Typically Developing Children Group Research Articles

Altered Intrinsic Brain Spontaneous Activities in Children With Autism Spectrum Disorder Comorbid ADHD

Objective: The study involved 17 children with Autism Spectrum Disorder (ASD), 21 with ADHD, 30 with both (ASD + ADHD), and 28 typically developing children (TD). Methods: The amplitude of low-frequency fluctuations (ALFF) was measured as a regional brain function index. Intrinsic functional connectivity (iFC) was also analyzed using the region of interest (ROI) identified in ALFF analysis. Statistical analysis was done via one-way ANCOVA, Gaussian random field (GRF) theory, and post-hoc pair-wise comparisons. Results: The ASD + ADHD group showed increased ALFF in the left middle frontal gyrus (MFG.L) compared to the TD group. In terms of global brain function, the ASD group displayed underconnectivity in specific regions compared to the ASD + ADHD and TD groups. Conclusion: The findings contribute to understanding the neural mechanisms underlying ASD + ADHD.

The role of vocabulary and grammar in the listening text comprehension of school-age Cantonese-speaking children with developmental language disorder

The current study examined the role of vocabulary and grammar in the listening comprehension of school-age Cantonese-speaking children with developmental language disorder in Hong Kong. Participants were 692 typically developing children (TD) and 53 children with developmental language disorder (DLD) and they were tested with a standardized test of oral Cantonese, which includes measures on listening comprehension, receptive and expressive grammar, expressive vocabulary, word definition and lexical relations. The results from multiple regression analysis revealed that listening comprehension of the TD group was explained by receptive grammar, expressive vocabulary, and lexical relationships. However, children of the DLD group mainly relied on a subset of their vocabulary knowledge, as measured in a lexical relation task on antonym, in understanding the text under the constraint of a limited grammatical knowledge.

Motor-cognitive coupling is impaired in children with mild or severe forms of developmental coordination disorder

Children with developmental coordination disorder (DCD) show deficits in motor-cognitive coupling. However, it remains unclear whether such deficits depend on the severity of DCD. The aim of this study was to examine cognitive-motor coupling under different levels of inhibitory control in children with severe (s-DCD) or moderate DCD (m-DCD), compared with typically-developing children (TDC). The performance of 29 primary-school children aged 6–12 years with s-DCD (Mage = 9.12 ± 1.56 years), 53 m-DCD (Mage = 8.78 ± 1.67 years), and 201 TDC (Mage = 9.20 ± 1.50 years) was compared on a double jump reaching task (DJRT) paradigm, presented on a large 42-inch touchscreen. The task display had a circular home-base, centred at the bottom of the display, and three target locations at radials of −20°, 0°, and 20°, 40 cm above the home-base circle. For the standard double-jump reaching task (DJRT), children moved their index finger from home-base circle to touch the target stimulus as fast as possible; 20% were jump trials where the target shifted left or right at lift-off. For the anti-jump reaching task (AJRT), 20% of trials required an anti-jump movement, touching the contralateral target location. While no group differences were shown on the DJRT, the DCD group were slower to complete reaching movements than the TDC group on AJRT; on the latter, the two DCD sub-groups were not shown to differ. Results confirm the presence of motor inhibition deficits in DCD which may not be dependent on the motor severity of the disorder.

Working Memory-Related Neurofunctional Correlates Associated with the Frontal Lobe in Children with Familial vs. Non-Familial Attention Deficit/Hyperactivity Disorder.

Attention deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder with high prevalence, heritability, and heterogeneity. Children with a positive family history of ADHD have a heightened risk of ADHD emergence, persistence, and executive function deficits, with the neural mechanisms having been under investigated. The objective of this study was to investigate working memory-related functional brain activation patterns in children with ADHD (with vs. without positive family histories (ADHD-F vs. ADHD-NF)) and matched typically developing children (TDC). Voxel-based and region of interest analyses were conducted on two-back task-based fMRI data of 362 subjects, including 186, 96, and 80 children in groups of TDC, ADHD-NF, and ADHD-F, respectively. Relative to TDC, both ADHD groups had significantly reduced activation in the left inferior frontal gyrus (IFG). And the ADHD-F group demonstrated a significant positive association of left IFG activation with task reaction time, a negative association of the right IFG with ADHD symptomatology, and a negative association of the IFG activation laterality index with the inattention symptom score. These results suggest that working memory-related functional alterations in bilateral IFGs may play distinct roles in ADHD-F, with the functional underdevelopment of the left IFG significantly informing the onset of ADHD symptoms. Our findings have the potential to assist in tailored diagnoses and targeted interventions in children with ADHD-F.

