Mathematical difficulties in developmental coordination disorder: Symbolic and nonsymbolic number processing

Finger counting to relieve working memory in children with developmental coordination disorder: Insights from behavioral and three-dimensional motion analyses

A limited number of studies have attempted to understand how motor deficits affect numerical abilities in children with developmental coordination disorder (DCD). The purpose of this study was to explore the functionality of finger-counting (FC) in children with DCD. The participants, 15 children with DCD and 15 typically developing (TD) children matched on school level and fluid reasoning abilities, were asked to use FC to solve an ordinal task with high working memory (WM) load. Behavioral measures supplemented with biomechanical measures, from three-dimensional motion analysis synchronized to a voice recording were used to assess children's performance and FC functionality (total duration, inter-finger [IF] transition, IF variance, finger/voice synchronization, and automatization of FC movements). Children with DCD were less accurate than TD children in using FC to solve ordinal problems with high WM load. This group difference could not be accounted for by poor FC skills given that FC movement turned out to be as functional in children with DCD as in their TD peers. When added to the model as a covariate, WM captured a greater proportion of intergroup variability than manual dexterity, further suggesting that their difficulties would be better accounted for by limited WM resources than by fine motor skills.

Maths performance of adults with and without developmental coordination disorder (DCD): The role of working memory and maths anxiety

Previous studies have shown that children with Developmental Coordination Disorder (DCD)/Dyspraxia have poorer maths performance compared to their neurotypical (NT) counterparts. However, no studies have explored the cognitive and emotional factors affecting the maths performance of adults with DCD. This study, therefore, investigated the role of working memory (WM), maths anxiety (MAS), and maths self-efficacy on the maths performance of adults with DCD. We found that adults with DCD had lower WM and maths performance and were more maths anxious than their NT peers. However, there were no significant differences in maths self-efficacy. When looking at the predictors of maths performance, we found a positive relationship between WM resources and the DCD maths performance, possibly indicating that they relied more on WM resources to perform simple mental arithmetic tasks than NTs. On the other hand, MAS had an inverse relationship with the NT maths performance but not with the DCD performance. The reasons and implications of these findings will be discussed.

Sensorimotor mechanisms selective to numerosity derived from individual differences

We have previously shown that after few seconds of adaptation by finger-tapping, the perceived numerosity of spatial arrays and temporal sequences of visual objects displayed near the tapping region is increased or decreased, implying the existence of a sensorimotor numerosity system (Anobile et al., 2016). To date, this mechanism has been evidenced only by adaptation. Here, we extend our finding by leveraging on a well-established covariance technique, used to unveil and characterize 'channels' for basic visual features such as colour, motion, contrast, and spatial frequency. Participants were required to press rapidly a key a specific number of times, without counting. We then correlated the precision of reproduction for various target number presses between participants. The results showed high positive correlations for nearby target numbers, scaling down with numerical distance, implying tuning selectivity. Factor analysis identified two factors, one for low and the other for higher numbers. Principal component analysis revealed two bell-shaped covariance channels, peaking at different numerical values. Two control experiments ruled out the role of non-numerical strategies based on tapping frequency and response duration. These results reinforce our previous reports based on adaptation, and further suggest the existence of at least two sensorimotor number channels responsible for translating symbolic numbers into action sequences.

Factors associated with mathematical capacity in children with Developmental Coordination Disorder

BACKGROUND

Developmental Coordination Disorder (DCD) is a condition characterized by difficulties in motor planning and coordination and affects 5 to 6% of all school-aged children. Children with DCD frequently present with difficulties with academic activities such as handwriting. However, no study to date has comprehensively described mathematical capacity and its potential associated factors in this high-risk group.

AIMS

We aimed to describe the frequency and nature of mathematical difficulties of school-aged children with DCD and to evaluate potential factors associated with mathematical performance.

METHODS

A total of 55 elementary school-aged children with DCD underwent comprehensive standardized assessments of mathematical, visuoperceptual (VP), attentional, visual-motor integration (VMI), and motor skills. The contribution of each factor to mathematical capacity was established using hierarchical multivariate linear regression models.

RESULTS

Children with DCD (9.1 ± 1.5 years, 44 males) had lower overall mathematical capacity compared to normative data (-0.59 SD) on the KeyMath 3rd edition, with poorer performance in basic concepts and problem-solving. Thirty-eight percent of the sample performed below the 15th percentile in overall mathematical skills. VP skills were the most important factors associated with most mathematical domains. Thirty-four percent of the variance of overall mathematical capacity was explained by VP skills, inattention, VMI and motor impairments while controlling for household income (F [5,49]=5.029, p < .0001).

CONCLUSION

Children with DCD present with mathematical difficulties in basic concepts and problem-solving, which are partially explained by VP skills. Our findings stress the important of systematically assessing mathematical difficulties children with DCD to ensure they receive the necessary support that leads to academic success.

