Age-related differences in frontal lobe function in children with ADHD

Facial Affect Recognition and Executive Function Abnormalities in ADHD Subjects: An ERP Study

Attention-deficit/hyperactivity disorder (ADHD) affects approximately 12% of children worldwide. With a 50% chance of persistence into adulthood and associations with impairments in various domains, including social and emotional ones, early diagnosis is crucial. The exact neural substrates of ADHD are still unclear. This study aimed to reassess the behavioral and neural metrics of executive functions and neural substrates of facial affect recognition. A total of 117 ADHD patients and 183 healthy controls were evaluated by two Go/NoGo tasks: the classic visual continuous performance test and the emotional continuous performance test, which requires facial affect encoding. Group differences between ADHD subjects and healthy controls were assessed using analysis of covariance (ANCOVA), with age and sex included as covariates. Dependent variables comprised behavioral (number of omission and commission errors, reaction time, and reaction time variability) and neurophysiological measures (event-related potentials [ERPs]). As the main result, we identified significant differences between ADHD patients and healthy controls in all behavioral metrics, one neural marker of action inhibition (P3d) and the facial processing marker (N170). The differences were moderate-to-large when expressed as effect size measures in behavioral variables and small-to-moderate for neurophysiological variables. The small-to-moderate effect sizes obtained from the neurophysiological measures suggest that ERPs are insufficient as sole markers for effectively screening emotion and face processing abnormalities in ADHD.

Visualizing changes in cerebral hemodynamics in children with ADHD who have discontinued methylphenidate: A pilot study on using brain function for medication discontinuation decisions

OBJECTIVE

This study undertook neuropharmacological research on the clinical course of controlled medication discontinuation to guide practitioners who are considering stopping medications for youths with attention-deficit hyperactivity disorder (ADHD).

METHODS

This study analyzed the data for 14 ADHD children (12 male and 2 female) in two datasets: The children prescribed methylphenidate (MPH) were at an initial mean age of 7.5 years (SD = 1.70, range: 6-11) with a mean ADHD-Rating Score (ADHD-RS) of 26.6 (SD = 8.64, range 15-40). The children who discontinued MPH based on clinical judgment were at a mean age of 12.21 years (SD = 2.12, range: 8-15) with a mean ADHD-RS of 15.9 (SD = 6.86, range 5-27). The go/no-go task was used to assess response inhibition, while functional near-infrared spectroscopy (fNIRS) was used to measure cerebral hemodynamics. Oxygenated hemoglobin (Oxy-Hb) values from fNIRS data were analyzed for each subject, focusing on past and current measurements. Baseline was set at 10 s pre-task, with interval means from 4 to 24 s analyzed. One-sample t-tests were used to evaluate brain activity magnitude.

RESULTS

The results of the study demonstrate that the children who had discontinued the medication exhibited activation in specific brain regions including the frontopolar cortex and the right ventrolateral prefrontal cortex. Activation (t = 2.363, p = 0.034, Cohen's d = 0.632) was found especially in the right dorsolateral prefrontal cortex during the performance of the go/no-go task. These activated areas were consistent with those observed in a previous study comparing brain activity during a go/no-go task between children with ADHD and healthy children.

CONCLUSION

The present study showed differences in cerebral hemodynamics before and after discontinuation of MPH in ADHD children whose ADHD symptoms did not recur after MPH was discontinued. In the near future, further investigations that include control groups will be conducted to demonstrate the effects of MPH prior to discontinuation based on the changes in cerebral blood flow in the right prefrontal cortex, which is involved in behavioral inhibition, as observed in this study. This and future research will facilitate the development of criteria for discontinuing treatment.

Low-intensity transcranial ultrasound stimulation improves memory behavior in an ADHD rat model by modulating cortical functional network connectivity

Working memory in attention deficit hyperactivity disorder (ADHD) is closely related to cortical functional network connectivity (CFNC), such as abnormal connections between the frontal, temporal, occipital cortices and with other brain regions. Low-intensity transcranial ultrasound stimulation (TUS) has the advantages of non-invasiveness, high spatial resolution, and high penetration depth and can improve ADHD memory behavior. However, how it modulates CFNC in ADHD and the CFNC mechanism that improves working memory behavior in ADHD remain unclear. In this study, we observed working memory impairment in ADHD rats, establishing a corresponding relationship between changes in CFNCs and the behavioral state during the working memory task. Specifically, we noted abnormalities in the information transmission and processing capabilities of CFNC in ADHD rats while performing working memory tasks. These abnormalities manifested in the network integration ability of specific areas, as well as the information flow and functional differentiation of CFNC. Furthermore, our findings indicate that TUS effectively enhances the working memory ability of ADHD rats by modulating information transmission, processing, and integration capabilities, along with adjusting the information flow and functional differentiation of CFNC. Additionally, we explain the CFNC mechanism through which TUS improves working memory in ADHD. In summary, these findings suggest that CFNCs are important in working memory behaviors in ADHD.

Gray matter asymmetry alterations in children and adolescents with comorbid autism spectrum disorder and attention-deficit/hyperactivity disorder

Despite the high coexistence of autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) (ASD + ADHD), the underlying neurobiological basis of this disorder remains unclear. Altered brain structural asymmetries have been verified in ASD and ADHD, respectively, making brain asymmetry a candidate for characterizing this coexisting disorder. Here, we measured the gray matter (GM) volume asymmetry in ASD + ADHD versus ASD without ADHD (ASD-only), ADHD without ASD (ADHD-only), and typically developing controls (TDc). High-resolution T1-weighted data from 48 ASD + ADHD, 63 ASD-only, 32 ADHD-only, and 211 matched TDc were included in our study. We also assessed brain-behavior relationships and the effects of age on GM asymmetry. We found that there were both shared and disorder-specific GM volume asymmetry alterations in ASD + ADHD, ASD-only, and ADHD-only compared with TDc. This finding demonstrates that ASD + ADHD is neither an endophenocopy nor an additive pathology of ASD and ADHD, but an entirely different neuroanatomical pathology. In addition, ASD + ADHD displayed altered GM volume asymmetries in the prefrontal regions responsible for executive function and theory of mind compared with ASD-only. We also found significant effects of age on GM asymmetry. The present study may provide structural insights into the neural basis of ASD + ADHD.