The development of speech output processing skills in Greek-speaking children

ABSTRACT There is a growing body of literature on phonological development in Greek-speaking children, either typically developing (TD) or with speech sound disorders (SSD). In this paper, a cross-sectional longitudinal approach was used to investigate the development of speech output processing skills in TD Greek-speaking preschool-aged children. Moreover, a group of Greek-speaking children with SSD were assessed to identify potential loci of impairment in atypical development. The developmental study involved two groups: group 1 (n = 16) aged 3;0–3;5 years and group 2 (n = 22) aged 4;6–5;0 years, assessed at three assessment points six months apart. Children with SSD (n = 15) aged 5;6–6;0 years were assessed to be compared with performance of group 2 TD children (at the third assessment point). Assessment tasks included (a) a picture naming task, (b) a task of real word repetition and (c) a task of nonword repetition. A strong time effect was found in both groups of TD children in the development of speech output processing abilities. Performance accuracy was higher on tasks including real words than nonwords; children performed more accurately on repetition rather than spontaneous naming of real words; repetition accuracy on 2–3 syllables items was significantly better than on 4–5 syllables items. Children with SSD were outperformed by TD children of the same age in all assessment tasks; lexicality and word length effect were found in the clinical group. Findings from the present study may be used as a starting point to diagnose children with speech production difficulties in Greece.

Correlation Analysis between Eye Movement Patterns and Reading Comprehension Skills by Reading Condition in Children with Typical Development and Language Impairment

Objectives: The purpose of this study was to identify whether there was a significant difference in reading comprehension in typically developing children (TD) and children with language impairment (LI) in early school age according to reading conditions, and to determine whether there was a significant correlation between reading comprehension skills and eye movement patterns in each group.Methods: A total of 213 children (TD: 183; LI: 30) in the 1st and 2nd grades of elementary school participated in this study. According to the reading conditions (reading while listening, reading only), all children were randomly assigned to perform text reading tasks, and real-time data collection was carried out through an attached eye-tracker.Results: There was no significant difference in story understanding according to reading conditions between groups, but it was confirmed that the correlation patterns between each group’s reading comprehension and eye movement patterns were different depending on reading conditions.Conclusion: In the TD group this study found that the faster the processing speed, the higher the reading processing efficiency. On the other hand, in the LI group, the processing speed was generally slow due to their poor literacy or cognitive processing speed, therefore there was no correlation between eye movement patterns and reading comprehension skills.

Time to rest a hypothesis? Accumulating evidence that periodic leg movements during sleep are not increased in children with attention deficit hyperactivity disorder (ADHD): results of a case-control study and a meta-analysis.

To address the hypothesis that periodic leg movements during sleep (PLMS) are more frequent in children with attention deficit hyperactivity disorder (ADHD) when compared to typically developing (TD) children. To that end we both analyzed PLMS in a recent case-control study and conducted a systematic review and meta-analysis of PLMS frequency in children with ADHD and TD children. In our case-control study we compared PLMS frequency of 24 children with ADHD (mean age 11 years, 17 male) to that of 22 age matched typically developing (TD) children (mean age 10 years, 12 male). A subsequent meta-analysis included 33 studies that described PLMS frequency in groups of children with ADHD and/or groups of TD children. The case-control study did not show any differences in the frequency of PLMS between children with ADHD and TD children, a result that was consistent across a range of different definitions of PLMS, which in turn had a significant and systematic effect on PLMS frequency. The meta-analysis compared the average PLMS indices and the proportion of children with elevated PLMS indices between children with ADHD and TD children and across a number of analyses did not find any meta-analytic results that supported the hypothesis that PLMS are more frequent in children with ADHD. Our results suggest that PLMS are not more frequent in children with ADHD compared to TD children. A finding of frequent PLMS in a child with ADHD should therefore be considered a separate disorder and prompt specific diagnostic and therapeutic strategies.