A number sense as an emergent property of the manipulating brain

The ability to understand and manipulate numbers and quantities emerges during childhood, but the mechanism through which humans acquire and develop this ability is still poorly understood. We explore this question through a model, assuming that the learner is able to pick up and place small objects from, and to, locations of its choosing, and will spontaneously engage in such undirected manipulation. We further assume that the learner's visual system will monitor the changing arrangements of objects in the scene and will learn to predict the effects of each action by comparing perception with a supervisory signal from the motor system. We model perception using standard deep networks for feature extraction and classification. Our main finding is that, from learning the task of action prediction, an unexpected image representation emerges exhibiting regularities that foreshadow the perception and representation of numbers and quantity. These include distinct categories for zero and the first few natural numbers, a strict ordering of the numbers, and a one-dimensional signal that correlates with numerical quantity. As a result, our model acquires the ability to estimate numerosity, i.e. the number of objects in the scene, as well as subitization, i.e. the ability to recognize at a glance the exact number of objects in small scenes. Remarkably, subitization and numerosity estimation extrapolate to scenes containing many objects, far beyond the three objects used during training. We conclude that important aspects of a facility with numbers and quantities may be learned with supervision from a simple pre-training task. Our observations suggest that cross-modal learning is a powerful learning mechanism that may be harnessed in artificial intelligence.

Impact of developmental coordination disorder in childhood on educational outcomes in adulthood among neonatal intensive care recipients: a register-based longitudinal cohort study

OBJECTIVES

Developmental coordination disorder (DCD) is related to poorer educational outcomes among children and adolescents. Evidence on this association into adulthood is lacking. Therefore, we aimed to investigate whether probable DCD (pDCD) in childhood affected educational outcomes among adults, and whether this was affected by sex or a co-occurring attention deficit in childhood.

DESIGN

Register-based longitudinal cohort study.

SETTING

Neonatal intensive care (NIC) recipients born at Uppsala University Children's Hospital, Uppsala, Sweden, from 1986 to 1989 until they reached the age of 28.

PARTICIPANTS

185 NIC recipients.

PRIMARY AND SECONDARY OUTCOME MEASURES

At the age of 6.5, 46 (24.6%) of the NIC recipients were diagnosed with pDCD. Using register-based longitudinal data, we compared participants with and without pDCD in terms of: (1) age at Upper Secondary School (USS) graduation, and (2) highest level of education achieved by age 28.

RESULTS

The median age at USS graduation was 19 years, with similar graduation ages and ranges between those with or without pDCD. However, a higher proportion of participants without pDCD had graduated from USS at ages 19 and 24. By age 29, most participants had completed USS. At age 28, 33% of participants had attained a bachelor's or master's degree. Although there was no significant difference between the groups, the proportion that had attained a degree was higher among those without pDCD and women without pDCD had achieved the highest level of education. Educational outcomes remained similar for those with pDCD, regardless of childhood attention deficit.

CONCLUSIONS

pDCD during childhood may have a lasting impact on educational outcomes, particularly among women. Raising awareness of DCD among parents, health and educational professionals is vital for early identification and the provision of appropriate support and interventions in schools, mitigating the potential negative consequences associated with DCD and promoting positive educational outcomes.

Effectiveness of Psychomotor Therapy among Children with Graphomotor Impairment with and without DCD-Diagnosis

In Switzerland, psychomotor therapy (PMT) is a standard treatment for children with graphomotor impairments, but scientific evidence of its effectiveness is rare. To investigate the effectiveness of PMT, we conducted a randomised field trial (RFT). The sample consisted of 121 first and second graders with graphomotor impairments, some of whom met the criteria of developmental coordination disorder, while the remaining suffered from developmental dysgraphia. The treatments lasted over 5 months. Handwriting fluency and consistency were measured five times on a digitising tablet. All participating children completed a self-concept interview, and a standardised fine motor performance test twice. Psychomotor therapy significantly improved the fine motor skills of the therapy group compared to those of the waiting group. However, there was no evidence that the treated children improved more than the waiting children in terms of their graphomotor skills such as frequency, automaticity, and consistency of forming letters. Finally, the children of the therapy group showed partial improvements in their handwriting self-concept, while those of the waiting group children remained stable. This short-term RFT demonstrated the effectiveness of PMT in terms of fine motor skills and some aspects of the handwriting self-concept but showed no effects on handwriting fluency and consistency.

Cognition and maths in children with Attention-Deficit/Hyperactivity disorder with and without co-occurring movement difficulties

BACKGROUND

Movement difficulties are common in ADHD, however, the implications of their co-occurrences on cognitive and maths performance is unknown.

AIMS

This study set out to examine whether cognitive and maths performance of children with high ADHD symptoms differs depending on the co-occurrence of movement difficulties given evidence that weaker visuospatial processing, known to be important for maths performance, differentiates ADHD and DCD. We also aimed to examine whether relationships between cognition and maths in ADHD differs depending on co-occurring movement difficulties.

METHODS

Participants were 43 drug naïve children between 6 and 12 years old (M = 101.53 months SD = 19.58). The ADHD-only group (n = 18) included children with high ADHD scores, and those in the ADHD+DCD group (n = 25) concurrently had high movement difficulty scores. All completed executive function and memory, including 2 visuo-spatial memory tasks from the CANTAB battery and Mathematics Problem Solving, Numeracy, and Maths Fluency tasks from the WIAT-III and specific factual, conceptual, and procedural maths component tasks.