Comparison of arterial spin labeled MRI (ASL MRI) between ADHD and control group (ages of 6-12)

This study utilized arterial spin labeling-magnetic resonance imaging (ASL-MRI) to explore the developmental trajectory of brain activity associated with attention deficit hyperactivity disorder (ADHD). Pulsed arterial spin labeling (ASL) data were acquired from 157 children with ADHD and 109 children in a control group, all aged 6-12 years old. Participants were categorized into the age groups of 6-7, 8-9, and 10-12, after which comparisons were performed between each age group for ASL analysis of cerebral blood flow (CBF). In total, the ADHD group exhibited significantly lower CBF in the left superior temporal gyrus and right middle frontal gyrus regions than the control group. Further analysis revealed: (1) The comparison between the ADHD group (N = 70) aged 6-7 and the age-matched control group (N = 33) showed no statistically significant difference between. (2) However, compared with the control group aged 8-9 (N = 39), the ADHD group of the same age (N = 53) showed significantly lower CBF in the left postcentral gyrus and left middle frontal gyrus regions. (3) Further, the ADHD group aged 10-12 (N = 34) demonstrated significantly lower CBF in the left superior occipital region than the age-matched control group (N = 37). These age-specific differences suggest variations in ADHD-related domains during brain development post age 6-7.

Cross-cultural differences in prefrontal cortex activity in moral judgment: A functional near-infrared spectroscopy (fNIRS) study based on the CNI model

BACKGROUND

In the past, comparative cultural neurological studies of moral judgments have mainly focused on Eastern and Western groups. We initially examined Japanese and Chinese groups, both East Asian cultures. We utilized a recently proposed polynomial model known as the "consequences, norms, and generalized inaction" (CNI) model to investigate the variations in the overall prefrontal cortex activity between these two groups during moral judgment.

METHODS

We employed functional near-infrared spectroscopy (fNIRS) to analyze the prefrontal cortex (PFC) activity within a CNI model of moral judgment among 23 healthy Japanese and 26 healthy Chinese adults.

RESULTS AND CONCLUSIONS

Our study revealed significant differences in the PFC activation between Japanese and Chinese individuals in the CNI moral judgment task context. Specifically, during the CNI task, Chinese men exhibited higher right dorsolateral prefrontal cortex (R-DLPFC) activity than Chinese women. In contrast, Japanese women showed greater left dorsolateral prefrontal cortex (L-DLPFC) activity than Japanese men. In an international comparison, R-DLPFC activity was higher in Chinese men than in Japanese men. Conversely, the left ventrolateral prefrontal cortex activity was higher in Japanese men compared to Chinese men. Additionally, among women, the right ventromedial prefrontal cortex activity was higher in Japanese women than in Chinese women. In conclusion, our findings support the perspective of cultural psychology and identify cultural and sex differences in PFC activity between Japanese and Chinese individuals.

The "psychiatric" neuron: the psychic neuron of the cerebral cortex, revisited

Nearly 25 years ago, Dr. Patricia Goldman-Rakic published her review paper, "The 'Psychic' Neuron of the Cerebral Cortex," outlining the circuit-level dynamics, neurotransmitter systems, and behavioral correlates of pyramidal neurons in the cerebral cortex, particularly as they relate to working memory. In the decades since the release of this paper, the existing literature and our understanding of the pyramidal neuron have increased tremendously, and research is still underway to better characterize the role of the pyramidal neuron in both healthy and psychiatric disease states. In this review, we revisit Dr. Goldman-Rakic's characterization of the pyramidal neuron, focusing on the pyramidal neurons of the prefrontal cortex (PFC) and their role in working memory. Specifically, we examine the role of PFC pyramidal neurons in the intersection of working memory and social function and describe how deficits in working memory may actually underlie the pathophysiology of social dysfunction in psychiatric disease states. We briefly describe the cortico-cortical and corticothalamic connections between the PFC and non-PFC brain regions, as well the microcircuit dynamics of the pyramidal neuron and interneurons, and the role of both these macro- and microcircuits in the maintenance of the excitatory/inhibitory balance of the cerebral cortex for working memory function. Finally, we discuss the consequences to working memory when pyramidal neurons and their circuits are dysfunctional, emphasizing the resulting social deficits in psychiatric disease states with known working memory dysfunction.

Cortical gray-white matter contrast abnormalities in male children with attention deficit hyperactivity disorder

Purpose

Presently, research concerning alterations in brain structure among individuals with attention deficit hyperactivity disorder (ADHD) predominantly focuses on entire brain volume and cortical thickness. In this study, we extend our examination to the cortical microstructure of male children with ADHD. To achieve this, we employ the gray-white matter tissue contrast (GWC) metric, allowing for an assessment of modifications in gray matter density and white matter microstructure. Furthermore, we explore the potential connection between GWC and the severity of disorder in male children by ADHD.

Methods

We acquired 3DT1 sequences from the public ADHD-200 database. In this study, we conducted a comparative analysis between 43 male children diagnosed with ADHD and 50 age-matched male controls exhibiting typical development trajectories. Our investigation entailed assessing differences in GWC and cortical thickness. Additionally, we explored the potential correlation between GWC and the severity of ADHD. To delineate the cerebral landscape, each hemisphere was subdivided into 34 cortical regions using freesurfer 7.2.0. For quantification, GWC was computed by evaluating the intensity contrast of non-normalized T1 images above and below the gray-white matter interface.