Robotic Ankle Training Improves Sensorimotor Functions in Children with Cerebral Palsy—A Pilot Study

Children with cerebral palsy (CP) have sensorimotor impairments including weakness, spasticity, reduced motor control and sensory deficits. Proprioceptive dysfunction compounds the decreased motor control and mobility. The aims of this paper were to (1) examine proprioceptive deficit of lower extremities of children with CP; (2) study improvement in proprioception and clinical impairments through robotic ankle training (RAT). Eight children with CP participated in a 6-week RAT with pre and post ankle proprioception, clinical, biomechanical assessment compared to the assessment of eight typically developing children (TDC). The children with CP participated in passive stretching (20 min/session) and active movement training (20 to 30 min/session) using an ankle rehabilitation robot (3 sessions/week over 6 weeks, total of 18 sessions). Proprioceptive acuity measured as the plantar and dorsi-flexion motion at which the children recognized the movement was 3.60 ± 2.28° in dorsiflexion and -3.72 ± 2.38° in plantar flexion for the CP group, inferior to that of the TDC group's 0.94 ± 0.43° in dorsiflexion (p = 0.027) and -0.86 ± 0.48° in plantar flexion (p = 0.012). After training, ankle motor and sensory functions were improved in children with CP, with the dorsiflexion strength increased from 3.61 ± 3.75 Nm to 7.48 ± 2.75 Nm (p = 0.018) and plantar flexion strength increased from -11.89 ± 7.04 Nm to -17.61 ± 6.81 Nm after training (p = 0.043). The dorsiflexion AROM increased from 5.58 ± 13.18° to 15.97 ± 11.21° (p = 0.028). The proprioceptive acuity showed a trend of decline to 3.08 ± 2.07° in dorsiflexion and to -2.59 ± 1.94° in plantar flexion (p > 0.05). The RAT is a promising intervention for children with CP to improve sensorimotor functions of the lower extremities. It provided an interactive and motivating training to engage children with CP in rehabilitation to improve clinical and sensorimotor performance.

Brain network study of attentional cognitive impairment in children with bronchial asthma.

Bronchial asthma often causes cognitive impairment, especially attentional deficit, which has a serious impact on children's learning. This study aims to provide objective indicators for the evaluation of attention in asthma children. Thirty-one asthmatic and typically developing children (TDC) were tested by resting-state functional magnetic resonance imaging (rs-fMRI). Brain network-based methods of degree centricity and voxel-mirrored homotopic connectivity (VMHC) methods were used in the study. Compared with the TDC group, asthmatic children had lower DC values in the right superior frontal gyrus (after FDR correction, P < 0.05). Meanwhile, VMHC values of bilateral superior frontal gyrus and bilateral superior parietal lobule in asthmatic children were lower than those in TDC group (after FDR correction, P < 0.05). There was significant correlation between the correct percentage of CPT and DC value in right superior frontal gyrus, VMHC value in right superior frontal gyrus, and right superior parietal lobule. In this study, impaired superior frontal gyrus and parietal lobe function are associated with attentional deficit in asthmatic children, and these brain regions are key brain regions in attention-related networks.

Behaviors related to autism spectrum disorder in children with developmental language disorder and children with 22q11.2 deletion syndrome.