RESULTS

Children in the ADHD+DCD group scored significantly lower on visuospatial working memory (WM) capacity, than those in the ADHD-only group. Both groups were comparable on all other cognitive assessments of executive functions, memory, and processing speed. The groups did not differ in their maths attainment scores, nor on more specific maths skills. Comparison of the correlations between cognitive processes and maths revealed that the association between visuospatial WM updating and procedural skill efficiency was stronger for the ADHD-only group. Moreover, associations between visuospatial WM and maths problem solving attainment were stronger in the ADHD+DCD group.

CONCLUSIONS

Despite similarities in maths performance, children with ADHD+DCD could be distinguished by lower visuospatial WM. Differential associations with some of the maths domain implicate recruitment of different cognitive processes for some aspects of maths. This distinction can be particularly useful for conceptualising cognitive characteristics of different clinical groups and understanding cognitive pathways of maths difficulties. Implications for interventions are discussed.

Academic Challenges in Developmental Coordination Disorder: A Systematic Review and Meta-Analysis

AIMS

Developmental Coordination Disorder (DCD) is a chronic condition affecting motor coordination in daily activities. While motor difficulties are well documented in this population, it is unclear how frequent and to what extent academic activities are affected. This systematic review aims to comprehensively summarize the knowledge regarding the prevalence and extent of academic difficulties in reading, writing and mathematics in school-aged children with DCD.

METHODS

Two independent reviewers analyzed original studies on academic difficulties in school-aged children with DCD. A binary random-effects model was used to calculate the pooled prevalence by academic difficulty. A random-effects model using standardized mean differences (g statistic) was calculated to estimate the extent of the academic difficulties.

RESULTS

Twenty-four studies were included. A pooled prevalence of 84% of handwriting difficulties and 89.5% of mathematical difficulties was reported. No pooled prevalence of difficulties could be calculated for the other academic outcomes. Children with DCD present with poorer performance in handwriting legibility (g = -1.312) and speed (g = -0.931), writing (g = -0.859), mathematics (g = -1.199) and reading (g = -1.193).

CONCLUSIONS

This review highlights the high frequency and severity of academic difficulties in children with DCD, specifically in mathematics, which stresses the importance of evaluating academic performance to target interventions to support optimal functioning in daily life.

Do executive functions and gross motor skills predict writing and mathematical performance in children with developmental coordination disorder?

Aim: To examine whether executive functions, and gross motor skills were predictors for school performance in children with DCD, with risk for DCD (r-DCD), and with typical development (TD).Methods: Participants were 63 children with DCD (M_age = 8.70, SD_age = .64), 31 children with r-DCD (M_age = 8.90, SD_age = 0.74), and 63 typical development children (M_age = 8.74, SD_age = .63). Wechsler Abbreviated Scale of Intelligence, Movement Assessment Battery for Children-2, Test of Gross Motor Development-3, Oral Word Span in Sentences, Odd-One-Out, Go/No-Go, Hayling Test, Trail Making Test, Five Digits Test, and the Test of School Performance-II were utilized.Results: In DCD, processing speed (β = -.42, p = .005), and auditory-motor inhibition (β = -.36, p = .009), and auditory-verbal inhibition (β = -.38, p = .023) predicted math performance; and auditory-motor (β = -.40, p = .38) and visuospatial working memory (β = -.33 p = .011) predicted writing performance. In r-DCD, auditory-motor (β = - .67; p = .002) and visual-motor (β = -.40; p = .040) inhibition predicted math performance; visual-motor inhibition predicted writing performance (β = -.47; p = .015).Conclusion: Lower inhibitory control and visuospatial working memory scores affect children with DCD and r-DCD' school performance.

Evaluating the Factor Structure and Criterion Validity of the Canadian Little DCDQ: Associations Between Motor Competence, Executive Functions, Early Numeracy Skills, and ADHD in Early Childhood

The Canadian Little Developmental Coordination Disorder Questionnaire (Little DCDQ-CA) is a parent-report screening instrument that identifies 3- to 4-year-old children who may be at risk for Developmental Coordination Disorder (DCD). We tested the factor structure and criterion validity of the Little DCDQ-CA in a sample of preschool-aged children in the United States (N = 233). Factor analysis indicated that the DCDQ-CA was best represented by one factor. Using cutoff scores that were proposed by the developer, 45% of the sample was identified as at-risk for DCD. Although a much larger percentage of children was identified as at-risk than would be expected based on the prevalence of formal DCD diagnoses in the population, the Little DCDQ-CA demonstrated good criterion validity. Specifically, compared with their peers, children who exceeded the at-risk criterion demonstrated worse motor competence, executive functioning skills, and early numeracy skills and were rated as having greater ADHD behaviors by their teachers, all consistent with expectations for children who are at risk for DCD. Results are discussed as they relate to future use of the Little DCDQ-CA.

