and vagus or trigeminal nerve stimulation (VNS or TNS). For 22 studies (39%), the types of adverse events to be monitored were identified, and for 31 studies (55%), methods for collecting adverse event data were described. Methods for assessing adverse events were less commonly described with 23 studies (41%) having details on assessing event severity, and 11 studies (20%) having details on assessing event causality. Among 31 studies with reported results, headache, skin irritation, and general pain or discomfort were the most reported across studies. Seizure, untoward medical occurrences, and intracranial bleeding, edema, or other intracranial pathology were considered serious events, but these events were not reported as occurring in any results-based papers. Taken together, the findings from this review indicate that most studies of pediatric neuromodulatory interventions did not include descriptions of adverse event monitoring and evaluation. Comprehensive event monitoring and reporting across studies can significantly augment the current knowledge base.

Anodal transcranial direct-current stimulation and non-verbal intelligence in autism spectrum disorder: A randomized controlled trial

AIM

To understand the impact of anodal transcranial direct-current stimulation (tDCS) on non-verbal intelligence in high-functioning young adults with autism spectrum disorder (ASD).

METHOD

Thirty individuals with ASD were randomly divided into three groups receiving 2 mA, 20 minutes daily anodal tDCS for 10 sessions. Group A received 10 sham tDCS sessions, group B five real followed by five sham sessions, and group C received 10 real tDCS sessions. The total score of non-verbal intelligence was measured using the Test of Nonverbal Intelligence, Fourth Edition. The left dorsolateral prefrontal cortex (LDLPFC) was targeted using the International 10-20 electroencephalography system, and concurrent cognitive training was avoided.

RESULTS

Group C demonstrated a mean difference of 4.10 (95% confidence interval 1.41-6.79; p = 0.005) in Test of Nonverbal Intelligence scores compared with group A, with an effect size of 0.47. No significant differences were observed between groups A and B (p = 0.296), or between groups B and C (p = 0.140).

INTERPRETATION

Ten sessions of anodal tDCS to the LDLPFC led to improved non-verbal intelligence among individuals with ASD. These results emphasize the potential of tDCS as a discrete method for boosting cognitive abilities in the high-functioning population with ASD. Future studies with larger groups of participants and extended observation periods are necessary to validate these findings.

The use of noninvasive brain stimulation techniques in autism spectrum disorder

Noninvasive brain stimulation (NIBS) techniques, including repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), have recently emerged as alternative, nonpharmacological interventions for a variety of psychiatric, neurological, and neurodevelopmental conditions. NIBS is beginning to be applied in both research and clinical settings for the treatment of core and associated symptoms of autism spectrum disorder (ASD) including social communication deficits, restricted and repetitive behaviors, irritability, hyperactivity, depression and impairments in executive functioning and sensorimotor integration. Though there is much promise for these targeted device-based interventions, in other disorders (including adult major depressive disorder (MDD) and obsessive compulsive disorder (OCD) where rTMS is FDA cleared), data on the safety and efficacy of these interventions in individuals with ASD is limited especially in younger children when neurodevelopmental interventions typically begin. Most studies are open-label, small scale, and/or focused on a restricted subgroup of individuals with ASD. There is a need for larger, randomized controlled trials that incorporate neuroimaging in order to develop predictive biomarkers of treatment response and optimize treatment parameters. We contend that until such studies are conducted, we do not have adequate estimates of the safety and efficacy of NIBS interventions in children across the spectrum. Thus, broad off-label use of these techniques in this population is not supported by currently available evidence. Here we discuss the existing data on the use of NIBS to treat symptoms related to ASD and discuss future directions for the field.

Connectivity differences between inferior frontal gyrus and mentalizing network in autism as compared to developmental coordination disorder and non-autistic youth

Prior studies have compared neural connectivity during mentalizing tasks in autism (ASD) to non-autistic individuals and found reduced connectivity between the inferior frontal gyrus (IFG) and mentalizing regions. However, given that the IFG is involved in motor processing, and about 80% of autistic individuals have motor-related difficulties, it is necessary to explore if these differences are specific to ASD or instead similar across other developmental motor disorders, such as developmental coordination disorder (DCD). Participants (29 ASD, 20 DCD, 31 typically developing [TD]; ages 8-17) completed a mentalizing task in the fMRI scanner, where they were asked to think about why someone was performing an action. Results indicated that the ASD group, as compared to both TD and DCD groups, showed significant functional connectivity differences when mentalizing about other's actions. The left IFG seed revealed ASD connectivity differences with the: bilateral temporoparietal junction (TPJ), left insular cortex, and bilateral dorsolateral prefrontal cortex (DLPFC). Connectivity differences using the right IFG seed revealed ASD differences in the: left insula, and right DLPFC. These results indicate that connectivity differences between the IFG, mentalizing regions, emotion and motor processing regions are specific to ASD and not a result of potentially co-occurring motor differences.

Non-invasive brain stimulation for patient with autism: a systematic review and meta-analysis

Objective

To comprehensively evaluate the efficacy of non-invasive brain stimulation (NIBS) in patients with autism spectrum disorder (ASD) in randomized controlled trials (RCT), providing a reference for future research on the same topic.

