Cognitive and neuroimaging findings in developmental coordination disorder: new insights from a systematic review of recent research

Auditory rhythm facilitates perception and action in children at risk for developmental coordination disorder

Developmental Coordination Disorder (DCD) is a common neurodevelopmental disorder featuring deficits in motor coordination and motor timing among children. Deficits in rhythmic tracking, including perceptually tracking and synchronizing action with auditory rhythms, have been studied in a wide range of motor disorders, providing a foundation for developing rehabilitation programs incorporating auditory rhythms. We tested whether DCD also features these auditory-motor deficits among 7-10 year-old children. In a speech recognition task with no overt motor component, modulating the speech rhythm interfered more with the performance of children at risk for DCD than typically developing (TD) children. A set of auditory-motor tapping tasks further showed that, although children at risk for DCD performed worse than TD children in general, the presence of an auditory rhythmic cue (isochronous metronome or music) facilitated the temporal consistency of tapping. Finally, accuracy in the recognition of rhythmically modulated speech and tapping consistency correlated with performance on the standardized motor assessment. Together, the results show auditory rhythmic regularity benefits auditory perception and auditory-motor coordination in children at risk for DCD. This provides a foundation for future clinical studies to develop evidence-based interventions involving auditory-motor rhythmic coordination for children with DCD.

Children with developmental coordination disorders: a review of approaches to assessment and intervention

Developmental Coordination Disorder (DCD) is a neurodevelopmental disorder characterized by deficits in motor skills, with gross and fine motor dysfunction being the main symptom. This condition greatly impairs children's daily life, learning, and social interaction. Symptoms typically appear during preschool or school age, and if left untreated, they can persist into adulthood. Thus, early assessment and intervention are crucial to improve the prognosis. This study aims to review the existing literature on DCD, providing a comprehensive overview of the assessment for children with DCD in terms of body functions and structures, activities and participation, and environmental factors within the framework of the International Classification of Functioning, Disability, and Health - Children and Youth (ICF-CY). Additionally, specific rehabilitation interventions will be described, offering valuable insights for the clinical assessment and intervention of children with DCD.

Evaluating the influence of feedback on motor skill learning and motor performance for children with developmental coordination disorder: a systematic review

Introduction

Children with developmental coordination disorder (DCD) have difficulties with learning and performing physical tasks. It is well known that task-specific practice is effective in improving motor skills. Additional feedback during practice may function as a quality improvement mechanism and therefore enhance motor skill outcomes.

Aims

To investigate the effect of different forms of feedback on motor learning and motor performance in children with DCD.

Methods

A systematic review was conducted (registration CRD42020175118) to investigate the effectiveness of different types of feedback, compared to other forms of feedback, or no additional feedback, on motor learning and motor performance outcomes in children with DCD. The search was run across six electronic databases (last search January 2024). Two reviewers independently screened studies for inclusion, assessed the quality of included studies, and extracted relevant data. A narrative synthesis was performed and included studies that assessed motor learning and/or performance outcomes following an intervention that delivered a specific form of feedback in comparison to another form of feedback or no specific feedback.

Results

14 articles from 13 trials were included in this review. Feedback was delivered by providing various forms of feedback, including: knowledge of results, focus of attention and augmented feedback delivered via technology. No significant differences were found between different forms of feedback for motor learning or performance outcomes for children with DCD. Interventions that used technology (with augmented feedback) to deliver the intervention were found to be as effective as traditional therapy. All groups who participated in therapy, regardless of the presence or type of feedback received, improved in overall scores on a motor performance outcome assessment.

Conclusion

Despite the clear rationale for using feedback-oriented interventions for children with DCD, there is surprisingly limited and low-quality research. There is no clear evidence that one form of feedback is more effective than another, although it appears that feedback delivered via technology may be as effective as feedback delivered in traditional therapy interventions for children with DCD. Further exploration is required from appropriately powered and well-designed trials.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=175118, identifier (CRD42020175118).

Developmental coordination disorder in preterm children: A systematic review and meta-analysis

This study aimed to review the prevalence of developmental coordination disorder (DCD) in individuals born preterm and systematically explore this prevalence according to gestational age and different assessment cut-offs and compare it to full-term peers. The eligibility criteria were observational and experimental studies reporting the prevalence of DCD in preterm individuals. A systematic search was performed in databases from inception until March 2022. Two independent reviewers performed the selection. Study quality assessment was performed using the checklists from Joanna Briggs Institute (JBI). Data analysis was performed on Excel and Review Manager Software 5.4. Among the 1774 studies identified, 32 matched the eligibility criteria. The pooled estimate rate of the DCD rate in preterm was 21% (95% confidence interval [CI] 17.8-24.3). The estimate rates were higher as gestational age decreased, and preterm children are two times more likely to have DCD than their full-term peers risk ratio (RR) 2.2 (95% CI 1.77-2.79). The limitation was high heterogeneity between studies; the assessment tools, cut-off points and age at assessment were diverse. This study provided evidence that preterm children are at higher risk for DCD than full-term children, and the risks increased as gestational age decreased.

Effects of a highly intensive balance therapy camp in children with developmental coordination disorder - An intervention protocol

BACKGROUND

Children with Developmental Coordination Disorder (DCD) often (<87 %) experience postural control problems, impacting all levels of the International Classification of Functioning, Disability and Health (ICF) including their daily participation, self-esteem and mental health. Due to the multisystemic nature of postural control, comprehensive therapy should target all systems which is currently not the case. Highly intensive therapy is effective and commonly used in pediatric populations, but has not been explored yet to train postural control in children with DCD.

AIMS

To investigate the effects of a highly intensive functional balance therapy camp at all ICF levels in children with DCD.

METHODS AND PROCEDURES

The effects on postural control, muscle activity, brain alterations, self-perceived competence, self-identified goals, gross motor activities and participation are evaluated. Participants are assessed pre- and post-intervention, including a 3 months follow-up. Forty-eight children with DCD, aged 6-12 years old, receive 40 h of comprehensive balance training. This intervention is fun, individually tailored, targets all postural control systems, implements different motor learning strategies and includes both individual and group activities.

CONCLUSION

Novel insights into the effects of a highly intensive comprehensive balance therapy camp designed for children with DCD will be gained at all levels of the ICF.

Locomotor-cognitive dual-tasking in children with developmental coordination disorder

Introduction

Children with Developmental Coordination Disorder (DCD) demonstrate deficits in predictive motor control and aspects of cognitive control compared with their typically developing (TD) peers. Adjustment to dynamic environments depends on both aspects of control and the deficits for children with DCD may constrain their ability to perform daily actions that involve dual-tasking. Under the assumption that motor-cognitive integration is compromised in children with DCD, we examined proportional dual-task costs using a novel locomotor-cognitive dual-task paradigm that enlisted augmented reality. We expect proportional dual-task performance costs to be greater for children with DCD compared to their TD peers.

Methods

Participants were 34 children aged 6-12 years (16 TD, 18 DCD) who walked along a straight 12 m path under single- and dual-task conditions, the cognitive task being visual discrimination under simple or complex stimulus conditions presented via augmented reality. Dual-task performance was measured in two ways: first, proportional dual-task costs (pDTC) were computed for cognitive and gait outcomes and, second, within-trial costs (p-WTC) were measured as the difference on gait outcomes between pre- and post-stimulus presentation.

Results

On measures of pDTC, TD children increased their double-limb support time when walking in response to a dual-task, while the children with DCD increased their locomotor velocity. On p-WTC, both groups increased their gait variability (step length and step width) when walking in response to a dual-task, of which the TD group had a larger proportional change than the DCD group. Greater pDTCs on motor rather than cognitive outcomes were consistent across groups and method of dual-task performance measurement.

Discussion

Contrary to predictions, our results failed to support dramatic differences in locomotor-cognitive dual-task performance between children with DCD and TD, with both groups tending to priorities the cognitive over the motor task. Inclusion of a within-trial calculation of dual-task interference revealed an expectancy effect for both groups in relation to an impending visual stimulus. It is recommended that dual-task paradigms in the future continue to use augmented reality to present the cognitive task and consider motor tasks of sufficient complexity to probe the limits of performance in children with DCD.