Children with Developmental Language Disorder (DLD) are at an increased risk to develop behaviors associated with Autism Spectrum Disorder (ASD). The relationship between early language difficulties and the occurrence of ASD-related behaviors in DLD is poorly understood. One factor that may hinder progress in understanding this relationship is the etiological heterogeneity of DLD. We therefore study this relationship in an etiologically homogeneous group of children, who share phenotypic characteristics with children with DLD: children with the 22q11.2 Deletion Syndrome (22q11DS). We compare children with 22q11DS, to children with DLD and age-matched typically developing children (TD). 44 children with 22q11DS, 65 children with DLD and 81 TD children, between 3.0-6.5 years old, participated in a longitudinal cohort study that included a baseline measure and a follow-up measure with a 1-year interval. A parental questionnaire (SRS-2) was used to measure the incidence of behaviors in two key behavioral domains associated with ASD: Social Communication and Interaction and Restricted Repetitive Behaviors and Interests. At baseline, we assessed children's expressive and receptive language abilities as well as their intellectual functioning with standardized tests. We compared the distribution of ASD-related behaviors between the three groups. We used regression analyses to investigate whether language abilities at baseline predict ASD-related behavior at follow-up, accounting for ASD-related behavior at baseline, demographic variables and intellectual functioning. Both the children with 22q11DS and the children with DLD displayed significantly more ASD-related behaviors than the TD children. Over 30% of children in both clinical groups had scores exceeding the subclinical threshold for ASD in both behavioral domains. Both in 22q11DS and DLD, baseline receptive language scores were negatively correlated with ASD-related behaviors 1 year later, when controlling for baseline SRS-scores. However, this association was statistically significant only in children with 22q11DS, even when controlled for IQ-scores, and it was significantly stronger as than in the TD group. The strength of the association did not differ significantly between 22q11DS and DLD. Both children with 22q11DS and children with DLD present with elevated rates of ASD-related behaviors at a preschool-age. Only in children with 22q11DS we observed that weaker receptive language skills were related to increased behavioral problems in the domain of social communication and interaction one year later. Our findings indicate that relations between early language impairment and other behavioral phenotypes may be more feasible to detect in a subgroup of children with a homogeneous etiology, than in a group of children with a heterogeneous etiology (such as children with DLD). Our results in 22q11DS reveal that receptive language is especially important in predicting the occurrence of ASD-related behaviors. Future research is needed to determine to what extent receptive language predicts the occurrence of ASD-related behaviors in children with DLD, especially among those children with DLD with the weakest receptive language. Clinically, screening for ASD-related behaviors in children with developmental language difficulties is recommended from a young age, especially among children with receptive language difficulties.

RJAfinder: An automated tool for quantification of responding to joint attention behaviors in autism spectrum disorder using eye tracking data.

Deficits in responding to joint attention (RJA) are early symptoms of autism spectrum disorder (ASD). Currently, no automated tools exist for identifying and quantifying RJA behaviors. A few eye tracking studies have investigated RJA in ASD children but have produced conflicting results. In addition, little is known about the trajectory of RJA development through developmental age. Here, a new video was designed including 12 clips of an actor pointing to or looking at an object. Eye tracking technology was used to monitor RJA in three groups: 143 ASD children assessed with the Autism Diagnostic Interview-Revised (ADI-R) and the Autism Diagnostic Observation Schedule (ADOS) (4-7 years old), 113 age- and gender-matched typically developing children (TDC), and 43 typically developing adults (TDA) (19-32 years old). RJAfinder was developed in R and MATLAB to quantify RJA events from the eye tracking data. RJA events were compared among the three groups. Spearman correlation coefficients between total number of RJA events in ASD and the Social Responsiveness Scale (SRS) scores were calculated. A logistic regression model was built using the average valid sampling rate and the total number of RJA events as two predictive variables to classify ASD and TDC groups. ASD children displayed statistically significantly less RJA events than the TDC and TDA groups with medium-to-large-sized effects. ASD and TDC children both displayed more RJA events in response to pointing stimuli than to looking stimuli. Our logistic regression model predicted ASD tendency with 0.76 accuracy in the testing set. RJA ability improved more slowly between the ages of 4-7 years old in the ASD group than in the TDC group. In ASD children, RJA ability showed negative correlation with SRS total T-score as well as the scores of five subdomains. Our study provides an automated tool for quantifying RJA and insights for the study of RJA in ASD children, which may help improve ASD screening, subtyping, and behavior interventions.