Results

Our findings unveiled elevated GWC within the bilateral lingual, bilateral insular, left transverse temporal, right parahippocampal and right pericalcarine regions in male children with ADHD when contrasted with their healthy counterparts. Moreover, the cortical thickness in the ADHD group no notable distinctions that of control group in all areas. Intriguingly, the GWC of left transverse temporal demonstrated a negative correlation with the extent of inattention experienced by male children with ADHD.

Conclusion

Utilizing GWC as a metric facilitates a more comprehensive assessment of microstructural brain changes in children with ADHD. The fluctuations in GWC observed in specific brain regions might serve as a neural biomarker, illuminating structural modifications in male children grappling with ADHD. This perspective enriches our comprehension of white matter microstructure and cortical density in these children. Notably, the inverse correlation between the GWC of the left transverse temporal and inattention severity underscores the potential role of structural and functional anomalies within this region in ADHD progression. Enhancing our insight into ADHD-related brain changes holds significant promise in deciphering potential neuropathological mechanisms.

The use of functional near-infrared spectroscopy in tracking neurodevelopmental trajectories in infants and children with or without developmental disorders: a systematic review

Understanding the neurodevelopmental trajectories of infants and children is essential for the early identification of neurodevelopmental disorders, elucidating the neural mechanisms underlying the disorders, and predicting developmental outcomes. Functional Near-Infrared Spectroscopy (fNIRS) is an infant-friendly neuroimaging tool that enables the monitoring of cerebral hemodynamic responses from the neonatal period. Due to its advantages, fNIRS is a promising tool for studying neurodevelopmental trajectories. Although many researchers have used fNIRS to study neural development in infants/children and have reported important findings, there is a lack of synthesized evidence for using fNIRS to track neurodevelopmental trajectories in infants and children. The current systematic review summarized 84 original fNIRS studies and showed a general trend of age-related increase in network integration and segregation, interhemispheric connectivity, leftward asymmetry, and differences in phase oscillation during resting-state. Moreover, typically developing infants and children showed a developmental trend of more localized and differentiated activation when processing visual, auditory, and tactile information, suggesting more mature and specialized sensory networks. Later in life, children switched from recruiting bilateral auditory to a left-lateralized language circuit when processing social auditory and language information and showed increased prefrontal activation during executive functioning tasks. The developmental trajectories are different in children with developmental disorders, with infants at risk for autism spectrum disorder showing initial overconnectivity followed by underconnectivity during resting-state; and children with attention-deficit/hyperactivity disorders showing lower prefrontal cortex activation during executive functioning tasks compared to their typically developing peers throughout childhood. The current systematic review supports the use of fNIRS in tracking the neurodevelopmental trajectories in children. More longitudinal studies are needed to validate the neurodevelopmental trajectories and explore the use of these neurobiomarkers for the early identification of developmental disorders and in tracking the effects of interventions.

Identification of the Neural Correlates Underlying Conflict Resolution Performance Using a Rodent Analogue of the Stroop Tests

The Stroop test is a widely used neuropsychological test measuring attention and conflict resolution, which shows sensitivity across a range of diseases, including Alzheimer's, Parkinson's and Huntington's diseases. A rodent analogue of the Stroop test, the Response-Conflict task (rRCT), allows for systematic investigation of the neural systems underpinning performance in this test. Little is known about the involvement of the basal ganglia in this neural process. The aim of this study was to use the rRCT to determine whether striatal subregions are recruited during conflict resolution processing. To achieve this, rats were exposed to Congruent or Incongruent stimuli in the rRCT and the expression patterns of the immediate early gene Zif268 were analysed throughout cortical, hippocampal and basal ganglia subregions. The results confirmed the previously reported involvement of prefrontal cortical and hippocampal regions, as well as identifying a specific role for the dysgranular (but not granular) retrosplenial cortex in conflict resolution. Finally, performance accuracy correlated significantly with reduced neural activation in the dorsomedial striatum. Involvement of the basal ganglia in this neural process has not previously been reported. These data demonstrate that the cognitive process of conflict resolution requires not only prefrontal cortical regions, but also recruits the dysgranular retrosplenial cortex and the medial region of the neostriatum. These data have implications for understanding the neuroanatomical changes that underpin impaired Stroop performance in people with neurological disorders.

Lack of functional brain connectivity was associated with poor inhibition in children with attention-deficit/hyperactivity disorder using near-infrared spectroscopy

Objectives

The present study aimed to evaluate the characteristics of functional brain connectivity in the resting state in children with attention deficit hyperactivity disorder (ADHD) and to assess the association between the connectivity and inhibition function using near-infrared spectroscopy (NIRS).

Methods

In total, 34 children aged 6-13 diagnosed with ADHD were recruited from Hangzhou Seventh People's Hospital. In comparison, 37 healthy children were recruited from a local primary school as controls matched by age and sex. We used NIRS to collect information on brain images. The Stroop test assessed inhibition function. We compared the differences in functional brain connectivity in two groups by analyzing the resting-state brain network. Pearson partial correlation analysis was applied to evaluate the correlation between functional brain connectivity and inhibition in all the children.

Results

Compared with the control group, results of NIRS images analysis showed that children with ADHD had significantly low functional brain connectivity in regions of the orbitofrontal cortex, left dorsolateral prefrontal cortex, left pre-motor and supplementary motor cortex, inferior prefrontal gyrus, and right middle temporal gyrus (p = 0.006). Inhibition function of children with ADHD was negatively correlated with functional brain connectivity (p = 0.009), while such correlation was not found in the control group.

Conclusion

The present study demonstrated that children with ADHD had relatively low connectivity in several brain regions measured at the resting state. Our results supported the evidence that lack of functional brain connectivity was associated with impaired inhibition function in children with ADHD.