Far Transfer Effects of Trainings on Executive Functions in Neurodevelopmental Disorders: A Systematic Review and Metanalysis

Executive Functions are a set of interrelated, top-down processes essential for adaptive goal-directed behaviour, frequently impaired across different neurodevelopmental disorders with variable degrees of severity. Many executive-function-training studies in children with neurodevelopmental disorders have focused on near effects, investigating post-treatment improvements on directly trained processes, while enhancements of skills not directly trained, defined as far effects, are less considered, albeit these could be extremely relevant for reducing the negative impact of a disorder's core symptomatology. This systematic review and metanalysis aims to investigate the far effect outcomes after EF training in children with different types of neurodevelopmental disorders. 17 studies met the inclusion criteria for the systematic review, while 15 studies were selected in the metanalysis. An overall statistically significant effect size was found in the majority of far effect outcome measures considered in the studies. In particular, trainings on executive functions determine significant far effects on daily life functioning (0.46, 95% CI: [0.05-0.87]) and clinical symptoms (0.33, 95% CI: [0.15-0.51]). Despite a high variability of the results, intensity, frequency and the laboratory/life contexts dimension seem to be the most influential variables in determining far effects. This systematic review and metanalysis highlights the need to measure far effects of executive function training in neurodevelopmental disorders, selecting treatments not only on directly targeted processes, but also according to far impacts on the functional weakness of the disorder.

Anthropometric, physical activity, and psychological characteristics of Korean adults with and without developmental coordination disorder (DCD)

Developmental Coordination Disorder (DCD), also known as Dyspraxia, is characterized by movement difficulties in individuals without discernible neurological disorders or identifiable medical conditions. Previous studies from various countries have highlighted disparities in anthropometric, physical activity, and psychological characteristics between children diagnosed with DCD and their typically developing (TD) peers. These differences are influenced by sociocultural norms and geographical locations. However, little attention has been given to scrutinizing analogous differences in adult populations, particularly within Republic of Korea. This study aims to address this knowledge gap by employing a battery of questionnaires to assess anthropometric, physical activity, and psychological traits in a cohort of 377 Korean adults, encompassing those with DCD (n = 54) alongside TD counterparts (n = 323). It was hypothesized that Korean adults with DCD would exhibit higher body mass index and lower ratings in physical activity and psychological characteristics than TD, consistent with the previous studies performed in other countries on children. The results showed no statistically significant differences between the DCD and TD groups in anthropometric characteristics such as weight (kg), height (cm), and body mass index. The prevalence of walking and biking for daily commuting in daily routines within Korean society might have contributed to the mitigation of anthropometric among individuals with/without DCD. Statistically significant differences were found in physical activity levels at work and recreational settings, as shown in physical activity scores and duration. The DCD group also displayed lower scores across several psychological characteristics, including exercise adherence, intrinsic motivation, self-efficacy, physical self-concept, exercise expectations, and intrinsic regulation. These findings underscore the necessity of incorporating sociocultural dynamics when investigating anthropometric, physical activity, and psychological characteristics in adults with DCD. Their perceived difficulties in fine motor skills were also significantly poor than TD. Future research studies are warranted to elucidate the underlying mechanisms driving the observed patterns in this study, thus contributing to a more nuanced comprehension of how DCD manifests within specific sociocultural contexts.

Visuomotor adaptation, internal modelling, and compensatory movements in children with developmental coordination disorder

BACKGROUND

Developmental coordination disorder (DCD) is one of the most prevalent developmental disorders in school-aged children. The mechanisms and etiology underlying DCD remain somewhat unclear. Altered visuomotor adaptation and internal model deficits are discussed in the literature.

AIMS

The study aimed to investigate visuomotor adaptation and internal modelling to determine whether and to what extent visuomotor learning might be impaired in children with DCD compared to typically developing children (TD). Further, possible compensatory movements during visuomotor learning were explored.

METHODS AND PROCEDURES

Participants were 12 children with DCD (age 12.4 ± 1.8, four female) and 18 age-matched TD (12.3 ± 1.8, five female). Visuomotor learning was measured with the Motor task manager. Compensatory movements were parameterized by spatial and temporal variables.

OUTCOMES AND RESULTS

Despite no differences in visuomotor adaptation or internal modelling, significant main effects for group were found in parameters representing movement accuracy, motor speed, and movement variability between DCD and TD.

CONCLUSIONS AND IMPLICATIONS

Children with DCD showed comparable performances in visuomotor adaptation and internal modelling to TD. However, movement variability was increased, whereas movement accuracy and motor speed were reduced, suggesting decreased motor acuity in children with DCD.

Atypical procedural learning skills in children with Developmental Coordination Disorder

We investigated the procedural learning deficit hypothesis in Developmental Coordination Disorder (DCD) while controlling for global performance such as slower reaction times (RTs) and variability. Procedural (sequence) learning was assessed in 31 children with DCD and 31 age-matched typically developing (TD) children through a serial reaction time task (SRTT). Sequential and random trial conditions were intermixed within five training epochs. Two repeated measures ANOVAs were conducted on a Sequence-Specific Learning Index (SSLI) and a Global Performance Index (GPI, speed/accuracy measure) with Epoch (for SSLI and GPI) and Condition (for GPI) as within-subjects factors, and Group as between-subjects factor. Controlling for RTs differences through normalized RTs, revealed a global reduction of SSLI in children with DCD compared with TD peers suggesting reduced sequence learning skills in DCD. Still, a significant Group x Condition interaction observed on GPI indicated that children from both groups were able to discriminate between sequential and random trials. DCD presented reduced procedural learning skills after controlling for global performance. This finding highlights the importance of considering the general functioning of the child while assessing learning skills in patients.

Effects of the Specific Eye Fixation Training on Fine Visuomotor Coordination in Children with Attention Deficit Hyperactivity Disorder

This study investigated the effects of quiet eye training (QET) on the neuropsychological functioning and fine motor performance of children with attention deficits. The participant cohort consisted of 106 children with attention deficit hyperactivity disorder (ADHD) between the ages of 8 and 12 years. The children were assigned to either the QET group (n = 54) or the control group (n = 52). The QET group went through a 5-week intervention in which the performance of blocks of targeting tasks was preceded by watching split-screen video footage featuring the gaze and body movements of a skilled model performing a throwing motion. Both groups underwent pre-test and post-test assessments, which included the reaction test of alertness, go/no-go inhibition test, and motor performance series test. The QET group demonstrated significant improvements in attentional engagement, inhibitory control, and fine motor skills, which require precise and fast visuomotor coordination. These results highlight the potential benefits of QET intervention in ameliorating attention deficits and enhancing fine aiming motor skills in children with ADHD. However, task specificity was evident, indicating that the intervention effects were most pronounced for the hand fine motor aiming tasks requiring both precision and speed.

A systematic review of behavioral and neurobiological profiles associated with coexisting attention-deficit/hyperactivity disorder and developmental coordination disorder

Attention-deficit/hyperactivity disorder (ADHD) and developmental coordination disorder (DCD) co-occur in approximately 50% of cases. This study aimed to characterize the behavioral, cognitive, and neurobiological profiles of co-occurring ADHD and DCD diagnoses by mapping, synthesizing, and providing a critical appraisal of the existing literature. A systematic search was conducted across four databases (MEDLINE, PsycINFO, Embase, and Scopus) to identify studies comparing a coexisting ADHD+DCD diagnosis to ADHD and DCD alone. From 2353 screened articles, 15 behavioral and 10 neuroimaging studies were included. Collectively, these studies suggest that the comorbid ADHD+DCD presentation constitutes a more severe phenotype characterized by neurocognitive differences associated with both conditions. Despite sharing some common neural features, our findings support the separate etiology hypothesis indicating that neural network alterations in individuals with ADHD+DCD represent a unique neural pattern rather than a sum of ADHD and DCD characteristics. Considering the heterogeneity inherent to both ADHD and DCD, future studies should involve rigorous and comprehensive assessment procedures to delineate how different subtypes of each diagnosis relate to distinct performance characteristics.

Cultural Adaptation of the MABC-2 Checklist as a Screening Tool for Developmental Coordination Disorder in Schools

The purpose of this study was to adapt the MABC-2 Checklist to Czech primary schools by examining of its content validity and feasibility. The content validity achieved the satisfactory level in the second round of panels of experts on child motor development. The evidence on feasibility was obtained from classroom teachers who described this tool as clear, objective and having logical structure and its administration as comprehensible and fast. The MABC-2 Checklist is applicable instrument for the Czech school environment, but its adaptation to various countries should consider the items representing the common motor skills in local children.