Perception of the /t/-/k/ contrast by Mandarin-speaking children with Speech Sound Disorders

ABSTRACT Mandarin-speaking children with speech sound disorders (SSD) often show difficulties in producing alveolar and velar plosives contrasts (e.g., /t/ vs. /k/). But it remains unclear whether such phonological disorder correlates with the perception of the contrast between alveolar and velar plosives. The present study assessed whether Mandarin-speaking children with SSD who substituted [t] for /k/ in production could perceptually distinguish between /t/ and /k/, and compared their results with those from typically developing children (TDC) and typically adults (TA). We adopted a categorical perception paradigm with a /ta/-/ka/ continuum. The continuum included nine stimuli, which were synthesized from a naturally-produced /ta/. The SSD, TDC, and TA groups completed both identification and discrimination tasks that required perceptual judgment of individual stimulus and pairs of stimuli from the continuum. The results showed that the TDC and TA groups showed typical patterns of categorical perception in the continuum. But the SSD group only reached or was slightly above the chance level in the identification task and did not show significant difference among pairs of stimuli in the discrimination task. Their performance was significantly different from that of the TDC and TA groups and lacked typical patterns of categorical perception. The results suggested that their perception of /t/ vs. /k/ may be impaired. Considering the SSD group’s speech errors, this perception defect may be a cause for their tendency of substituting [t] for /k/ in production.

Altered neural flexibility in children with attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorders of childhood, and is often characterized by altered executive functioning. Executive function has been found to be supported by flexibility in dynamic brain reconfiguration. Thus, we applied multilayer community detection to resting-state fMRI data in 180 children with ADHD and 180 typically developing children (TDC) to identify alterations in dynamic brain reconfiguration in children with ADHD. We specifically evaluated MR derived neural flexibility, which is thought to underlie cognitive flexibility, or the ability to selectively switch between mental processes. Significantly decreased neural flexibility was observed in the ADHD group at both the whole brain (raw p = 0.0005) and sub-network levels (p < 0.05, FDR corrected), particularly for the default mode network, attention-related networks, executive function-related networks, and primary networks. Furthermore, the subjects with ADHD who received medication exhibited significantly increased neural flexibility (p = 0.025, FDR corrected) when compared to subjects with ADHD who were medication naïve, and their neural flexibility was not statistically different from the TDC group (p = 0.74, FDR corrected). Finally, regional neural flexibility was capable of differentiating ADHD from TDC (Accuracy: 77% for tenfold cross-validation, 74.46% for independent test) and of predicting ADHD severity using clinical measures of symptom severity (R2: 0.2794 for tenfold cross-validation, 0.156 for independent test). In conclusion, the present study found that neural flexibility is altered in children with ADHD and demonstrated the potential clinical utility of neural flexibility to identify children with ADHD, as well as to monitor treatment responses and disease severity.

Restricted and Repetitive Behaviors and Interests in Young Children with Autism: A Comparative Study.

To examine the frequency of repetitive behaviors among children with autism spectrum disorder (ASD) and compare it to age-matched developmentally delayed (DD) and typically developing children (TD). Twenty-five children (3-8 y) with a diagnosis of ASD were compared to two age-matched control groups namely the DD and TD groups. The Repetitive Behaviors Scale-Revised (RBS-R) was administered to the parents to assess the frequency, severity, and impairment associated with restricted, repetitive behaviors, and interests (RRBIs) displayed. The study was cleared by the institute ethics committee. The three groups were well matched on age and sex distribution and comparisons on the RBS-R showed that the ASD group had a significantly higher total score (F = 51.52, p = 0.0001) and number of items endorsed on the scale (F = 37.91, p = 0.0001). Stepwise multiple regression analysis revealed that 35.8% of the variance in the total RRBI score of the ASD children was explained by the age and severity of autism (F = 6.12. p = .008). Older children with severe ASD features had significantly higher total RRBI scores. RRBIs are not just specific to autism and should not be used in isolation to identify children with autism. Gaining a complete understanding of the complexity and variability of the restricted interests would help in improving the diagnostic procedures and in the development of a comprehensive therapeutic plan.