International clinical practice recommendations on the definition, diagnosis, assessment, intervention, and psychosocial aspects of developmental coordination disorder - Chinese (Mandarin) translation

目的

本国际临床指南由欧洲残疾儿童学会（the European Academy of Childhood Disability，EACD）牵头制定，旨在解决发育性协调障碍（developmental coordination disorder，DCD）的定义、诊断、评估、干预以及与社会心理方面的临床应用关键问题。

方法

本指南针对五个领域的关键问题，通过文献综述和专家团队的正式讨论达成共识。为保证指南的循证基础，以“机制”、“评估”和“干预”为检索词, 对2012年更新以来提出的最新建议以及新增的“社会心理问题”和“青少年/成人”为检索词进行检索。根据牛津大学循证医学中心证据等级 (证据水平 [level of evidence, LOE]1–4) 将结果进行分类，最终转化为指南建议。并由国际、多学科专家小组举行了两次会议，5个回合的Delphi 专家问卷调查，制定了高质量临床应用实践 (good clinical practice，GCP) 。

结果

本指南共制定35条建议。其中8条以文献综述为依据 (3 条涉及“评估”，5条涉及“干预”)； 22 条在 2012 年指南的基础上进行了更新；其他为涉及诊断、评估 (3条GCP) 及社会心理问题 (2 条 GCP) 的新建议。此外，其中有1条(LOE)新建议提出视频游戏可作为以活动和参与为导向的传统干预措施的辅助手段，并针对青少年和成人DCD提出了 2 条新建议 (1 条 GCP，1 条 LOE)。

结论

本指南是基于当前的研究证据和专家共识对DCD进行全面概述。它反映了不同学科临床和科研人员的最新科技水平。本国际指南可作为各国制定指南的基础。

How visual is the « number sense »? Insights from the blind

Is vision a necessary building block for the foundations of mathematical cognition? A straightforward model to test the causal role visual experience plays in the development of numerical abilities is to study people born without sight. In this review we will demonstrate that congenitally blind people can develop numerical abilities that equal or even surpass those of sighted individuals, despite representing numbers using a qualitatively different representational format. We will also show that numerical thinking in blind people maps onto regions typically involved in visuo-spatial processing in the sighted, highlighting how intrinsic computational biases may constrain the reorganization of numerical networks in case of early visual deprivation. More generally, we will illustrate how the study of arithmetic abilities in congenitally blind people represents a compelling model to understand how sensory experience scaffolds the development of higher-level cognitive representations.

Take it of your shoulders: Providing scaffolds leads to better performance on mathematical word problems in secondary school children with developmental coordination disorder

BACKGROUND

Many children with developmental coordination disorder (DCD) have mathematical problems which are more pronounced for mathematical skills that also require executive functions. Although empirical evidence is missing, math and special education need teachers of children with DCD report difficulties with mathematical word problem solving that can be remediated by providing the children with scaffolds cueing the intermediate steps.

AIMS

This study aims to find empirical evidence for the effectivity of such additional support. In addition, we want to investigate whether the difficulties are due to inefficient arithmetic or executive functioning skills.

METHODS AND PROCEDURES

A DCD and a control group solved word problems with and without scaffolds and conducted a series of tasks measuring calculation and executive skills.

OUTCOMES AND RESULTS

Performance improves when scaffolds are presented to children with DCD. Children with DCD and control children differ on executive functioning tasks but perform similarly on arithmetic tests.

CONCLUSIONS AND IMPLICATIONS

Providing scaffolds for word problem solving is effective in children with DCD. Scaffolds possibly reduce the required cognitive load, making the problem solvable for DCD children that have reduced executive functioning skills.

Subitizing and counting impairments in children with developmental coordination disorder

Developmental coordination disorder (DCD) interferes with academic achievement and daily life, and is associated with persistent academic difficulties, in particular within mathematical learning. In the present study, we aimed to study numerical cognition using an approach that taps very basic numerical processes such as subitizing and counting abilities in DCD. We used a counting task and a subitizing task in forty 7-10 years-old children with or without DCD. In both tasks, children were presented with arrays of one to eight dots and asked to name aloud the number of dots as accurately and quickly as possible. In the subitizing task, dots were presented during 250 ms whereas in the counting task they stayed on the screen until the participants gave a verbal response. The results showed that children with DCD were less accurate and slower in the two enumeration tasks (with and without a time limit), providing evidence that DCD impairs both counting and subitizing. These impairments might have a deleterious impact on the ability to improve the acuity of the Approximate Number System through counting, and thus could play a role in the underachievement of children with DCD in mathematics.