Health-related quality of life in children with developmental coordination disorder: a systematic review

The aims of this study were (1) to synthesize evidence of the general health-related quality of life in children with DCD compared to their typically developing peers, and (2) to verify which domains of HRQOL are more compromised in children with DCD. A systematic search was carried out to identify cross-sectional studies that evaluated self-perception and/or the parent's perception of the HRQOL in children with and without DCD as an outcome. The methodological quality of the studies was assessed, and the effect size calculated. Initial searches in the databases identified 1092 articles. Of these, six were included. Most of the articles (5/6) included noted that children with DCD show a significantly lower HRQOL than their typically developing peers. Regarding the most compromised HRQOL domains, the results are heterogeneous. Most studies (3/6) had moderate methodological quality, and two studies were classified as high methodological quality. Effect sizes ranged from low to high.

"The clumsiness is always present": Parents perspectives of their adolescents with pDCD

AIM

This study elicited the perspectives of parents of adolescents with probable Developmental Coordination Disorder (pDCD) of the implications of DCD on their adolescents' daily-life and the parents' coping strategies and future concerns.

METHODS

Using a phenomenological approach and thematic analysis, we conducted a focus group including 7 parents of adolescents with pDCD aged 12-18 yrs.

FINDINGS

Three major themes emerged from the data: (a) Manifestation and implications of DCD; Parents described the performance challenges and strengths of their adolescents; (b) Discrepancy in perceptions of DCD: Parents described a gap between them and their children's, and between the parents themselves, in their views of the child's difficulties; (c) Diagnosis of DCD and strategies for overcoming its implications: Parents' expressed the pros and cons of labeling and described strategies they used to assist their children.

CONCLUSIONS

It appears that adolescents with pDCD continue to experience performance limitations in daily-life activities, and psychosocial difficulties. Yet, parents and their adolescents do not always view these limitations in a similar manner. Therefore, it is important that clinicians obtain information from both parents and their adolescents'. These results may assist in developing a client-centered intervention protocol for parents and adolescents.

Motor learning in developmental coordination disorder: behavioral and neuroimaging study

Developmental coordination disorder (DCD) is characterized by motor learning deficits that are poorly understood within whole-body activities context. Here we present results of one of the largest non-randomized interventional trials combining brain imaging and motion capture techniques to examine motor skill acquisition and its underpinning mechanisms in adolescents with and without DCD. A total of 86 adolescents with low fitness levels (including 48 with DCD) were trained on a novel stepping task for a duration of 7 weeks. Motor performance during the stepping task was assessed under single and dual-task conditions. Concurrent cortical activation in the prefrontal cortex (PFC) was measured using functional near-infrared spectroscopy (fNIRS). Additionally, structural and functional magnetic resonance imaging (MRI) was conducted during a similar stepping task at the beginning of the trial. The results indicate that adolescents with DCD performed similarly to their peers with lower levels of fitness in the novel stepping task and demonstrated the ability to learn and improve motor performance. Both groups showed significant improvements in both tasks and under single- and dual-task conditions at post-intervention and follow-up compared to baseline. While both groups initially made more errors in the Stroop task under dual-task conditions, at follow-up, a significant difference between single- and dual-task conditions was observed only in the DCD group. Notably, differences in prefrontal activation patterns between the groups emerged at different time points and task conditions. Adolescents with DCD exhibited distinct prefrontal activation responses during the learning and performance of a motor task, particularly when complexity was increased by concurrent cognitive tasks. Furthermore, a relationship was observed between MRI brain structure and function measures and initial performance in the novel stepping task. Overall, these findings suggest that strategies that address task and environmental complexities, while simultaneously enhancing brain activity through a range of tasks, offer opportunities to increase the participation of adolescents with low fitness in physical activity and sports.

Cognitive Orientation to Daily Occupational Performance: A Randomized Controlled Trial Examining Intervention Effects on Children with Developmental Coordination Disorder Traits

Children with traits of developmental coordination disorder (DCD-t) may experience occupational performance problems that go unrecognized and therefore may not be adequately supported. The cognitive orientation to daily occupational performance (CO-OP) approach has been effective in interventions for developmental coordination disorder (DCD). Based on an open-label, randomized controlled trial design, this study evaluated the effects of CO-OP on the occupational performance and motor skills of older kindergarten children with DCD-t using the School Assessment of Motor and Process Skills (S-AMPS) and the Movement Assessment Battery for Children, Second Edition. Children with a total DCDQ score of less than 40 or M-ABC2 scores in the 5th to 16th percentile were considered to have DCD-t. Furthermore, children with DCD-t and S-AMPS process skills less than 0.7 were considered to have DAMP (Deficits in Attention, Motor control and Perception)-t. After 3 months of CO-OP intervention, the performance and motor skills of children with DCD-t improved significantly. However, there were no significant changes noted in the motor skills of children with DAMP-t, although their occupational performance improved. These results suggest that CO-OP is effective even for older kindergarten children with DCD-t. However, further improvement of the CO-OP approach or a different strategy is required for children with ADHD comorbidity.

Cortical thickness is related to cognitive-motor automaticity and attention allocation in individuals with Alzheimer's disease: a regions of interest study

Alzheimer's disease (AD) is characterized by a distinct pattern of cortical thinning and resultant changes in cognition and function. These result in prominent deficits in cognitive-motor automaticity. The relationship between AD-related cortical thinning and decreased automaticity is not well-understood. We aimed to investigate the relationship between cortical thickness regions-of-interest (ROI) and automaticity and attention allocation in AD using hypothesis-driven and exploratory approaches. We performed an ROI analysis of 46 patients with AD. Data regarding MR images, demographic characteristics, cognitive-motor dual task performance, and cognition were extracted from medical records. Cortical thickness was calculated from MR T1 images using FreeSurfer. Data from the dual task assessment was used to calculate the combined dual task effect (cDTE), a measure of cognitive-motor automaticity, and the modified attention allocation index (mAAI). Four hierarchical multiple linear regression models were conducted regressing cDTE and mAAI separately on (1) hypothesis-generated ROIs and (2) exploratory ROIs. For cDTE, cortical thicknesses explained 20.5% (p = 0.014) and 25.9% (p = 0.002) variability in automaticity in the hypothesized ROI and exploratory models, respectively. The dorsal lateral prefrontal cortex (DLPFC) (β =  - 0.479, p = 0.018) and superior parietal cortex (SPC) (β = 0.467, p = 0.003), and were predictors of automaticity. For mAAI, cortical thicknesses explained 20.7% (p = 0.025) and 28.3% (p = 0.003) variability in attention allocation in the hypothesized ROI and exploratory models, respectively. Thinning of SPC and fusiform gyrus were associated with motor prioritization (β =  - 0.405, p = 0.013 and β =  - 0.632, p = 0.004, respectively), whereas thinning of the DLPFC was associated with cognitive prioritization (β = 0.523, p = 0.022). Cortical thinning in AD was related to cognitive-motor automaticity and task prioritization, particularly in the DLPFC and SPC. This suggests that these regions may play a primary role in automaticity and attentional strategy during dual-tasking.

Motor and cognitive dual-task performance under low and high task complexity in children with and without developmental coordination disorder

BACKGROUND

In everyday life, tasks are often performed simultaneously, which may be more difficult for children with developmental coordination disorder (DCD) than their peers.

AIMS

To examine (1) the effects of task complexity and type of concurrent task on dual-task performance in children with and without DCD; and (2) if the amount of effort that children put into the task performance differs between the groups.

METHODS

Participants were 64 children with and without DCD (aged 7-14 years). The dual-task paradigm consisted of a manual dexterity task of relatively low complexity (box and block test) or relatively high complexity (pegboard task), and a concurrent motor task (cycling task) or a concurrent cognitive task (word-listening task). To assess mental effort, children were asked how tired they felt before and after the experiment.

RESULTS

Dual-task interference was highest when the manual dexterity task of relatively high complexity was combined with the concurrent motor task. There were no group differences in dual-task interference, but children with DCD reported a larger increase in the level of tiredness after the experiment indicative of greater mental effort.

CONCLUSIONS

Depending on task demands, children with DCD are able to perform dual-tasks at the same level as their peers, but performance may take children with DCD more mental effort.