Decision-making and Risky Behavior in Individuals with Attention-Deficit/Hyperactivity Disorder: A 10-year Longitudinal Study

ABSTRACT We assessed 85 children with Attention-Deficit/Hyperactivity Disorder (ADHD) and 50 typically developing children (TD) (Mage = 11.59, 57.8% boys) with the Hungry Donkey Task (HDT) at baseline and 2-year follow-up, and the Iowa Gambling Task at 10-year follow-up (75% retention). Improvement in the proportion of advantageous choices was observed from two- to 10-year follow-up, but the ADHD group improved less and was outperformed by the TD group at the 10-year follow-up. More advantageous choices on the HDT at baseline predicted less risky behavior at 10-year follow-up. Male sex and more inattentive or externalizing symptoms at baseline predicted more risky behavior.

Do comorbid symptoms discriminate between autism spectrum disorder, ADHD and nonverbal learning disability?

Characterizing the functioning of individuals with neurodevelopmental disorders is crucial to their diagnosis. Research has found that children with different neurodevelopmental disorders, including autism spectrum disorders (ASD), attention deficit and hyperactivity disorder (ADHD), and nonverbal learning disability (NLD), may have comorbid symptoms of anxiety and depression, and problems with pragmatic language. The main aim of the present study was to identify any differences in the above-mentioned comorbid symptoms associated with these clinical profiles. A second aim was to establish how well signs of pragmatic language difficulties could discriminate between the three clinical profiles, in terms of their diagnostic power. For this purpose, 107 participants from 8 to 16 years old with a diagnosis of ASD, ADHD or NLD were compared with a group of typically-developing children. Self-reports on symptoms of anxiety and depression, and parents’ reports on social and communication problems were analyzed. Our findings confirmed that symptoms of anxiety and depression, and problems with pragmatic language are associated with different neurodevelopmental disorders, but not in the same way. In terms of diagnostic power, we found that pragmatic language difficulties clearly discriminated children with ASD, ADHD or NLD from typically-developing children. Importantly, pragmatic language difficulties also discriminated adequately between ASD and NLD. Our findings are discussed in terms of the value of considering comorbid symptoms to obtain a more accurate diagnosis of neurodevelopmental disorders.

Discrepancies between mother and father ratings of child behavior after early mild traumatic brain injury

ABSTRACT Mild traumatic brain injuries (mTBI) are highly prevalent during early childhood and can lead to behavioral difficulties. Parent report questionnaires are widely used to assess children’s behavior, but they are subject to parental bias. The aim of this study was to investigate parental discrepancies in internalized and externalized behavior ratings of children who sustain mTBI in early childhood (i.e., between 18 and 60 months) and to determine if parenting stress or family burden related to the injury contribute to parental discrepancies. Mothers and fathers of 85 children with mTBI, 58 orthopedic injured (OI), and 82 typically developing children (TDC) completed the Child Behavior Checklist 6 months after the injury. The primary caregiver completed the Parental Distress subscale of the Parenting Stress Index and the Family Burden of Injury Interview. Mothers reported more internalized and externalized behavior problems than fathers in the mTBI group. No group difference was found in the OI or TDC groups. Neither parenting stress nor family burden related to the injury predicted discrepancies in behavior ratings. Mothers’ and fathers’ perceptions of behavior after their young child sustains mTBI appear to differ, suggesting that both parents’ views are useful in understanding outcome. This difference was not found in either of the comparison groups indicating that factors related to mTBI may underlie the rating discrepancies.

Analysis of the relationship between muscular strength and joint stiffness in children with Down syndrome during drop landing.