Putting a Finger on Numerical Development - Reviewing the Contributions of Kindergarten Finger Gnosis and Fine Motor Skills to Numerical Abilities

The well-documented association between fingers and numbers is not only based on the observation that most children use their fingers for counting and initial calculation, but also on extensive behavioral and neuro-functional evidence. In this article, we critically review developmental studies evaluating the association between finger sensorimotor skills (i.e., finger gnosis and fine motor skills) and numerical abilities. In sum, reviewed studies were found to provide evidential value and indicated that both finger gnosis and fine motor skills predict measures of counting, number system knowledge, number magnitude processing, and calculation ability. Therefore, specific and unique contributions of both finger gnosis and fine motor skills to the development of numerical skills seem to be substantiated. Through critical consideration of the reviewed evidence, we suggest that the association of finger gnosis and fine motor skills with numerical abilities may emerge from a combination of functional and redeployment mechanisms, in which the early use of finger-based numerical strategies during childhood might be the developmental process by which number representations become intertwined with the finger sensorimotor system, which carries an innate predisposition for said association to unfold. Further research is nonetheless necessary to clarify the causal mechanisms underlying this association.

Executive function in children with and without developmental coordination disorder: A comparative study

BACKGROUND

Children with motor impairments also show poor performance in some executive functions' components. However, there is no consensus on which specific executive subdomain is more impacted.

AIM

The objective of this study was to compare executive functions in children with developmental coordination disorder (DCD), at risk for DCD (r-DCD), and in typically developing (TD) children.

METHODS AND PROCEDURES

A sample of 397 children was assessed using the MABC-2. Two groups of children were identified; DCD (n = 63) and at r-DCD (n = 31). A third matched group of children with TD (n = 63) was formed. The MABC-2 checklist and the WASI tests were used as screening tools. Measures of executive function including verbal and nonverbal tasks for working memory, inhibitory control, and cognitive flexibility were tested. Multivariate analysis of variance followed by analyses of variance and Bonferroni tests were used to verify group effects on executive functions.

RESULTS

A significant group effects were found for Working Memory, Λ = .78, F(4, 360) = 10.12, p ≤ .001, η_p² = .12; Inhibitory Control, Λ = .59, F(16, 294) = 5.48, p ≤ .001, η_p² = .23; and Cognitive Flexibility and Inhibitory Control, Λ = .60, F(22, 288) = 3.74, p ≤ .001, η_p² = .22, with moderate effect sizes. The DCD group showed lower scores compared with the TD group on the visuospatial and verbal working memory; inhibitory control and in tasks of cognitive flexibility; the r-DCD group showed lower scores compared with the TD group for visuospatial working memory and for cognitive flexibility.

CONCLUSIONS AND IMPLICATIONS

Poor performance in several measures of executive functions in children with DCD emphasized the need of motor/executive task-specific interventions. Furthermore, children at r-DCD showed low scores in several executive functions; therefore, preventive services should also be provided for this subclinical group.

The synergistic effect of poor motor coordination, gender and age on self-concept in children: A longitudinal analysis

BACKGROUND

Self-concept is a critical psychosocial outcome in childhood that is shaped by many factors. Gender, motor coordination and age have been identified as three important contributors.

AIM

The present study examined whether poor motor coordination (i.e., being classified as at risk for Developmental Coordination Disorder [rDCD]), gender and age have a synergistic effect on domains of self-concept and self-worth in children.

METHODS

Data were derived from the Physical Health and Activity Study Team longitudinal open cohort project. Children enrolled in grade 4 (M_age = 9.88 ± 0.35) at baseline (n = 1978) completed the Self-Perception Profile for Children 7 times over 4 years to evaluate their competence across multiple domains. The Bruininks-Oseretsky Test of Motor Proficiency - Short Form was completed once to evaluate children's motor coordination. Participants scoring ≤15th percentile were classified as rDCD.

RESULTS

A significant 3-way interaction between rDCD, gender and age was observed for athletic ability, physical appearance and academic competence, but not social competence, behavioural conduct or global self-worth. Findings revealed developmental trajectories for self-perceptions of athletic ability, physical appearance, and academic competence were lowest among rDCD girls. Boys classified as rDCD also demonstrated lower athletic, academic and physical self-perceptions in comparison to typically developing children.

CONCLUSIONS

Age intensifies disparities in self held athletic, physical and academic perceptions attributable to differences in gender and rDCD status, however, differences in these domains appear to be independent of children's overall views of themselves.

The interplay between non-symbolic number and its continuous visual properties revisited: Effects of mixing trials of different types

In the last few years, the existence of a pure number sense has been challenged. Recent studies suggest that numerosity processing is influenced not only by the number of elements in a display but also by continuous magnitudes, such as the size of the elements. The aim of our study was to replicate and extend the findings by Gebuis and Reynvoet, who systematically manipulated different continuous magnitudes either congruently or incongruently with discrete numerosity. We were particularly interested in finding the same pattern of congruency effects and assess its stability and robustness as this pattern indicates a complex influence of continuous magnitudes on numerosity judgements. We did so by showing stimuli of different conditions either in separate blocks or mixed together while participants solved a dot comparison task. Our results are in line with the notion that discrete number and continuous magnitudes are integrated in numerosity judgements by means of a weighing process. Moreover, our findings suggest that this integration is modified by the mode of presentation (blocked vs. mixed).

International clinical practice recommendations on the definition, diagnosis, assessment, intervention, and psychosocial aspects of developmental coordination disorder

AIM

These international clinical practice recommendations (CPR) for developmental coordination disorder (DCD), initiated by the European Academy of Childhood Disability (EACD), aim to address key questions on the definition, diagnosis, assessment, intervention, and psychosocial aspects of DCD relevant for clinical practice.