Methods

Five databases were searched (Pubmed, Web of Science, Medline, Embase, and Cochrane library) and tracked relevant references, Meta-analysis was performed using RevMan 5.3 software.

Results

Twenty-two references (829 participants) were included. The results of the meta-analysis showed that NIBS had positive effects on repetitive and stereotypical behaviors, cognitive function, and executive function in autistic patients. Most of the included studies had a moderate to high risk of bias, Mainly because of the lack of blinding of subjects and assessors to treatment assignment, as well as the lack of continuous observation of treatment effects.

Conclusion

Available evidence supports an improvement in some aspects of NIBS in patients with ASD. However, due to the quality of the original studies and significant publication bias, this evidence must be treated with caution. Further large multicenter randomized double-blind controlled trials and appropriate follow-up observations are needed to further evaluate the specific efficacy of NIBS in patients with ASD.

Mentalising and depression: a mini-review on behavior, neural substrates, and treatment options

Major depression is one of the most common mental disorders, affecting millions of people around the globe. In recent years, researchers increasingly investigated social cognition in depression and discovered pronounced alterations. A special focus has been put on mentalising or Theory of Mind, the ability to recognize and understand another person's thoughts and feelings. While there is behavioral evidence for deficits in this ability in patients with depression as well as specialized therapeutic interventions, the neuroscientific substrates are only beginning to be understood. In this mini-review, we take a social neuroscience perspective to analyse the importance of altered mentalising in depression and whether it can help to understand the origins and perpetuation of the disorder. We will put a special focus on treatment options and corresponding neural changes to identify relevant paths for future (neuroscientific) research.

A bibliometric analysis of global research status and trends in neuromodulation techniques in the treatment of autism spectrum disorder

BACKGROUND

Autism spectrum disorder (ASD) is a neurodevelopmental disease which has risen to become the main cause of childhood disability, placing a heavy burden on families and society. To date, the treatment of patients with ASD remains a complicated problem, for which neuromodulation techniques are a promising solution. This study analyzed the global research situation of neuromodulation techniques in the treatment of ASD from 1992 to 2022, aiming to explore the global research status and frontier trends in this field.

METHODS

The Web of Science (WoS) was searched for literature related to neuromodulation techniques for ASD from 1992 to October 2022. A knowledge atlas to analyze collaboration among countries, institutions, authors, publishing journals, reference co-citation patterns, keyword co-occurrence, keyword clustering, and burst keywords was constructed using Rstudio software, CiteSpace, and VOSviewer.

RESULTS

In total, 392 publications related to the treatment of ASD using neuromodulation techniques were included. Despite some fluctuations, the number of publications in this field has shown a growing trend in recent years. The United States and Deakin University are the leading country and institution in this field, respectively. The greatest contributing authors are Peter G Enticott, Manuel F Casanova, and Paul B Fitzgerald et al. The most prolific and cited journal is Brain Stimulation and the most commonly co-cited journal is The Journal of Autism and Developmental Disorders. The most frequently cited article was that of Simone Rossi (Safety, ethical considerations, and application guidelines for the use of transverse magnetic stimulation in clinical practice and research, 2009). "Obsessive-compulsive disorder," "transcranial direct current stimulation," "working memory," "double blind" and "adolescent" were identified as hotspots and frontier trends of neuromodulation techniques in the treatment of ASD.

CONCLUSION

The application of neuromodulation techniques for ASD has attracted the attention of researchers worldwide. Restoring the social ability and improving the comorbid symptoms in autistic children and adults have always been the focus of research. Neuromodulation techniques have demonstrated significant advantages and effects on these issues. Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) are new therapeutic methods introduced in recent years, and are also directions for further exploration.

Effects of transcranial direct current stimulation in children and young people with psychiatric disorders: a systematic review

Transcranial direct current stimulation (tDCS) has demonstrated benefits in adults with various psychiatric disorders, but its clinical utility in children and young people (CYP) remains unclear. This PRISMA systematic review used published and ongoing studies to examine the effects of tDCS on disorder-specific symptoms, mood and neurocognition in CYP with psychiatric disorders. We searched Medline via PubMed, Embase, PsychINFO via OVID, and Clinicaltrials.gov up to December 2022. Eligible studies involved multiple session (i.e., treatment) tDCS in CYP (≤ 25 years old) with psychiatric disorders. Two independent raters assessed the eligibility of studies and extracted data using a custom-built form. Of 33 eligible studies (participant N = 517), the majority (n = 27) reported an improvement in at least one outcome measure of disorder-specific symptoms. Few studies (n = 13) examined tDCS effects on mood and/or neurocognition, but findings were mainly positive. Overall, tDCS was well tolerated with minimal side effects. Of 11 eligible ongoing studies, many are sham-controlled RCTs (n = 9) with better blinding techniques and a larger estimated participant enrolment (M = 79.7; range 15-172) than published studies. Although encouraging, the evidence to date is insufficient to firmly conclude that tDCS can improve clinical symptoms, mood, or cognition in CYP with psychiatric disorders. Ongoing studies appear of improved methodological quality; however, future studies should broaden outcome measures to more comprehensively assess the effects of tDCS and develop dosage guidance (i.e., treatment regimens).