Rethinking Theta/Beta Ratio in ADHD through Functional Data Analysis

ADHD is a neurodevelopmental disorder largely diffused among children and adolescents. The current method of diagnosis is based on agreed clinical literature such as DSM-5, by identifying and evaluating signs of hyperactivity and inattention. Multiple reviews have assessed that EEG is not sufficiently reliable for the diagnosis of ADHD. Theta-Beta Ratio is now the sole EEG parameter considered for analysis, although it is not robust enough to be utilized as a confirmatory technique for diagnosis. In this setting, new objective approaches for reliably classifying neurotypical and ADHD subjects are required. As a result, we suggest a new methodology based on Functional Data Analysis, a statistical class of methods for dealing with curves and functions. The initial stage in our method is to separate frequency bands from the EEG signal using a wavelet decomposition. We next compute the Power Spectral Densities of each of these bands and represent them as mathematical functions via spline interpolation. Finally, the relevance of the collected features is assessed using the Permutation ANOVA test. Using this method, we can detect different patterns in the PSDs of the groups and identify statistically significant features, confirming prior findings in the literature. We validate the features using classification techniques such as Bagging trees, Random Forest, and AdaBoost. The latter reaches the highest accuracy score of 76.65%, confirming the relevance of the extracted features.

Functional near-infrared spectroscopy in pediatric clinical research: Different pathophysiologies and promising clinical applications

Over its 30 years of existence, functional near-infrared spectroscopy (fNIRS) has matured into a highly versatile tool to study brain function in infants and young children. Its advantages, amongst others, include its ease of application and portability, the option to combine it with electrophysiology, and its relatively good tolerance to movement. As shown by the impressive body of fNIRS literature in the field of cognitive developmental neuroscience, the method's strengths become even more relevant for (very) young individuals who suffer from neurological, behavioral, and/or cognitive impairment. Although a number of studies have been conducted with a clinical perspective, fNIRS cannot yet be considered as a truly clinical tool. The first step has been taken in this direction by studies exploring options in populations with well-defined clinical profiles. To foster further progress, here, we review several of these clinical approaches to identify the challenges and perspectives of fNIRS in the field of developmental disorders. We first outline the contributions of fNIRS in selected areas of pediatric clinical research: epilepsy, communicative and language disorders, and attention-deficit/hyperactivity disorder. We provide a scoping review as a framework to allow the highlighting of specific and general challenges of using fNIRS in pediatric research. We also discuss potential solutions and perspectives on the broader use of fNIRS in the clinical setting. This may be of use to future research, targeting clinical applications of fNIRS in children and adolescents.

MYT1L is required for suppressing earlier neuronal development programs in the adult mouse brain

In vitro studies indicate the neurodevelopmental disorder gene myelin transcription factor 1-like (MYT1L) suppresses non-neuronal lineage genes during fibroblast-to-neuron direct differentiation. However, MYT1L's molecular and cellular functions in the adult mammalian brain have not been fully characterized. Here, we found that MYT1L loss leads to up-regulated deep layer (DL) gene expression, corresponding to an increased ratio of DL/UL neurons in the adult mouse cortex. To define potential mechanisms, we conducted Cleavage Under Targets & Release Using Nuclease (CUT&RUN) to map MYT1L binding targets and epigenetic changes following MYT1L loss in mouse developing cortex and adult prefrontal cortex (PFC). We found MYT1L mainly binds to open chromatin, but with different transcription factor co-occupancies between promoters and enhancers. Likewise, multiomic data set integration revealed that, at promoters, MYT1L loss does not change chromatin accessibility but increases H3K4me3 and H3K27ac, activating both a subset of earlier neuronal development genes as well as Bcl11b, a key regulator for DL neuron development. Meanwhile, we discovered that MYT1L normally represses the activity of neurogenic enhancers associated with neuronal migration and neuronal projection development by closing chromatin structures and promoting removal of active histone marks. Further, we showed that MYT1L interacts with HDAC2 and transcriptional repressor SIN3B in vivo, providing potential mechanisms underlying repressive effects on histone acetylation and gene expression. Overall, our findings provide a comprehensive map of MYT1L binding in vivo and mechanistic insights into how MYT1L loss leads to aberrant activation of earlier neuronal development programs in the adult mouse brain.

Can biomarkers be used to diagnose attention deficit hyperactivity disorder?

Currently, the diagnosis of attention deficit hyperactivity disorder (ADHD) is solely based on behavioral tests prescribed by the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5). However, biomarkers can be more objective and accurate for diagnosis and evaluating treatment efficacy. Thus, this review aimed to identify potential biomarkers for ADHD. Search terms “ADHD,” and “biomarker” combined with one of “protein,” “blood/serum,” “gene,” and “neuro” were used to identify human and animal studies in PubMed, Ovid Medline, and Web of Science. Only papers in English were included. Potential biomarkers were categorized into radiographic, molecular, physiologic, or histologic markers. The radiographic analysis can identify specific activity changes in several brain regions in individuals with ADHD. Several molecular biomarkers in peripheral blood cells and some physiologic biomarkers were found in a small number of participants. There were no published histologic biomarkers for ADHD. Overall, most associations between ADHD and potential biomarkers were properly controlled. In conclusion, a series of biomarkers in the literature are promising as objective parameters to more accurately diagnose ADHD, especially in those with comorbidities that prevent the use of DSM-5. However, more research is needed to confirm the reliability of the biomarkers in larger cohort studies.