METHOD

Key questions in five areas were considered through literature reviews and formal expert consensus. For recommendations based on evidence, literature searches on 'mechanisms', 'assessment', and 'intervention' were updated since the last recommendations in 2012. New searches were conducted for 'psychosocial issues' and 'adolescents/adults'. Evidence was rated according to the Oxford Centre for Evidence-Based Medicine (level of evidence [LOE] 1-4) and transferred into recommendations. For recommendations based on formal consensus, two meetings of an international, multidisciplinary expert panel were conducted with a further five Delphi rounds to develop good clinical practice (GCP) recommendations.

RESULTS

Thirty-five recommendations were made. Eight were based on the evidence from literature reviews (three on 'assessment', five on 'intervention'). Twenty-two were updated from the 2012 recommendations. New recommendations relate to diagnosis and assessment (two GCPs) and psychosocial issues (three GCPs). Additionally, one new recommendation (LOE) reflects active video games as adjuncts to more traditional activity-oriented and participation-oriented interventions, and two new recommendations (one GCP, one LOE) were made for adolescents and adults with DCD.

INTERPRETATION

The CPR-DCD is a comprehensive overview of DCD and current understanding based on research evidence and expert consensus. It reflects the state of the art for clinicians and scientists of varied disciplines. The international CPR-DCD may serve as a basis for national guidelines.

WHAT THIS PAPER ADDS

Updated international clinical practice guidelines on developmental coordination disorder (DCD). Refined and extended recommendations on clinical assessment and intervention for DCD. A critical synopsis of current research on mechanisms of DCD. A critical synopsis of psychosocial issues in DCD, with implications for clinical practice. The first international recommendations to consider adolescents and adults with DCD.

Prevalence of suspected developmental coordination disorder and associated factors in Spanish classrooms

BACKGROUND

Developmental Coordination Disorder (DCD) is a multifactorial, neurodevelopmental motor disorder that severely affects the activities of a child's daily life and classroom performance. The aim of this study was to determine the prevalence of suspected DCD in a sample of Spanish schoolchildren and its association with socio-demographic factors.

METHODS

We conducted a cross-sectional study including a random sample of 460 children attending mainstream schools in northwest Spain in 2017. A Developmental Coordination Disorder Questionnaire-European Spanish was used to evaluate suspected DCD prevalence. We performed multivariate logistic and linear regression analysis to determine the socio-demographic variables associated with suspected DCD and problematic motor coordination performance.

RESULTS

The prevalence of suspected DCD was 12.2%. According to the multivariate analysis, DCD symptoms were significantly associated with males (OR = 3.0), ages above 10 years old (OR = 5.0) and low participation in out-of-school physical activities (OR = 2.3). Preterm birth children were twice as likely to show suspected DCD, although this association was not statistically significant (OR = 2.1).

CONCLUSIONS

A high percentage of Spanish schoolchildren are at risk for developing DCD. There is a strong connection between suspected DCD and socio-demographic factors. Protocols aimed to detect DCD and intervention programmes in classrooms designed to promote motor coordination skills need to take these factors into consideration.

Individual differences in basic numerical skills: The role of executive functions and motor skills

The aim of the current study was to explore individual differences in basic numerical skills in a normative sample of 151 kindergarteners (mean age = 6.45 years). Whereas previous research claims a substantial link between executive functions and basic numerical skills, motor abilities have been put forward to explain variance in numerical skills. Regarding the current study, these two assumptions have been combined, revealing interesting results. Namely, executive functions (inhibition, switching, and visuospatial working memory) were found to relate to symbolic numerical skills, and motor skills (gross and fine motor skills) showed a significant correlation to nonsymbolic numerical skills. Suggesting that motor skills and executive functions are associated with basic numerical skills could lead to potential avenues for interventions in certain disorders or disabilities such as nonverbal learning disability, developmental dyscalculia, and developmental coordination disorder.

Comparing Numerical Comparison Tasks: A Meta-Analysis of the Variability of the Weber Fraction Relative to the Generation Algorithm

Since more than 15 years, researchers have been expressing their interest in evaluating the Approximate Number System (ANS) and its potential influence on cognitive skills involving number processing, such as arithmetic. Although many studies reported significant and predictive relations between ANS and arithmetic abilities, there has recently been an increasing amount of published data that failed to replicate such relationship. Inconsistencies lead many researchers to question the validity of the assessment of the ANS itself. In the current meta-analysis of over 68 experimental studies published between 2004 and 2017, we show that the mean value of the Weber fraction (w), the minimal amount of change in magnitude to detect a difference, is very heterogeneous across the literature. Within young adults, w might range from < 10 to more than 60, which is critical for its validity for research and diagnostic purposes. We illustrate here the concern that different methods controlling for non-numerical dimensions lead to substantially variable performance. Nevertheless, studies that referred to the exact same method (e.g., Panamath) showed high consistency among them, which is reassuring. We are thus encouraging researchers only to compare what is comparable and to avoid considering the Weber fraction as an abstract parameter independent from the context. Eventually, we observed that all reported correlation coefficients between the value of w and general accuracy were very high. Such result calls into question the relevance of computing and reporting at all the Weber fraction. We are thus in disfavor of the systematic use of the Weber fraction, to discourage any temptation to compare given data to some values of w reported from different tasks and generation algorithms.