Developmental dyslexia, developmental coordination disorder and comorbidity discrimination using multimodal structural and functional neuroimaging

Developmental dyslexia (DD) and developmental coordination disorder (DCD) are two common neurodevelopmental disorders with a high co-occurrence rate. This led several authors to postulate that the two disorders share, at least partially, similar neural underpinning. However, even though several studies examined brain differences between typically developing (TD) children and children with either DD or DCD, no previous study directly compared DD, DCD and children with both disorders (COM) using neuroimaging. We acquired structural and resting-state functional MRI images of 136 children (TD = 42, DD = 45, DCD = 20, COM = 29). Difference between TD children and the other groups was assessed using univariate analysis of structural indexes including grey and white matter volumes and functional indexes quantifying activity (fraction of the amplitude of the low frequency fluctuations), local and global connectivity. Regional differences in structural and functional brain indexes were then used to train machine learning models to discriminate among DD, DCD and COM and to find the most discriminant regions. While no imaging index alone discriminated between the three groups, grouping grey and white matter volumes (structural model) or activity, local and global connectivity (functional model) made possible to discriminate among the DD, DCD and COM groups. The most important discrimination was obtained using the functional model, with regions in the cerebellum and the temporal lobe being the most discriminant for DCD and DD children, respectively. Results further showed that children with both DD and DCD have subtle but identifiable brain differences that can only be captured using several imaging indexes pertaining to both brain structure and function.

Efficacy of a Task-Oriented Intervention for Children with a Dual Diagnosis of Specific Learning Disabilities and Developmental Coordination Disorder: A Pilot Study

Background: Task-oriented approaches are recommended for children with developmental coordination disorder (DCD) to address deficits in motor performance and reduce activity limitations. Although this approach is used in several settings, the efficacy of these approaches in children with in dual-diagnosis of specific learning disabilities (SLD) and DCD is less widely known. This study aims to determine the effect of a group-based intervention based on neuromotor task training (NTT) principles on the motor performance of children aged 6–10 years with SLD/DCD. Methods: A pre-post-test controlled study design was conducted in children with a primary diagnosis of specific learning disabilities (SLD). DCD status was confirmed based on clinical assessment. Children scoring ≤16th percentile on the Motor Assessment Battery for Children 2nd Edition (MABC-2), who also presented with a functional motor problem, according to the MABC checklist were considered as having DCD. Children were allocated to the NTT intervention group based on teachers’ perceived notion of need and received two 45–60 min training sessions per week for nine weeks. Children allocated to the usual care (UC) group, received their planned occupational therapy and physical education. The MABC-2 was used to assess changes in motor performance. Outcome and Results: Our numbers confirm that it is crucial to identify the presence of motor coordination difficulties in children who have been diagnosed with SLD. A task-oriented training program based on NTT principles, presented in small groups, has a positive effect on the motor performance in learners with neurodevelopmental disorders and this effect was larger than in the usual care group. Conclusion and Implications: Although using a small group format in children with multiple neurodevelopmental disorders may be challenging for the therapists, it may be a way of delivering services to children in schools for special education. What this paper adds: Children with DCD plus LSD show improvement in their motor skills by performing group-based NTT in the school environment. Group-based NTT shows a significant improvement in the TSS score of the MABC-2 compared to usual care. Children with DCD plus SLD show equal effect sizes after NTT intervention as DCD without SLD.

Learning a novel rhythmic stepping task in children with probable developmental coordination disorder

BACKGROUND

Developmental coordination disorder affects approximately 6% of children, interfering with participation in physical activity and can persist through adulthood. However, no studies have investigated the neuromotor mechanisms of learning of a novel task with rhythmic cueing.

METHODS

Movement Assessment Battery for Children-2nd edition was used to identify 48 children with probable developmental coordination disorder (13.9 ± 0.05 yrs., 27% male) and 37 typically developed (13.9 ± 0.10 yrs., 54% male). While instrumented with an inertial measurement unit, both groups performed a novel rhythmic stepping task and with a concurrent auditory stroop test (dual-task), underwent seven weeks of intervention with step training with rhythmic cuing and were tested for retention five weeks post-intervention.

FINDINGS

Initially, the group with probable developmental coordination disorder had a higher variability of step timing (coefficient of variation: 0.08 ± 0.003-typically developed - 0.09 ± 0.004-probable developmental coordination disorder, p < 0.05) and a frequency of peak power spectral density further from the target 0.5 Hz (0.50 ± 0.002 Hz-typically developed - 0.51 ± 0.003 Hz-probable developmental coordination disorder, p < 0.05), and were more affected by the dual-task: power spectral density at 0.5 Hz (-7.2 ± 3.3%-typically developed - -13.4 ± 4.6%- prob_DCD, p < 0.05) and stroop test errors (6.4 ± 1.1%-typically developed - -11.1 ± 2.4%- probable developmental coordination disorder, p < 0.05). The intervention led to similar improvements in both groups in coefficient of variation of step timing (0.12 ± 0.01-Pre - 0.07 ± 0.002-Post, p < 0.05), frequency of the peak power spectral density (0.51 ± 0.005 Hz-Pre - 0.50 ± 0.001 Hz-Post, p < 0.05) and relative power spectral density bandpower (3.2 ± 0.2%-Pre - 5.9 ± 0.3%-Post, p < 0.05). All improvements were retained after five weeks post-training.

INTERPRETATION

Rhythmic cueing shows strong promise for enhancing motor learning in children with probable developmental coordination disorder.

TRIAL REGISTRATION

Retrospectively registered on ClinicalTrials.gov with reference: NCT03150784.

The Relationships between Self-Reported Motor Functioning and Autistic Traits: The Italian Version of the Adult Developmental Coordination Disorders/Dyspraxia Checklist (ADC)

BACKGROUND

We developed the Italian version of the adult developmental co-ordination disorders/dyspraxia checklist (ADC), providing reliability and concurrent validity data for the scale (Aim 1). In addition, we investigated the relationships between motor coordination difficulties and different autistic traits (Aim 2).

METHODS

498 participants (341 females; age range = 18-34) underwent the Italian version of the ADC, as well as a handwriting speed test, the autism spectrum quotient, the empathy quotient, and the systemizing quotient.

RESULTS

The distinction between three main factors (A, B, and C) identified in the original version of the ADC was confirmed here. Internal consistency of the ADC subscales was adequate, as well as the correlation with the handwriting speed test used to assess concurrent validity. No substantial sex differences on the ADC scores were found. Furthermore, data revealed that poor autistic-related communication skills and lower levels of systemizing tendencies were, among all the investigated autistic traits, those more strongly associated with higher motor coordination difficulties.

CONCLUSIONS

The Italian ADC seems a valuable tool for assessing motor coordination difficulties in adults and can reveal the nuanced impact exerted by different autistic traits on self-reported motor functioning.

Development of complex executive function over childhood: Longitudinal growth curve modeling of performance on the Groton Maze Learning Task

This longitudinal study modeled children's complex executive function (EF) development using the Groton Maze Learning Task (GMLT). Using a cohort-sequential design, 147 children (61 males, 5.5-11 years) were recruited from six multicultural primary schools in Melbourne and Perth, Australia. Race/ethnicity data were not available. Children were assessed on the GMLT at 6-month intervals over 2-years between 2010 and 2012. Growth curve models describe age-related change from 5.5 to 12.5 years old. Results showed a quadratic growth trajectory on each measure of error-that is, those that reflect visuospatial memory, executive control (or the ability to apply rules for action), and complex EF. The ability to apply rules for action, while a rate-limiting factor in complex EF, develops rapidly over early-to-mid childhood.

Does the Degree and/or Direction of Handedness in Children With Developmental Coordination Disorder Influence Motor and Cognitive Performance? A Pilot Study

Research has shown that nonright-handedness in children with developmental coordination disorder (DCD) is associated with poorer motor and cognitive performance. This study investigated the influence of degree and direction of handedness on performance using the Home Handedness Questionnaire, the Hit-the-Dot test, the Movement Assessment Battery for Children, and the digital Trail-Making Test. Eighteen children with DCD and 21 typically developing children aged 8–12 years participated in this study. The distribution of degree and direction of handedness in the group of DCD children were not different from that found in the typically developing group. In the Hit-the-Dot test, typically developing children significantly performed better than children with DCD, no matter which hand was dominant or to which degree. A significant inconsistent-handed advantage in the subdomain balance was found for children with DCD. Inconsistent handedness also seems to be an advantage for children with DCD on the digital Trail-Making Test performance. The relationship between the subcategories of the Movement Assessment Battery for Children and the digital Trail-Making Test part B is stronger for consistent than for inconsistent handedness. Our findings suggest that children with DCD and inconsistent handedness might benefit from greater crosstalk across hemispheres. In addition, these predispositions can be reinforced or discouraged throughout development and via occupational therapy.