Modulation effect of non-invasive transcranial ultrasound stimulation in an ADHD rat model

Objective.Previous studies have demonstrated that transcranial ultrasound stimulation (TUS) with noninvasive high penetration and high spatial resolution has an effective neuromodulatory effect on neurological diseases. Attention deficit hyperactivity disorder (ADHD) is a persistent neurodevelopmental disorder that severely affects child health. However, the neuromodulatory effects of TUS on ADHD have not been reported to date. This study aimed to investigate the neuromodulatory effects of TUS on ADHD.Approach.TUS was performed in ADHD model rats for two consecutive weeks, and the behavioral improvement of ADHD, neural activity of ADHD from neurons and neural oscillation levels, and the plasma membrane dopamine transporter and brain-derived neurotrophic factor (BDNF) in the brains of ADHD rats were evaluated.Main results.TUS can improve cognitive behavior in ADHD rats, and TUS altered neuronal firing patterns and modulated the relative power and sample entropy of local field potentials in the ADHD rats. In addition, TUS can also enhance BDNF expression in the brain tissues.Significance. TUS has an effective neuromodulatory effect on ADHD and thus has the potential to clinically improve cognitive dysfunction in ADHD.

Response inhibition in children with different subtypes/presentations of attention deficit hyperactivity disorder: A near-infrared spectroscopy study

Background

Executive dysfunction in children with attention deficit hyperactivity disorder (ADHD) is thought to be closely related to the prefrontal cortex (PFC). However, there is controversy over the activation of the PFC in children with ADHD. Differences could be related to the subtype. Meanwhile, no study to date has used functional near-infrared spectroscopy (fNIRS) to explore the differences between subtypes. Thus, this study aimed to explore the activation of the PFC in children with different subtypes of ADHD during executive function task.

Methods

Participants in this study include typically developing (TD) children (n = 28), ADHD-predominantly inattentive (ADHD-PI) (n = 39) and ADHD-combined (ADHD-C) (n = 24). To examine the executive function of ADHD, the Go/No-go task is chosen to assess the response inhibition function. The activation of PFC in all participants during the Go/No-go task was recorded by fNIRS. Meanwhile, behavioral data were also recorded.

Results

Both TD and ADHD children activated the right PFC [middle frontal gyrus (MFG) and inferior frontal gyrus (IFG)] during response inhibition. However, the range and degree of activation differed among these groups. Compared with TD children, those with ADHD-PI had a smaller extent of activation in the right PFC, and those with ADHD-C only had a tendency to enhance activation. In addition, children with ADHD-PI and ADHD-C had impaired activation of the temporal gyrus. Besides, compared with ADHD-C and TD, those with ADHD-PI also had impaired activation of the right precentral gyrus (PG), and the supplementary motor area (SMA). Compared with ADHD-PI, ADHD-C showed decreased activation of the right MFG. The activation of Ch34 (BA44, rPFC) in children with ADHD-PI and ADHD-C was negatively correlated with their clinical symptoms.

Conclusion

The activation of the PFC in children with different subtypes of ADHD has both commonalities and differences. The degree of activation of the right PFC Ch34 in children with ADHD is negatively correlated with clinical symptoms. fNIRS could be served as a candidate hemodynamic biomarker for the diagnosis of ADHD.

YOGA FOR EMOTIONAL CONTROL IN CHILDREN WITH ADHD

ABSTRACT Introduction: Attention deficit hyperactivity disorder (ADHD) is one of the most common childhood disorders, with several negative social and behavioral consequences. Yoga shows appropriate efficacy in different conditions but is poorly explored during childhood. Objective: Analyze the efficacy of yoga in regulating emotions and symptoms in children with ADHD. Methods: This experimental study followed up on a control group of 30 children with ADHD. They were randomly allocated group into control (N=15) and experimental (N=15) through the block randomization method. Participants completed the emotion regulation and Conner scale (CBRS) before, after, and 60 days after yoga exercise (20 sessions twice a week). Results: After 8 weeks of training, participants’ emotion regulation and ADHD symptoms improved significantly. The improvement in emotion regulation and ADHD symptoms was maintained at follow-up. Conclusion: Yoga training proved to be an easy and inexpensive method to improve the mental and physical condition of children with ADHD. Level of evidence II; Therapeutic studies - investigating treatment outcomes.

Front and center: Maturational dysregulation of frontal lobe functional neuroanatomic connections in attention deficit hyperactivity disorder

Frontal lobe function may not universally explain all forms of attention deficit hyperactivity disorder (ADHD) but the frontal lobe hypothesis described supports an internally consistent model for integrating the numerous behaviors associated with ADHD. The paper examines the developmental trajectories of frontal and prefrontal lobe development, framing ADHD as maturational dysregulation concluding that the cognitive, motor, and behavioral abilities of the presumptive majority of ADHD children may not primarily be disordered or dysfunctional but reflect maturational dysregulation that is inconsistent with the psychomotor and cognitive expectations for the child’s chronological and mental age. ADHD children demonstrate decreased activation of the right and middle prefrontal cortex. Prefrontal and frontal lobe regions have an exuberant network of shared pathways with the diencephalic region, also having a regulatory function in arousal as well as with the ascending reticular formation which has a capacity for response suppression to task-irrelevant stimuli. Prefrontal lesions oftentimes are associated with the regulatory breakdown of goal-directed activity and impulsivity. In conclusion, a presumptive majority of childhood ADHD may result from maturational dysregulation of the frontal lobes with effects on the direct, indirect and/or, hyperdirect pathways.

Functional near-infrared spectroscopy in developmental psychiatry: a review of attention deficit hyperactivity disorder

Research has linked executive function (EF) deficits to many of the behavioral symptoms of attention deficit hyperactivity disorder (ADHD). Evidence of the involvement of EF impairment in ADHD is corroborated by accumulating neuroimaging studies, specifically functional magnetic resonance imaging (fMRI) studies. However, in recent years, functional near-infrared spectroscopy (fNIRS) has become increasingly popular in ADHD research due to its portability, high ecological validity, resistance to motion artifacts, and cost-effectiveness. While numerous studies throughout the past decade have used fNIRS to examine alterations in neural correlates of EF in ADHD, a qualitative review of the reliability of these findings compared with those reported using gold-standard fMRI measurements does not yet exist. The current review aims to fill this gap in the literature by comparing the results generated from a qualitative review of fNIRS studies (children and adolescents ages 6-16 years old) to a meta-analysis of comparable fMRI studies and examining the extent to which the results of these studies align in the context of EF impairment in ADHD. The qualitative analysis of fNIRS studies of ADHD shows a consistent hypoactivity in the right prefrontal cortex in multiple EF tasks. The meta-analysis of fMRI data corroborates altered activity in this region and surrounding areas during EF tasks in ADHD compared with typically developing controls. These findings indicate that fNIRS is a promising functional brain imaging technology for examining alterations in cortical activity in ADHD. We also address the disadvantages of fNIRS, including limited spatial resolution compared with fMRI.