Cognitive predictors of sequential motor impairments in children with dyslexia and/or attention deficit/hyperactivity disorder

This study examined cognitive predictors of sequential motor skills in 215 children with dyslexia and/or attention deficit/hyperactivity disorder (ADHD). Visual working memory and math fluency abilities contributed significantly to performance of sequential motor abilities in children with dyslexia (N = 67), ADHD (N = 66) and those with a comorbid diagnosis (N = 82), generally without differentiation between groups. In addition, primary diagnostic features of each disorder, such as reading and inattention, did not contribute to the variance in motor skill performance of these children. The results support a unifying framework of motor impairment in children with neurodevelopmental disorders such as dyslexia and ADHD.

Numbers and functional lateralization: A visual half-field and dichotic listening study in proficient bilinguals

Potential links between language and numbers and the laterality of symbolic number representations in the brain are still debated. Furthermore, reports on bilingual individuals indicate that the language-number interrelationships might be quite complex. Therefore, we carried out a visual half-field (VHF) and dichotic listening (DL) study with action words and different forms of symbolic numbers used as stimuli to test the laterality of word and number processing in single-, dual-language and mixed -task and language- contexts. Experiment 1 (VHF) showed a significant right visual field/left hemispheric advantage in response accuracy for action word, as compared to any form of symbolic number processing. Experiment 2 (DL) revealed a substantially reversed effect - a significant right ear/left hemisphere advantage for arithmetic operations as compared to action word processing, and in response times in single- and dual-language contexts for number vs. action words. All these effects were language independent. Notably, for within-task response accuracy compared across modalities significant differences were found in all studied contexts. Thus, our results go counter to findings showing that action-relevant concepts and words, as well as number words are represented/processed primarily in the left hemisphere. Instead, we found that in the auditory context, following substantial engagement of working memory (here: by arithmetic operations), there is a subsequent functional reorganization of processing single stimuli, whether verbs or numbers. This reorganization - their weakened laterality - at least for response accuracy is not exclusive to processing of numbers, but the number of items to be processed. For response times, except for unpredictable tasks in mixed contexts, the "number problem" is more apparent. These outcomes are highly relevant to difficulties that simultaneous translators encounter when dealing with lengthy auditory material in which single items such as number words (and possibly other types of key words) need to be emphasized. Our results may also shed a new light on the "mathematical savant problem".

Neural Signature of DCD: A Critical Review of MRI Neuroimaging Studies

The most common neurodevelopmental disorders (e.g., developmental dyslexia (DD), autism, attention-deficit hyperactivity disorder (ADHD)) have been the subject of numerous neuroimaging studies, leading to certain brain regions being identified as neural correlates of these conditions, referring to a neural signature of disorders. Developmental coordination disorder (DCD), however, remains one of the least understood and studied neurodevelopmental disorders. Given the acknowledged link between motor difficulties and brain features, it is surprising that so few research studies have systematically explored the brains of children with DCD. The aim of the present review was to ascertain whether it is currently possible to identify a neural signature for DCD, based on the 14 magnetic resonance imaging neuroimaging studies that have been conducted in DCD to date. Our results indicate that several brain areas are unquestionably linked to DCD: cerebellum, basal ganglia, parietal lobe, and parts of the frontal lobe (medial orbitofrontal cortex and dorsolateral prefrontal cortex). However, research has been too sparse and studies have suffered from several limitations that constitute a serious obstacle to address the question of a well-established neural signature for DCD.

An Extension of the Procedural Deficit Hypothesis from Developmental Language Disorders to Mathematical Disability

Mathematical disability (MD) is a neurodevelopmental disorder affecting math abilities. Here, we propose a new explanatory account of MD, the procedural deficit hypothesis (PDH), which may further our understanding of the disorder. According to the PDH of MD, abnormalities of brain structures subserving the procedural memory system can lead to difficulties with math skills learned in this system, as well as problems with other functions that depend on these brain structures. This brain-based account is motivated in part by the high comorbidity between MD and language disorders such as dyslexia that may be explained by the PDH, and in part by the likelihood that learning automatized math skills should depend on procedural memory. Here, we first lay out the PDH of MD, and present specific predictions. We then examine the existing literature for each prediction, while pointing out weaknesses and gaps to be addressed by future research. Although we do not claim that the PDH is likely to fully explain MD, we do suggest that the hypothesis could have substantial explanatory power, and that it provides a useful theoretical framework that may advance our understanding of the disorder.

Examining the cognitive profile of children with Developmental Coordination Disorder

BACKGROUND

While primarily a motor disorder, research considering the cognitive abilities in children with Developmental Coordination Disorder (DCD) is limited; even though these children often struggle academically.