Bibliometric analysis study on cognitive function in developmental coordination disorder from 2010 to 2022

Objective

To identify the research hotspots on cognitive function in developmental coordination disorder (DCD) in recent years, predict the research frontier and development trend, and provide more perspectives for the study of the DCD population.

Methods

Using CiteSpace and VOSviewer software to draw charts, 1,082 pieces of literature about DCD and cognitive function in the Web of Science core collection database from 2010 to 2022 were visually analyzed.

Results and conclusion

Interest in the cognitive function of DCD has been on the rise in the past 10 years. Over 40 countries and regions, 117 institutions and 200 researchers have participated in the corresponding research, mainly in the United States, and their institutions have published more highly influential results. The hot keywords are DCD, children, attention, working memory, performance, and attention-deficit/hyperactivity disorder (ADHD), and the main research hot topics include functional performance, population, cognitive psychology. The research directions include "DCD," "Asperger syndrome," "memory," "infant," "clumsiness," "neurodevelopmental disorder," "occupational therapy," "preschool children," "motor competence," "model," and "online control." Future research should focus on motor imagery and intrinsic models and use more neurophysiological techniques to reveal the cognitive characteristics of children with DCD and develop intervention programs.

Sensory Processing Impairments in Children with Developmental Coordination Disorder

The two objectives of this systematic review were to examine the following: (1) the difference in sensory processing areas (auditory, visual, vestibular, touch, proprioceptive, and multi-sensory) between children with and without developmental coordination disorder (DCD), and (2) the relationship between sensory processing and motor coordination in DCD. The following databases were comprehensively searched for relevant articles: PubMed, Science Direct, Web of Science, and Cochrane library. There were 1107 articles (published year = 2010 to 2021) found in the initial search. Full-text articles of all possibly relevant citations were obtained and inspected for suitability by two authors. The outcome measures were sensory processing impairments and their relationship with motor coordination. A total of 10 articles met the inclusion criteria. Children with DCD showed significant impairments in visual integration, tactile integration, proprioceptive integration, auditory integration, vestibular integration, and oral integration processes when compared with typically developing children. Evidence also supported that sensory processing impairments were associated with poor motor coordination in DCD. Preliminary support indicated that DCD have sensory processing impairments in visual, tactile, proprioceptive, auditory, and vestibular areas, which might contribute to participation restriction in motor activities. It is important to apply sensory integration therapy in rehabilitation programs for DCD in order to facilitate participation in daily activities.

Handwriting and Motor-Related Daily Performance among Adolescents with Dysgraphia and Their Impact on Physical Health-Related Quality of Life

Knowledge is limited about dysgraphia in adolescence and its association with daily motor-related daily performance and health-related quality of life (HRQOL). This study aimed to (1) compare and (2) examine correlations between handwriting measures, motor-related daily performance, and HRQOL of adolescents with and without dysgraphia and (3) examine the contribution of motor-related daily performance and handwriting measures to predict their physical HRQOL. There were eighty adolescents (13-18 yr): half with dysgraphia and half matched controls without dysgraphia per the Handwriting Proficiency Screening Questionnaire and Handwriting Legibility Scale participated. They copied a paragraph script onto a paper attached to the Computerized Penmanship Evaluation Tool digitizer and completed the World Health Organization Quality of Life Questionnaire-brief version and the Adult Developmental Coordination Disorder Checklist (ADC). We found significant between-group differences in motor-related daily performance, handwriting measures, and HRQOL and significant correlations between HRQOL and handwriting process measures and motor-coordination ability. Handwriting measures predicted 25%, and the ADC A and C subscales 45.6%, of the research group's physical QOL domain score variability. Notably, the control group's current perceptions of their motor-coordination performance (ADC-C) predicted 36.5% of the variance in physical QOL. Dysgraphia's negative effects during childhood and adolescence may reduce adolescents' HRQOL now and into adulthood.

Cognitive, perceptual, and motor profiles of school-aged children with developmental coordination disorder

Developmental coordination disorder (DCD) is a heterogeneous condition. Besides motor impairments, children with DCD often exhibit poor visual perceptual skills and executive functions. This study aimed to characterize the motor, perceptual, and cognitive profiles of children with DCD at the group level and in terms of subtypes. A total of 50 children with DCD and 31 typically developing (TD) peers (7–11 years old) underwent a comprehensive neuropsychological (15 tests) and motor (three subscales of the Movement Assessment Battery for Children-2) assessment. The percentage of children with DCD showing impairments in each measurement was first described. Hierarchical agglomerative and K-means iterative partitioning clustering analyses were then performed to distinguish the subtypes present among the complete sample of children (DCD and TD) in a data-driven way. Moderate to large percentages of children with DCD showed impaired executive functions (92%) and praxis (meaningless gestures and postures, 68%), as well as attentional (52%), visual perceptual (46%), and visuomotor (36%) skills. Clustering analyses identified five subtypes, four of them mainly consisting of children with DCD and one of TD children. These subtypes were characterized by: (i) generalized impairments (8 children with DCD), (ii) impaired manual dexterity, poor balance (static/dynamic), planning, and alertness (15 DCD and 1 TD child), (iii) impaired manual dexterity, cognitive inhibition, and poor visual perception (11 children with DCD), (iv) impaired manual dexterity and cognitive inhibition (15 DCD and 5 TD children), and (v) no impairment (25 TD and 1 child with DCD). Besides subtle differences, the motor and praxis measures did not enable to discriminate between the four subtypes of children with DCD. The subtypes were, however, characterized by distinct perceptual or cognitive impairments. These results highlight the importance of assessing exhaustively the perceptual and cognitive skills of children with DCD.

Lawrence K, Tachtsidis I, Tong Y, Torricelli A, Urner T, Wabnitz H, Wolf M, Wolf U, Xu S, Yang C, Yodh AG, Yücel MA, Zhou W. Optical imaging and spectroscopy for the study of the human brain: status report

This report is the second part of a comprehensive two-part series aimed at reviewing an extensive and diverse toolkit of novel methods to explore brain health and function. While the first report focused on neurophotonic tools mostly applicable to animal studies, here, we highlight optical spectroscopy and imaging methods relevant to noninvasive human brain studies. We outline current state-of-the-art technologies and software advances, explore the most recent impact of these technologies on neuroscience and clinical applications, identify the areas where innovation is needed, and provide an outlook for the future directions.

A Bibliometric and Visualization Analysis of Motor Learning in Preschoolers and Children over the Last 15 Years

Motor learning enables preschoolers and children to acquire fundamental skills that are critical to their development. The current study sought to conduct a bibliometric and visualization analysis to provide a comprehensive overview of motor-learning progress in preschoolers and children over the previous 15 years. The number of studies is constantly growing, with the United States and Australia, as well as other productive institutions and authors, at the leading edge. The dominant disciplines were Neurosciences and Neurology, Psychology, Rehabilitation, and Sport Sciences. The journals Developmental Medicine & Child Neurology, Human Movement Science, Physical Therapy, Neuropsychology, Journal of Motor Behavior, and Journal of Experimental Child Psychology have been the most productive and influential in this regard. The most common co-citations for clinical symptoms were for cerebral palsy, developmental coordination disorder, and autism. Research has focused on language impairment (speech disorders, explicit learning, and instructor-control feedback), as well as effective intervention strategies. Advances in brain mechanisms and diagnostic indicators, as well as new intervention and rehabilitation technologies (virtual reality, transcranial magnetic stimulation, and transcranial direct current stimulation), have shifted research frontiers and progress. The cognitive process is critical in intervention, rehabilitation, and new technology implementation and should not be overlooked. Overall, our broad overview identifies three major areas: brain mechanism research, clinical practice (intervention and rehabilitation), and new technology application.