Electrophysiological correlates of the reverse Stroop effect: Results from a simulated handgun task

The color-word reverse Stroop (RS) effect still represents an interesting puzzle for cognitive researchers as an interference between incongruent ink colors and the meaning of the words is not always found. Here, we examined whether an unfamiliar and complex visuomotor task would produce a RS effect. Forty inexperienced shooters carried out a simulated shooting task. To test if the RS effect is related to the stimuli processing or to a late processing of the color (early and late time-windows), electroencephalographic global field power (GFP) variations were recorded with a high-impedance system (32 channels configuration in a standard monopolar montage, referenced to FCz and grounded to FPz). The color-word RS effect was reflected in the performance of 32 participants, suggesting that the strength of the association between the target and the specific response requested might be central to the RS interference. This behavioral result was paralleled by GFP modulations in 20 participants. A significant increase of the GFP for the congruent trials (e.g., the word "red" written in red ink) was recorded after stimulus presentation (conflict detection), followed by an increase for the incongruent trials (e.g., the word "red" written in green ink) just before the shooting (conflict resolution). Despite the limitations of the study, such as the inclusion of a low number of channels in the GFP analyses, the results suggest that the RS interference is easily elicited in tasks requiring an unfamiliar response, which supports the strength of association hypothesis. Moreover, as implied by the GFP modulations, the interference might occur early in time, but also in a later stage, closer to the response.

The amplitude of fNIRS hemodynamic response in the visual cortex unmasks autistic traits in typically developing children

Autistic traits represent a continuum dimension across the population, with autism spectrum disorder (ASD) being the extreme end of the distribution. Accumulating evidence shows that neuroanatomical and neurofunctional profiles described in relatives of ASD individuals reflect an intermediate neurobiological pattern between the clinical population and healthy controls. This suggests that quantitative measures detecting autistic traits in the general population represent potential candidates for the development of biomarkers identifying early pathophysiological processes associated with ASD. Functional near-infrared spectroscopy (fNIRS) has been extensively employed to investigate neural development and function. In contrast, the potential of fNIRS to define reliable biomarkers of brain activity has been barely explored. Features of non-invasiveness, portability, ease of administration, and low-operating costs make fNIRS a suitable instrument to assess brain function for differential diagnosis, follow-up, analysis of treatment outcomes, and personalized medicine in several neurological conditions. Here, we introduce a novel standardized procedure with high entertaining value to measure hemodynamic responses (HDR) in the occipital cortex of adult subjects and children. We found that the variability of evoked HDR correlates with the autistic traits of children, assessed by the Autism-Spectrum Quotient. Interestingly, HDR amplitude was especially linked to social and communication features, representing the core symptoms of ASD. These findings establish a quick and easy strategy for measuring visually-evoked cortical activity with fNIRS that optimize the compliance of young subjects, setting the background for testing the diagnostic value of fNIRS visual measurements in the ASD clinical population.

Effect of Distractors on Sustained Attention and Hyperactivity in Youth With Attention Deficit Hyperactivity Disorder Using a Mobile Virtual Reality School Program

OBJECTIVE

This study examined whether distractors in virtual reality (VR) environment affected the attention and hyperactivity in children and adolescents with ADHD.

METHOD

A total of 40 students (21 ADHD, 19 controls) aged between 9 and 17 years participated in this study. A rapid visual information processing task utilizing VR (VR-RVP) was performed under two conditions (no-distractor and distractor condition). Task performance and head movement during each condition were compared, and additional analyses were conducted after grouping participants into two developmental stages.

RESULTS

Children with ADHD performed comparably to the controls under the distractor condition, but had poorer performance under the no-distractor condition. They displayed more head movement under the distractor condition than in the no-distractor condition.

CONCLUSION

VR is possibly a useful tool for investigating the effect of distractors on individuals with ADHD, and children with ADHD are more vulnerable to a low-level stimulation situation than normal children in VR.

Brain activity in the prefrontal cortex during cancelation tasks: Effects of the stimulus array

Cancelation tasks have been widely used to neurologically assess selective attention and visual search in various clinical and research settings. However, there is still a lack of evidence regarding the effect of differences in array conditions on brain activity in the prefrontal cortex (PFC) and its association with developmental characteristics. This study employed cancelation tasks to investigate the effects of varying array conditions on oxygenated hemoglobin (oxy-Hb) concentrations. Data from 24 healthy adults were analyzed based on performance during two-block-design type of cancelation tasks with different array conditions (i.e., structured array vs. random array). Performance was assessed based on the number of correct responses, incorrect responses, hit ratios, and performance scores (PS); while PFC activity was examined using near-infrared spectroscopy. In addition, characteristics of attention-deficit/hyperactivity disorder (ADHD) were assessed using the ADHD-Rating Scale-IV (ADHD-RS-IV). Results revealed that the numbers of correct responses and PS were higher in the random array, but there was no difference in the incorrect responses and hit ratio. Similarly, we observed that the oxy-Hb concentration in the PFC significantly increased during the task. Additionally, in the structured array, a significant relationship between task performance and characteristics of ADHD was found but not in the random array. Our results regarding the above-mentioned changes in oxy-Hb concentration suggest that the PFC region is involved in selective attention. We also found that cancelation tasks in a structured array may be useful in evaluating the characteristics of ADHD.