AIMS

The present study aimed to characterise the IQ profile of children with and without DCD, and to identify whether children with DCD exhibit specific cognitive weaknesses.

METHODS AND PROCEDURES

104 children participated in the study. Fifty-two children (mean age, 9 years) with a diagnosis of DCD were matched to 52 typically-developing children by age and gender. Cognitive ability was assessed using the Wechsler Intelligence Scale for Children (WISC-IV).

OUTCOMES AND RESULTS

Children with DCD performed poorer than their peers on processing speed and working memory measures. Individual analyses revealed varied performance in the DCD group across all cognitive indices, despite displaying Full-Scale IQs in the typical range. Discriminant function analyses show processing speed and working memory performance predicted only 23% of between-group variability.

CONCLUSIONS

Children with DCD present with a heterogeneous cognitive profile, lending support to individual case analyses in research and when designing educational assistance plans. The motorically-demanding nature of the WISC-IV processing speed tasks raises specific concerns about using this index of the IQ assessment in this population. Research and practical implications are raised.

Numerical abilities of school-age children with Developmental Coordination Disorder (DCD): A behavioral and eye-tracking study

Developmental Coordination Disorder (DCD) is a disorder of motor coordination which interferes with academic achievement. Difficulties in mathematics have been reported. Performance in the number line task is very sensitive to atypical development of numerical cognition. We used a position-to-number task in which twenty 7-to-10years old children with DCD and 20 age-matched typically developing (TD) children had to estimate the number that corresponded to a hatch mark placed on a 0-100 number line. Eye movements were recorded. Children with DCD were less accurate and slower to respond than their peers. However, they were able to map numbers onto space linearly and used anchoring strategies as control. We suggest that the shift to a linear trend reflects the ability of DCD children to use efficient strategies to solve the task despite a possibly more imprecise underlying numerical acuity.

From “sense of number” to “sense of magnitude”: The role of continuous magnitudes in numerical cognition

In this review, we are pitting two theories against each other: the more accepted theory, the number sense theory, suggesting that a sense of number is innate and non-symbolic numerosity is being processed independently of continuous magnitudes (e.g., size, area, and density); and the newly emerging theory suggesting that (1) both numerosities and continuous magnitudes are processed holistically when comparing numerosities and (2) a sense of number might not be innate. In the first part of this review, we discuss the number sense theory. Against this background, we demonstrate how the natural correlation between numerosities and continuous magnitudes makes it nearly impossible to study non-symbolic numerosity processing in isolation from continuous magnitudes, and therefore, the results of behavioral and imaging studies with infants, adults, and animals can be explained, at least in part, by relying on continuous magnitudes. In the second part, we explain the sense of magnitude theory and review studies that directly demonstrate that continuous magnitudes are more automatic and basic than numerosities. Finally, we present outstanding questions. Our conclusion is that there is not enough convincing evidence to support the number sense theory anymore. Therefore, we encourage researchers not to assume that number sense is simply innate, but to put this hypothesis to the test and consider whether such an assumption is even testable in the light of the correlation of numerosity and continuous magnitudes.

Numerosity but not texture-density discrimination correlates with math ability in children

Considerable recent work suggests that mathematical abilities in children correlate with the ability to estimate numerosity. Does math correlate only with numerosity estimation, or also with other similar tasks? We measured discrimination thresholds of school-age (6- to 12.5-years-old) children in 3 tasks: numerosity of patterns of relatively sparse, segregatable items (24 dots); numerosity of very dense textured patterns (250 dots); and discrimination of direction of motion. Thresholds in all tasks improved with age, but at different rates, implying the action of different mechanisms: In particular, in young children, thresholds were lower for sparse than textured patterns (the opposite of adults), suggesting earlier maturation of numerosity mechanisms. Importantly, numerosity thresholds for sparse stimuli correlated strongly with math skills, even after controlling for the influence of age, gender and nonverbal IQ. However, neither motion-direction discrimination nor numerosity discrimination of texture patterns showed a significant correlation with math abilities. These results provide further evidence that numerosity and texture-density are perceived by independent neural mechanisms, which develop at different rates; and importantly, only numerosity mechanisms are related to math. As developmental dyscalculia is characterized by a profound deficit in discriminating numerosity, it is fundamental to understand the mechanism behind the discrimination. (PsycINFO Database Record

Developmental coordination disorder: core sensori-motor deficits, neurobiology and etiology

Among developmental disorders, DCD is one of the least studied and less understood one (Bishop, 2010). This review summarizes the current understanding of developmental coordination disorder in neuropsychology with a focus mainly on high level sensorimotor impairments, its etiology and its neural bases. We summarize these core deficits in the framework of an influent motor control model (Blakemore et al., 2002). DCD has several environmental risk factors which probably interplay with genetic factors but those have not been sufficiently identified. High-level sensori-motor deficits are probably multifactorial in DCD and involve predictive coding deficits as well as weaknesses in perceptual and sensory integration. At the brain level, DCD is associated with impaired structure and functions within the motor network. Throughout the review we highlight exciting new findings as well as potential future lines of research to provide a more comprehensive understanding of this disorder.