Developmental Coordination Disorder and Most Prevalent Comorbidities: A Narrative Review

This narrative review describes, in detail, the relationships between Developmental Coordination Disorder (DCD) and most prevalent associated comorbidities in their complexity, heterogeneity and multifactoriality. The research has been conducted on the main scientific databases, excluding single case papers. Blurred borders between the different nosographic entities have been described and advances in this field have been highlighted. In this multifaceted framework a specific profiling for co-occurring DCD, ADHD and ASD signs and symptoms is proposed, confirming the need for a multidisciplinary approach to define new diagnostic paradigms in early childhood.

Infant motor behaviour and functional and cognitive outcome at school-age: A follow-up study in very high-risk children

BACKGROUND

The Infant Motor Profile (IMP) is an appropriate tool to assess and monitor infant motor behaviour over time. Infants at very high risk (VHR) due to a lesion of the brain generally show impaired motor development. They may grow into or out of their neurodevelopmental deficit.

AIMS

Evaluate associations between IMP-trajectories, summarised by IMP-scores in early infancy and rates of change, and functional and cognitive outcome at school-age in VHR-children.

STUDY DESIGN

Longitudinal study.

SUBJECTS

31 VHR-children, mainly due to a brain lesion, who had multiple IMP-assessments during infancy, were re-assessed at 7-10 years (school-age).

OUTCOME MEASURES

Functional outcome was assessed with the Vineland-II, cognition with RAKIT 2. Associations between IMP-trajectories and outcome were tested by multivariable linear regression analyses.

RESULTS

When corrected for sex, maternal education and follow-up age, initial scores of total IMP, variation and performance domains, as well as their rates of change were associated with better functional outcome (unstandardised coefficients [95% CI]): 36.44 [19.60-53.28], 33.46 [17.43-49.49], 16.52 [7.58-25.46], and 513.15 [262.51-763.79], 356.70 [148.24-565.15], and 269 [130.57-407.43], respectively. Positive rates of change in variation scores were associated with better cognition at school-age: 34.81 [16.58-53.03].

CONCLUSION

Our study indicated that in VHR-children IMP-trajectories were associated with functional outcome at school-age, and to a minor extent also with cognition. Initial IMP-scores presumably reflect the effect of an early brain lesion on brain functioning, whereas IMP rate of change reflects whether infants are able to grow into or out of their initial neurodevelopmental deficit.

Neuroergonomic assessment of developmental coordination disorder

Until recently, neural assessments of gross motor coordination could not reliably handle active tasks, particularly in realistic environments, and offered a narrow understanding of motor-cognition. By applying a comprehensive neuroergonomic approach using optical mobile neuroimaging, we probed the neural correlates of motor functioning in young people with Developmental Coordination Disorder (DCD), a motor-learning deficit affecting 5-6% of children with lifelong complications. Neural recordings using fNIRS were collected during active ambulatory behavioral task execution from 37 Typically Developed and 48 DCD Children who performed cognitive and physical tasks in both single and dual conditions. This is the first of its kind study targeting regions of prefrontal cortical dysfunction for identification of neuropathophysiology for DCD during realistic motor tasks and is one of the largest neuroimaging study (across all modalities) involving DCD. We demonstrated that DCD is a motor-cognitive disability, as gross motor /complex tasks revealed neuro-hemodynamic deficits and dysfunction within the right middle and superior frontal gyri of the prefrontal cortex through functional near infrared spectroscopy. Furthermore, by incorporating behavioral performance, decreased neural efficiency in these regions were revealed in children with DCD, specifically during motor tasks. Lastly, we provide a framework, evaluating disorder impact in ecologically valid contexts to identify when and for whom interventional approaches are most needed and open the door for precision therapies.

The effects of a visuo-motor and cognitive dual task on walking adaptability in children with and without Developmental Coordination Disorder

BACKGROUND

Children with Developmental Coordination Disorder (DCD-C) have motor coordination deficits which lead to difficulties in sports and play activities that require adaptations of the walking pattern. Sports and play often involve performing dual tasks, which affects performance in DCD-C more than in typically developing children (TD-C). So far, testing the impact of dual tasking on walking adaptability in DCD-C has received little scientific attention.

RESEARCH QUESTION

We tested the hypothesis that 6-12 year old DCD-C will show lower levels of walking adaptability than TD-C, and that due to problems with automatization this difference will increase when they are forced to divide their attention between tasks when a concurrent visuo-motor or cognitive task is added.

METHODS

Twenty-six DCD-C and sixty-nine TD-C were included in this cross-sectional study. They performed a challenging walking adaptability (WA) task on a treadmill as a single, a visuo-motor dual and a cognitive dual task at a pace of 3.5 km/h. Repeated measures ANCOVAs were performed with condition (single/dual task) as within-subjects factor, group (TD/DCD) as between-subjects factor, and age as covariate.

RESULTS

DCD-C performed poorer on the WA task than TD-C. The group differences increased when a concurrent visuo-motor task was added, but not when adding a concurrent cognitive task. A significant effect of age was found with younger children performing worse on all tasks.

SIGNIFICANCE

The results highlight the problems DCD-C have with walking adaptability and dual tasks, which capacities are essential for full participation in sports and play activities. Future research should investigate whether DCD-C may benefit from task-specific walking adaptability training.

Walking adaptability improves after treadmill training in children with Developmental Coordination Disorder: A proof-of-concept study

BACKGROUND

Children with Developmental Coordination Disorder (DCD) have motor coordination deficits leading to difficulties in sports and play that require adaptations of the walking pattern. Children with DCD indeed demonstrate poorer walking adaptability (WA) compared to typically developing children, but it remains elusive whether WA can be improved by training.

RESEARCH QUESTION

Does augmented-reality treadmill training lead to improvements in WA in children with DCD?

METHODS

Seventeen children with DCD were included in this proof-of-concept intervention study. They received a six-session training on the C-mill, a treadmill on which gait adjustments can be evoked by projected visual context. The effect of the training was evaluated before (M1), directly after training (M2) and after 6 months follow-up (M3) using the WAL-K (single and double run) and WA-tasks on the C-mill (as a single and with concurrent visuo-motor and cognitive task). In addition, parents completed a questionnaire on their perception of the training. Linear Mixed Model analyses were performed to assess the differences in WAL-K scores and success rates on the WA-tasks between M1-M2 and M1-M3.

RESULTS

Children significantly improved on the WAL-K double run and on all three WA-tasks between M1-M2 and M1-M3. Children did not improve on the WAL-K single run. Parents found the training useful and fun for their child and indicated that their child fell less frequently.

SIGNIFICANCE

The results show that C-mill training had positive and task-specific effects on WA in children with DCD, which effects generalized to an overground task and were retained at 6 months follow-up. This may help children with DCD to better participate in daily activities. Future research should include a control group to examine the effectiveness of the training program compared to receiving no training and may also examine the effect of the training on participation in daily life.

Behavioral and Neuroimaging Research on Developmental Coordination Disorder (DCD): A Combined Systematic Review and Meta-Analysis of Recent Findings

AIM

The neurocognitive basis of Developmental Coordination Disorder (DCD; or motor clumsiness) remains an issue of continued debate. This combined systematic review and meta-analysis provides a synthesis of recent experimental studies on the motor control, cognitive, and neural underpinnings of DCD.

METHODS

The review included all published work conducted since September 2016 and up to April 2021. One-hundred papers with a DCD-Control comparison were included, with 1,374 effect sizes entered into a multi-level meta-analysis.

RESULTS

The most profound deficits were shown in: voluntary gaze control during movement; cognitive-motor integration; practice-/context-dependent motor learning; internal modeling; more variable movement kinematics/kinetics; larger safety margins when locomoting, and atypical neural structure and function across sensori-motor and prefrontal regions.

INTERPRETATION

Taken together, these results on DCD suggest fundamental deficits in visual-motor mapping and cognitive-motor integration, and abnormal maturation of motor networks, but also areas of pragmatic compensation for motor control deficits. Implications for current theory, future research, and evidence-based practice are discussed.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO, identifier: CRD42020185444.

Feasibility and Preliminary Effects of a 1-Week Vestibular Rehabilitation Day Camp in Children with Developmental Coordination Disorder

AIM

This pilot study investigated the feasibility and preliminary effects of an intensive 1-week day camp program for children with Developmental Coordination Disorder (DCD) that focused on vestibular rehabilitation.