Detection of ADHD From EEG Signals Using Different Entropy Measures and ANN

Attention deficit hyperactivity disorder (ADHD) is a prevalent behavioral, cognitive, neurodevelopmental pediatric disorder. Clinical evaluations, symptom surveys, and neuropsychological assessments are some of the ADHD assessment methods, which are time-consuming processes and have a certain degree of uncertainty. This research investigates an efficient computer-aided technological solution for detecting ADHD from the acquired electroencephalography (EEG) signals based on different nonlinear entropy estimators and an artificial neural network classifier. Features extracted through fuzzy entropy, log energy entropy, permutation entropy, SURE entropy, and Shannon entropy are analyzed for effective discrimination of ADHD subjects from the control group. The experimented results confirm that the proposed techniques can effectively detect and classify ADHD subjects. The permutation entropy gives the highest classification accuracy of 99.82%, sensitivity of 98.21%, and specificity of 98.82%. Also, the potency of different entropy estimators derived from the t-test reflects that the Shannon entropy has a higher P-value (>.001); therefore, it has a limited scope than other entropy estimators for ADHD diagnosis. Furthermore, the considerable variance found from potential features obtained in the frontal polar (FP) and frontal (F) lobes using different entropy estimators under the eyes-closed condition shows that the signals received in these lobes will have more significance in distinguishing ADHD from normal subjects.

A MYT1L syndrome mouse model recapitulates patient phenotypes and reveals altered brain development due to disrupted neuronal maturation

Human genetics have defined a new neurodevelopmental syndrome caused by loss-of-function mutations in MYT1L, a transcription factor known for enabling fibroblast-to-neuron conversions. However, how MYT1L mutation causes intellectual disability, autism, ADHD, obesity, and brain anomalies is unknown. Here, we developed a Myt1l haploinsufficient mouse model that develops obesity, white-matter thinning, and microcephaly, mimicking common clinical phenotypes. During brain development we discovered disrupted gene expression, mediated in part by loss of Myt1l gene-target activation, and identified precocious neuronal differentiation as the mechanism for microcephaly. In contrast, in adults we discovered that mutation results in failure of transcriptional and chromatin maturation, echoed in disruptions in baseline physiological properties of neurons. Myt1l haploinsufficiency also results in behavioral anomalies, including hyperactivity, muscle weakness, and social alterations, with more severe phenotypes in males. Overall, our findings provide insight into the mechanistic underpinnings of this disorder and enable future preclinical studies.

Brain activity in the prefrontal cortex during a cancellation task: effects of the target-to-distractor ratio

Cancellation tasks have been widely used to neurologically assess selective attention and visual search in various clinical and research settings. However, there is still a lack of evidence regarding the effect of the level of task difficulty on brain activity in the prefrontal cortex (PFC). This study implemented cancellation tasks to investigate the effects of varying task difficulty on oxygenated hemoglobin (oxy-Hb) concentrations. Data from 21 healthy adults were analyzed based on performance during three-block-design types of cancellation tasks with different T/D ratios (i.e., 1/9, 2/8, and 3/7). Performance was assessed via the number of correct responses, incorrect responses, hit ratios, achievement ratios, and performance scores (PS), while PFC activity was examined using near-infrared spectroscopy. Both the numbers of correct responses and PS were the lowest for the smallest T/D ratio. Similarly, we observed that the oxy-Hb concentration in the PFC was significantly increased during the task. Our results support the findings of previous studies that used conventional cancellation tasks, thus suggesting that block design types are suitable for examinations in the same contexts. Regarding the above-mentioned changes in the oxy-Hb concentration, the findings suggest that the PFC region is involved in selective attention.

Clinical Applications of Functional Near-Infrared Spectroscopy in Children and Adolescents with Psychiatric Disorders

The purpose of this review is to examine the clinical use of functional near-infrared spectroscopy (fNIRS) in children and adolescents with psychiatric disorders. Many studies have been conducted using objective evaluation tools for psychiatric evaluation, such as predicting psychiatric symptoms and treatment responses. Compared to other tools, fNIRS has the advantage of being a noninvasive, inexpensive, and portable method and can be used with patients in the awake state. This study mainly focused on its use in patients with attention-deficit/hyperactivity disorder and autism spectrum disorder. We hope that research involving fNIRS will be actively conducted in various diseases in the future.

The acute effect of moderate-intensity exercise on inhibitory control and activation of prefrontal cortex in younger and older adults

Exercise has a significant effect on maintaining the health of inhibitory function, a fundamental cognitive ability that supports daily mental processes. While previous studies have shown that a single bout of exercise, called acute exercise, could improve inhibitory control by stimulating the prefrontal cortex (PFC) and the arousal state, few studies have focused on the differences in the effects of exercise by age. In this study, young and older adults (mean age, 22.7 ± 1.4 and 68.7 ± 5.3 years, respectively) engaged in acute moderate-intensity exercise and inhibitory control. Before and at 5 and 30 min after exercise, the participants were asked to complete the reverse Stroop task, and their arousal state and PFC activity were measured using functional near-infrared spectroscopy. The findings showed that the overall inhibitory control improved immediately after performing acute exercise and remained improved even after 30 min. Particularly, there was a difference in the arousal state and middle PFC activity between the two age groups. Especially, the young adults showed an increase in the arousal state post-exercise, while the older adults tended to show an increase in the middle PFC activity. These results suggested that the acute exercise effects on the arousal state and PFC activity may vary depending on the developmental stage, but not for inhibitory control overtime. When these findings are considered, it is important to note that the exercise impact on cognitive control remained the same throughout the generations despite the observed changes in its impact on internal states.