BACKGROUND: Children with Down syndrome (DS) have critical biomechanical impairments such as increased ligamentous laxity, muscle hypotonia, and dysfunctional motor coordination, which makes performing everyday tasks challenging.OBJECTIVE: The purpose of the study was to explore the differences in the vertical joint stiffness, plantar force, and range of motion during drop landing for DS and age-matched typically developing children.METHODS: Six young male children with DS and age-matched seven healthy typically developing children (TD) assessed joint strength using an isokinetic dynamometer and performed five trials of single-leg drop jump using force platform and motion capture system.RESULTS: The peak vertical ground reaction force (VGRF), Range of motion (ROM), joint stiffness, and joint strength of lower limb were calculated and compared across DS and TD groups. The results revealed a significantly larger peak VGRF [2.857, 0.001] values for the DS group compared to the TD groups. The results of Spearman’s correlation analysis showed a negative correlation between hip joint stiffness and knee joint ROM [0.886, 0.05] and ankle joint stiffness and knee joint ROM [0.829, 0.05] for DS.CONCLUSIONS: The abnormal movements observed among DS was not due to the difference in stiffness of the lower extremity but due to the utilization of different landing mechanisms with changes in ROM.

Counter-movement jump characteristics in children with Charcot–Marie–Tooth type 1a disease

BackgroundPoor performance in sports, especially activities that require explosive movements, is a common reason for initial presentation of children with Charcot–Marie–Tooth type 1a (CMT1a) to the paediatric neuromuscular specialist. Research questionThe aim of this descriptive, retrospective study was to analyse counter-movement jump characteristics in children with CMT1a in comparison to those in typically developing children (TDC). MethodsThis retrospective study included seven patients with CMT1a and 44 TDC from our data pool. All the participants performed counter-movement jumps, and jump height, peak force, time to peak force, average and peak rate of force development and net vertical impulse were then calculated. For statistical comparison by means of an independent Student’s t-test, children with CMT1a were compared to seven sex- and age-matched TDC. Correlation coefficients were calculated to determine the relationship between the force-time variables and jump height. ResultsPeak force, net vertical impulse and jump height values in the CMT1a group were significantly lower than those in the TDC group. There were no between-group differences in the time to peak force or average and peak rate of force development. In terms of task symmetry, the correlation between the time-force curve of the left and right leg in the CMT1a group was reduced as compared with that in the TDC group. In both groups, among the parameters measured, there was a significant correlation between jump height and net vertical impulse. SignificanceThis study showed that reduced jump performance in children with CMT1a, as demonstrated by decreased counter-movement jump height, was due to a reduced net impulse during this explosive movement task. This finding is critical for children with CMT1a and has to be considered in clinical management and activities of daily living (e.g. sports lessons in school).

Urine Organic Acids as Metabolic Indicators for Global Developmental Delay/Intellectual Disability in Chinese Children.

Objective: The purpose of this study was to search for differential metabolites in urine organic acids, and to characterize metabolic features that can be used to identify metabolites for exploration of global developmental delay (GDD)/intellectual disability (ID) etiology and pathogenesis. Methods: We screened positive test results that could explain GDD/ID from 1,253 cases, and the major differential metabolites in 132 urine organic acids from the 1,230 cases with negative results (863 GDD cases, 367 ID cases), and 100 typically developing children (TD). Non-supervisory principal component analysis and orthogonal partial least squares discriminant analysis were used to develop models to distinguish GDD/ID from TD children, and to detect major differential metabolites. Results: We get 23 positive results that could identify the cause of GDD/ID from 1253 cases diagnosed with GDD/ID. Among 1,230 negative results, we get the differential metabolites of the GDD group and the ID group had the same trend compared with the TD group. Twenty four differential metabolites were obtained from the GDD group, and 25 from the ID group (VIP > 1.0, p < 0.01). These differential metabolites were mainly related to the following pathways: the synthesis and degradation of ketone bodies, citrate cycle, alanine, aspartate and glutamate metabolism, pyrimidine metabolism, butanoate metabolism, pyruvate metabolism, fatty acid biosynthesis, valine, leucine and isoleucine degradation. Conclusion: The use of metabolomics research methods to detect urine organic acids of children with GDD/ID can discover differential metabolites, which might be valuable for future research on the etiology, pathogenesis, prognosis and possible interventions of GDD/ID. The significantly altered differential metabolites indicators could therefore be potential diagnostic biomarkers for GDD/ID.