METHODS

Ten participants (6-10 years) were assessed twice pre-intervention, post intervention, and at 8-week follow-up. Videonystagmography, Video Head Impulse Tests (vHIT), and Modified Emory Clinical Vestibular Chair Test (m-ECVCT) test were assessed at baseline. Outcomes measures were gaze stability (Dynamic Visual Acuity; DVA), functional gait (Functional Gait Assessment; FGA), balance (Sensory Organization Test), motor function (Bruininks-Oseretsky Test), and participation (Miller Function and Participation).

RESULTS

No abnormal results were detected from the videonystagmography, vHIT and m-ECVCT. There was a 100% attendance rate at the camp and assessment sessions. FGA scores significantly improved following intervention and changes were maintained at follow-up. The number of children with abnormal DVA scores decreased from 3 to 1 to 0 between pre-intervention, post-intervention, and follow-up. There were no significant changes in any of the other outcomes following intervention.

CONCLUSIONS

Intensive vestibular rehabilitation delivered in a day camp format is feasible and show positive preliminary effects on functional gait and dynamic visual acuity in children with DCD.

A sensorimotor representation impairment in dyslexic adults: A specific profile of comorbidy

Sensorimotor disorders have been frequently reported in children and adults with dyslexia over the past 30 years. The present study aimed to determine the impact of sensorimotor comorbidity risks in dyslexia by investigating the functional links between phonological and sensorimotor representations in young dyslexic adults. Using 52 dyslexic participants and 58 normo-readers, we investigated whether the underlying phonological deficit, which is reported in the literature, was associated with a general impairment of sensorimotor representations of articulatory and bodily actions. Internal action representations were explored through motor imagery tasks, consisting of measuring and comparing the durations of performed or imagined actions chosen from their current repertoire of daily life activities. To detect sensorimotor deficits, all participants completed the extended version of the M-ABC 2, as a reference test. We found sensorimotor impairments in 27% of the young adult dyslexics, then considered as sensorimotor comorbid, as opposed to much less in the normo-reader group (5%). While motor slowdown, reflecting motor difficulty, was present in all dyslexic adults, motor imagery performance was impacted only in the specific dyslexic subgroup with sensorimotor impairments. Moreover, in contrast with slowness, only the comorbid subgroup showed an increased variability in execution durations. The present study highlights the importance of the quality of perception-action coupling, questions the relevance of investigating sensorimotor impairment profiles beyond phonological deficits and provides new arguments supporting the perspective of multiple deficits approaches in dyslexia.

Specific Cues Can Improve Procedural Learning and Retention in Developmental Coordination Disorder and/or Developmental Dyslexia

The present study investigates procedural learning of motor sequences in children with developmental coordination disorder (DCD) and/or developmental dyslexia (DD), typically-developing children (TD) and healthy adults with a special emphasis on (1) the role of the nature of stimuli and (2) the neuropsychological functions associated to final performance of the sequence. Seventy children and ten adults participated in this study and were separated in five experimental groups: TD, DCD, DD, and DCD + DD children and adults. Procedural learning was assessed with a serial reaction time task (SRTT) that required to tap on a specific key as accurately and quickly as possible when stimuli appeared on the screen. Three types of stimuli were proposed as cues: the classical version of the SRTT with 4 squares aligned horizontally on the screen, giving visuospatial cues (VS cues), and two modified versions, with 4 letters aligned horizontally on the screen (VS + L cues) and letters at the center of the screen (L cues). Reaction times (RT) during the repeated and random blocks allowed assessing three phases of learning: global learning, specific learning and retention of the sequence. Learning was considered as completed when RT evolved significantly in the three phases. Neuropsychological assessment involved, among other functions, memory and attentional functions. Our main result was that learning and retention were not influenced by the available cues in adults whereas learning improved with specific cues in children with or without neurodevelopmental disorders. More precisely, learning was not completed with L cues in children with neurodevelopmental disorders. For children with DD, learning was completed with the VS and VS + L cues whereas for children with DCD (with or without DD), learning was completed with combined VS + L cues. Comorbidity between DD and DCD had no more impact on procedural learning than DCD alone. These results suggest that learning depends on the nature of cues available during practice and that cues allowing learning and retention depend on the type of disorder. Moreover, selective attention was correlated with RT during retention, suggesting that this neuropsychological function is important for procedural learning whatever the available cues.

Subcortical brain structure in children with developmental coordination disorder: A T1-weighted volumetric study

Developmental coordination disorder (DCD) is a neurodevelopmental disorder occurring in 5-6% of school-aged children. Converging evidence suggests that dysfunction within cortico-striatal and cortico-cerebellar networks may contribute to motor deficits in DCD, yet limited research has examined the brain morphology of these regions. Using T1-weighted magnetic resonance imaging the current study investigated cortical and subcortical volumes in 37 children with DCD, aged 8 to 12 years, and 48 controls of a similar age. Regional brain volumes of the thalamus, basal ganglia, cerebellum and primary motor and sensory cortices were extracted using the FreeSurfer recon-all pipeline and compared between groups. Reduced volumes within both the left and right pallidum (Left: F = 4.43, p = 0.039; Right: F = 5.24, p = 0.025) were observed in children with DCD; however, these results did not withstand correction for multiple comparisons. These findings provide preliminary evidence of altered subcortical brain structure in DCD. Future studies that examine the morphology of these subcortical regions are highly encouraged in order replicate these findings.

Rhythm and timing as vulnerabilities in neurodevelopmental disorders

Millions of children are impacted by neurodevelopmental disorders (NDDs), which unfold early in life, have varying genetic etiologies and can involve a variety of specific or generalized impairments in social, cognitive and motor functioning requiring potentially lifelong specialized supports. While specific disorders vary in their domain of primary deficit (e.g. autism spectrum disorder (social), attention-deficit/hyperactivity disorder (attention), developmental coordination disorder (motor) and developmental language disorder (language)), comorbidities between NDDs are common. Intriguingly, many NDDs are associated with difficulties in skills related to rhythm, timing and synchrony though specific profiles of rhythm/timing impairments vary across disorders. Impairments in rhythm/timing may instantiate vulnerabilities for a variety of NDDs and may contribute to both the primary symptoms of each disorder as well as the high levels of comorbidities across disorders. Drawing upon genetic, neural, behavioural and interpersonal constructs across disorders, we consider how disrupted rhythm and timing skills early in life may contribute to atypical developmental cascades that involve overlapping symptoms within the context of a disorder's primary deficits. Consideration of the developmental context, as well as common and unique aspects of the phenotypes of different NDDs, will inform experimental designs to test this hypothesis including via potential mechanistic intervention approaches. This article is part of the theme issue 'Synchrony and rhythm interaction: from the brain to behavioural ecology'.

Pediatric care for children with Developmental Coordination Disorder, can we do better?

This paper adopts a method of narrative critical review based on a non-systematic search of the literature to provide insights into the trends of developmental coordination disorder (DCD) treatment and to point out some future alternative approaches to prevent secondary health implications in children with DCD. The cause of DCD is unknown, but evidence suggests that these children have atypical brain structure and function. Interventions to help children cope with their activity limitations are effective in improving motor competence and motor skill related fitness in the short term. Although activity-orientated interventions can improve motor outcomes in children with DCD, high quality intervention trials and evaluation of long-term effects are urgently needed. Importantly, motor coordination problems associated with DCD extend to exercise-related activities leading to reduced participation in play and sports, which causes secondary problems in muscular fitness and body composition. Hence, treatment goals should not be limited to the improvement of motor skills (in ADL), but should also focus on health-related quality of life. We therefore propose when noticing motor problems in a child, already before enrolling but also during intervention, to explore ways to adapt everyday physical activities to optimally match the child's skill level. Hence, such activities will not only train the skills and improve physical fitness but will lead to positive engagement, thereby preventing the child from opting out of active play and sports. This provides the child with chances for exercise-dependent learning and will also positively impact social-emotional well-being.