Intentional Discontinuation of Psychostimulants Used to Treat ADHD in Youth: A Review and Analysis

Objectives: This paper reviews the literature on intentional discontinuation of psychostimulants in ADHD to summarize what is known about clinical course of controlled discontinuation and guide practitioners who are considering stopping these medications for youth with ADHD. Methods: A systematic search was executed in Cochrane CENTRAL, EMBASE, Psychinfo, and MEDLINE databases to identify all articles that addressed the topic of deprescribing of psychotropic medications in children and adolescents. Keywords and search strings were developed using "PICO" framework, involving Population of interest (<18 y.o.), Intervention ("discontinuation," "deprescribing," and synonyms), Comparator (continuation of specific medications), and Outcomes. Ten reviewers conducted the initial screen via a single reviewer system. Articles that met a set of three inclusionary criteria were selected for full text review and identification as specific to discontinuation of stimulants in ADHD. Results: The literature review identified 35 articles specifically addressing intentional deprescribing, discontinuation, tapering, or withdrawal of stimulants for children and adolescents with ADHD. In addition to providing broad support for the efficacy of stimulants to treat ADHD and reduce negative outcomes, there is a distinct population of children and adolescents with ADHD who do not relapse or deteriorate when taken off medications for ADHD. The majority of articles addressed either the re-emergence of ADHD symptoms or side effects, both desired and adverse, following discontinuation of stimulants. While confirming the ability of stimulants to treat ADHD in youth, our results support periodic consideration of trials of stopping medications to determine continued need. Conclusions: This systematic review summarizes the literature on deprescribing stimulants for ADHD in children and adolescents. Further research is needed to determine the optimal duration of treatment, identify patients that may benefit from medication discontinuation, and inform evidence-based guidelines for discontinuation when appropriate. More research is needed to understand and define the subgroup of youth who may succeed with stimulant discontinuation.

Detection of Executive Performance Profiles Using the ENFEN Battery in Children Diagnosed With Attention-Deficit Hyperactivity Disorder

Attention-deficit hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorders in children and adolescents. People who have this disorder are characterized by presenting difficulties in the processes of sustained attention, being very active, and having poor control of their impulses. Despite the high prevalence of this disorder and the existence of various tests used for its diagnosis, few data are available regarding the usefulness and diagnostic validity of these tools. Given the difficulties that these subjects present in executive functions, the aim of this study was to evaluate whether the Neuropsychological Assessment of Executive Functions battery for Children (ENFEN, for its acronym in Spanish, Portellano et al., 2009) allows to establish specific profiles of executive performance for people with attention-deficit hyperactivity disorder (ADHD). The sample was made up of 197 participants of both sexes, aged between 6 and 12 years age (134 with a clinical diagnosis and 63 without pathology). A nonexperimental design was followed, using a comparative descriptive study method. The results indicated that the scales of phonological fluency, color path, rings, and interference are the most associated with the diagnosis of ADHD, providing data on inhibition, mental flexibility, sustained and selective attention, planning, verbal fluency, and working memory, among others. The practical implication of these results is in line with providing support in the clinical diagnosis that is carried out in children's mental health units. In addition, the ENFEN tool can be valued as a suitable psychometric instrument in the psychoeducational field, helping professionals in a school environment to be more aware of the areas of cognitive development in which a student diagnosed with ADHD will have more difficulties and, in doing so, providing more adjusted and effective psychopedagogical measures when it comes to supporting students in their adaptation to the school environment.

Executive dysfunction in medication-naïve children with ADHD: A multi-modal fNIRS and EEG study

OBJECTIVE

Children with attention deficit hyperactivity disorder (ADHD) exhibit deficits in executive function. Since there are no clear biomarkers for the disorder, this study aimed to investigate the neurophysiological biomarkers for deficits in executive function in children with ADHD using functional near-infrared spectroscopy (fNIRS) and electroencephalography.

METHODS

Twenty patients diagnosed with ADHD and 19 typically developing children (TDC; 8-11 years old) were included. Event related potentials (ERPs) were recorded using an electroencephalogram (EEG) and oxygenated hemoglobin concentrations (Oxy-Hb) were recorded using fNIRS during a colored Go/NoGo task, simultaneously. Latencies and amplitudes of NoGo-N2 and NoGo/Go-P3 tasks were measured using EEG.

RESULTS

Children with ADHD showed significantly decreased Oxy-Hb in the right frontal cortex as well as longer NoGo-P3 latencies and a decreased NoGo/Go-P3 amplitude. There was a significant positive correlation between the Oxy-Hb and NoGo/Go-P3 amplitude.

CONCLUSIONS

These results suggest that children with ADHD experience executive dysfunction. Hemodynamic and electrophysiological findings during the Go/NoGo task might be useful as a biomarker of executive function.

SIGNIFICANCE

These findings have key implications for understanding the pathophysiology of deficits in executive function in ADHD.

Neural Responses to Reward in a Gambling Task: Sex Differences and Individual Variation in Reward-Driven Impulsivity

Previous work suggests sex differences in reward sensitivity. However, it remains unclear how men and women differ in the neural processes of reward-driven impulsivity. With a data set of 968 subjects (502 women) curated from the Human Connectome Project, we investigated sex differences in regional activations to reward and to punishment in a gambling task. Individual variations in reward-driven impulsivity were quantified by the difference in reaction time between reward and punishment blocks in the gambling task, as well as by a behavioral measure of delay discounting. At a corrected threshold, men and women exhibited significant differences in regional activations to reward and to punishment. Longer reaction times during reward versus punishment blocks, indicative of more cautious responding, were associated with left-hemispheric lateral prefrontal cortical activation to reward in men but not women. Steeper discounting was associated with higher activation to reward in the right-hemispheric dorsal anterior cingulate cortex and angular gyrus in women but not men. These sex differences were confirmed in slope tests. Together, the results highlight the sex-specific neural processes of reward-driven impulsivity with left-hemispheric prefrontal cortex supporting impulse control in men and right-hemispheric saliency circuit playing a more important role in diminished impulse control in women.