Effect of dual tasking on a dynamic balance task in children with and without DCD

The purpose of this study was to compare performance of children with Developmental Coordination Disorder (DCD) and typically developing (TD) children in a dual task paradigm with a dynamic balance task on the Wii Fit as primary task and a concurrent cognitive (counting) or a concurrent bimanual fine motor task as secondary tasks. Using a cross-sectional design, 25 children with DCD and 38 TD children were assessed with the Movement Assessment Battery for Children, 2nd edition (MABC-2) and Divided Attention (DA) task of the KiTAP. Next, the single- and dual-tasks were performed and the level of interference or facilitation of the dual tasks was calculated. Regression analysis determined the predictive value of the DA and MABC-2 component balance outcomes on the dual task performance. On the motor and attentional tasks, the group of children with DCD scored significantly below the level of the TD children. The dual task effect showed similar interference and facilitation of tasks in the different dual-task conditions in both groups. In the dual task-cognitive condition, the divided attention abilities and the MABC-2 balance score predicted 25% of the Wii Fit dynamic balance task performance, whereas in the dual task-motor condition this was higher (31.6%). In both conditions, DA was a stronger predictor than MABC balance score and appears to be an important factor to consider when developing motor task training for children with DCD.

Qualitative and Quantitative Assessment of Overarm Throwing in Children With and Without Developmental Coordination Disorder

Background: Children with developmental coordination disorder (DCD) frequently have difficulties performing gross motor skills such as the overarm throw. Our study examines the differences in both qualitative and quantitative characteristics of overarm throwing for accuracy between typically developing (TD) and children with DCD. Methods: A total of 74 children (36 females/38 males) aged between 7 and 11 years, participated in this study. The authors used the Movement Assessment Battery for Children—second edition to assess motor impairment. In total, 37 (50%) met the criteria for DCD. Each participant completed 10 overarm throws for accuracy at a target. The authors assessed movement quality using the component approach (Roberton & Halverson, 1984) and quantity using target accuracy. Results: The analyses revealed significantly lower throwing accuracy in DCD versus TD children. Children with DCD also demonstrated fewer component combinations and lower developmental levels than their TD peers. Finally, product scores tracked with process scores. Discussion: Both qualitative and quantitative measures clearly showed that children with DCD are at a disadvantage in controlling a ball during overarm throwing. They used stability profiles that limited coordination variability. TD participants performed more combinations of higher developmental levels to achieve more accurate throws, suggesting they controlled variability to optimize the accuracy of their throws.

Second-order motor planning difficulties in children with developmental coordination disorder

The second-order motor planning ability of children with developmental coordination disorder (DCD) has often been studied using tasks that require judgements of end-state comfort (ESC). In these studies, children may have chosen to prioritize other aspects of performance (e.g., a comfortable start-posture) over ESC while still being able to complete the goal of the task. This is a limitation that is inherent to previously used ESC paradigms. To avoid this in the present study, 52 children with and without DCD (aged 5-12 years) completed a task that requires second-order motor planning for its successful completion. In the hexagonal knob task, children were instructed to grasp and rotate a hexagonal knob. The rotation angle varied in size: 60°, 120°, 180°, and 240° rotations. Both the 180° and 240° rotation conditions required an uncomfortable starting posture for successful task completion. Results showed that children with DCD were less likely to adjust their initial grip in anticipation of the required rotation angle, resulting in more task failures compared with typically developing (TD) children. Based on this finding we conclude that children with DCD experience genuine second-order motor planning difficulties. Analysis of temporal outcomes, showed that initial reaction time increased with rotation angle, but this was less pronounced for children with DCD than for TD children. There were no between group differences in timing of subsequent events. These results suggest that the difficulties of children with DCD are related to the initial planning process, that is, before the start of the movement.

The Neurological Basis of Developmental Dyslexia and Related Disorders: A Reappraisal of the Temporal Hypothesis, Twenty Years on

In a now-classic article published a couple of decades ago (Brain, 2000; 123: 2373-2399), I proposed an "extended temporal processing deficit hypothesis of dyslexia", suggesting that a deficit in temporal processing could explain not only language-related peculiarities usually noticed in dyslexic children, but also a wider range of symptoms related to impaired processing of time in general. In the present review paper, I will revisit this "historical" hypothesis both in the light of a new clinical perspective, including the central yet poorly explained notion of comorbidity, and also taking a new look at the most recent experimental work, mainly focusing on brain imaging data. First, consistent with daily clinical practice, I propose to distinguish three groups of children who fail to learn to read, of fairly equal occurrence, who share the same initial presentation (difficulty in mastering the rules of grapheme-phoneme correspondence) but with differing associated signs and/or comorbid conditions (language disorders in the first group, attentional deficits in the second one, and motor coordination problems in the last one), thus suggesting, at least in part, potentially different triggering mechanisms. It is then suggested, in the light of brain imaging information available to date, that the three main clinical presentations/associations of cognitive impairments that compromise reading skills acquisition correspond to three distinct patterns of miswiring or "disconnectivity" in specific brain networks which have in common their involvement in the process of learning and their heavy reliance on temporal features of information processing. With reference to the classic temporal processing deficit of dyslexia and to recent evidence of an inability of the dyslexic brain to achieve adequate coupling of oscillatory brain activity to the temporal features of external events, a general model is proposed according to which a common mechanism of temporal uncoupling between various disconnected-and/or mis-wired-processors may account for distinct forms of specific learning disorders, with reading impairment being a more or less constant feature. Finally, the potential therapeutic implications of such a view are considered, with special emphasis on methods seeking to enhance cross-modal connectivity between separate brain systems, including those using rhythmic and musical training in dyslexic patients.

Mental rotation performance in young adults with and without developmental coordination disorder

While there have been consistent behavioural reports of atypical hand rotation task (HRT) performance in adults with developmental coordination disorder (DCD), this study aimed to clarify whether this deficit could be attributed to specific difficulties in motor imagery (MI), as opposed to broad deficits in general mental rotation. Participants were 57 young adults aged 18-30 years with (n = 22) and without DCD (n = 35). Participants were compared on the HRT, a measure of MI, and the letter number rotation task (LNRT), a common visual imagery task. Only participants whose behavioural performance on the HRT suggested use of a MI strategy were included in group comparisons. Young adults with DCD were significantly less efficient compared to controls when completing the HRT yet showed comparable performance on the LNRT relative to adults with typical motor ability. Our data are consistent with the view that atypical HRT performance in adults with DCD is likely to be attributed to specific difficulties engaging in MI, as opposed to deficits in general mental rotation. Based on the theory that MI provides insight into the integrity of internal action representations, these findings offer further support for the internal modelling deficit hypothesis of DCD.

The Developing Human Connectome Project: typical and disrupted perinatal functional connectivity

The Developing Human Connectome Project is an Open Science project that provides the first large sample of neonatal functional MRI data with high temporal and spatial resolution. These data enable mapping of intrinsic functional connectivity between spatially distributed brain regions under normal and adverse perinatal circumstances, offering a framework to study the ontogeny of large-scale brain organization in humans. Here, we characterize in unprecedented detail the maturation and integrity of resting state networks (RSNs) at term-equivalent age in 337 infants (including 65 born preterm). First, we applied group independent component analysis to define 11 RSNs in term-born infants scanned at 43.5–44.5 weeks postmenstrual age (PMA). Adult-like topography was observed in RSNs encompassing primary sensorimotor, visual and auditory cortices. Among six higher-order, association RSNs, analogues of the adult networks for language and ocular control were identified, but a complete default mode network precursor was not. Next, we regressed the subject-level datasets from an independent cohort of infants scanned at 37–43.5 weeks PMA against the group-level RSNs to test for the effects of age, sex and preterm birth. Brain mapping in term-born infants revealed areas of positive association with age across four of six association RSNs, indicating active maturation in functional connectivity from 37 to 43.5 weeks PMA. Female infants showed increased connectivity in inferotemporal regions of the visual association network. Preterm birth was associated with striking impairments of functional connectivity across all RSNs in a dose-dependent manner; conversely, connectivity of the superior parietal lobules within the lateral motor network was abnormally increased in preterm infants, suggesting a possible mechanism for specific difficulties such as developmental coordination disorder, which occur frequently in preterm children. Overall, we found a robust, modular, symmetrical functional brain organization at normal term age. A complete set of adult-equivalent primary RSNs is already instated, alongside emerging connectivity in immature association RSNs, consistent with a primary-to-higher order ontogenetic sequence of brain development. The early developmental disruption imposed by preterm birth is associated with extensive alterations in functional connectivity.