Working memory, processing speed, and set-shifting in children with developmental coordination disorder and attention-deficit-hyperactivity disorder

It has been suggested that the high levels of comorbidity between attention-deficit-hyperactivity disorder (ADHD) and developmental coordination disorder (DCD) may be attributed to a common underlying neurocognitive mechanism. This study assessed whether children with DCD and ADHD share deficits on tasks measuring working memory, set-shifting, and processing speed. A total of 195 children aged between 6 years 6 months and 14 years 1 month (mean 10y 4mo [SD 2y 2mo]) were included in this study. A control group (59 males, 79 females), a DCD group (12 males, six females), an ADHD-predominantly inattentive group (16 males, four females), and an ADHD-combined group (15 males, four females), were tested on three executive functioning tasks. Children with DCD were significantly slower on all tasks, supporting past evidence of a timing deficit in these children. With few exceptions, children with ADHD did not perform more poorly than control children. These findings demonstrate the importance of identifying children with motor deficits when examining tasks involving a timing component.     

Neurocase,Volume 18, Guest reviewers

Abstract

In adults, moving an object using precision grip involves anticipatory adjustment of grip force for fluctuations in inertial load force. These adjustments suggest that motion planning is based on an internal model of the effect or system and the environment. In the current study, we evaluate the coordination of grip force with load force in a child with developmental coordination disorder (DCD) and a matched, normally developing, control child. The children completed five tasks: (i) lifting an object; (ii) moving an object upwards; (iii) moving an object downwards; (iv) holding an object subject to unpredictable perturbation; (v) a time production (tapping) task. A number of differences were observed between the children. In particular, compared to the control, the child with DCD showed an earlier rise in grip force when making both upward and downward movements. We discuss this result in relation to the greater variability in explicit timing and longer reflex delays observed in the child with DCD. We conclude that this paradigm offers insight into the motion planning difficulties seen in DCD, providing a useful new methodology for the investigation of the observed coordination difficulties.     

Head–torso–hand coordination in children with and without developmental coordination disorder

Aim This study investigated the nature of coordination and control problems in children with developmental coordination disorder (DCD). Method Seven adults (two males, five females, age range 20–28y; mean 23y, SD 2y 8mo) and eight children with DCD (six males, two females, age range 7–9y; mean 8y, SD 8mo), and 10 without DCD (seven males, three females, age range 7–9y; mean 8y, SD 7mo) sat in a swivel chair and looked at or pointed to targets. Optoelectronic apparatus recorded head, torso, and hand movements, and the spatial and temporal characteristics of the movements were computed. Results Head movement times were longer (p<0.05) in children with DCD than in the comparison group, even in the looking task, suggesting that these children experience problems at the lowest level of coordination (the coupling of synergistic muscle groups within a single degree of freedom). Increasing the task demands with the pointing condition affected the performance of children with DCD to a much greater extent than the other groups, most noticeably in key feedforward kinematic landmarks. Temporal coordination data indicated that all three groups attempted to produce similar movement patterns to each other, but that the children with DCD were much less successful than age‐matched children in the comparison group. Interpretation Children with DCD have difficulty coordinating and controlling single degree‐of‐freedom movements; this problem makes more complex tasks disproportionately difficult for them. Quantitative analysis of kinematics provides key insights into the nature of the problems faced by children with DCD.     

Association between visual perceptual deficits and motor deficits in children with developmental coordination disorder

This study explored the relation between a motor-free visual perceptual deficit, different visual-motor integration deficits, and different motor skills in children with developmental coordination disorder (DCD). Thirty-six children (22 males), aged 9 or 10 years, with DCD and a control group (n=36), matched for age and sex, were assessed with the Movement Assessment Battery for Children (MABC), a ball-catching test, a jumping test, a timed response task to a visual moving stimulus, and the Beery-Buktenica Developmental Test of Visual-Motor Integration, incorporating copying, visual discrimination, and tracing tasks. Children with DCD performed significantly worse than the control group on all measures. The visual discrimination task did not correlate significantly with any of the motor tasks. The visual timing task correlated significantly with the ball-catching test in the DCD group. The copying test was significantly correlated with the MABC in the DCD group. The association between visual-perceptual deficits and motor tasks was shown to be task specific.     

A dyspraxic deficit in specific language impairment and developmental coordination disorder? Evidence from hand and arm movements

The extent to which children with either specific language impairment (SLI) or developmental coordination disorder (DCD) could be considered dyspraxic was examined using three tasks involving either familiar, or unfamiliar actions. SLI is diagnosed in children who fail to develop language in the normal fashion for no apparent reason, while the DCD diagnosis is applied to a child who experiences problems with movement in the absence of other difficulties. Seventy-two children aged between 5 and 13 years participated, falling into one of four groups: (1) children with specific language impairment (SLI), (2) children with developmental coordination disorder (DCD), (3) age-matched control children, and (4) younger control children. The performance of the clinical groups resembled that of younger normally developing children. Children with SLI, DCD, and the younger controls showed significant difficulty on the task requiring the production of familiar, but not unfamiliar postures. The deficit observed in the SLI group is particularly striking because it was seen both in those with and those without recognized motor difficulties.     

Does relative body fat influence the Movement ABC-2 assessment in children with and without developmental coordination disorder?

Developmental coordination disorder (DCD) is a condition that results in an impairment of gross and/or fine motor coordination. Compromised motor coordination contributes to lower levels of physical activity, which is associated with elevated body fat. The impact of elevated body fat on motor coordination diagnostic assessments in children with DCD has not been established. The purpose of this study was to determine if relative body fat influences performance on the Movement Assessment Battery for Children, 2nd Edition (MABC-2) test items in children with and without DCD. A nested case–control, design was conducted within the Physical Health Activity Study Team longitudinal cohort study. The MABC-2 was used to assess motor coordination to categorize cases and matched controls. Relative body fat was assessed using whole body air displacement plethysmography. Relative body fat was negatively associated with the MABC-2 “balance” subcategory after adjusting for physical activity and DCD status. Relative body fat did not influence the subcategories of “manual dexterity” or “aiming and catching”. Item analysis of the three balance tasks indicated that relative body fat significantly influences both “2-board balance” and “zig-zag hopping”, but not “walking heel-toe backwards”. Children with higher levels of relative body fat do not perform as well on the MABC-2, regardless of whether the have DCD or not. Dynamic balance test items are most negatively influenced by body fat. Health practitioners and researchers should be aware that body fat can influence results when interpreting MABC-2 test scores.     

Children at risk for developmental coordination disorder: judgement of changes in action capabilities

In three separate manipulations, a group of children at risk for developmental coordination disorder (DCD; five males, seven females; mean age 11y 6mo [SD 6.8mo]who were at or below the 15^th centile on the Movement ABC) and a group of typically developing children (TDC; seven males, five females; mean age 11y 3mo [SD 6.8mo]) judged the limit of their standing horizontal reach (HR_max) under two conditions in which actual HR_max differed. The manipulations were: (1) one-hand versus two-hand reach; and (2) standard versus short effective foot-length; and (3) rigid versus compliant support surface. For the foot-length and support surface manipulations (but not for the hand manipulation), children correctly judged that their actual HR_max differed in the two conditions ( p <.05). On all three manipulations, TDC made significantly larger adjustments in their judgements than did children at risk for DCD ( p <0.05). The TDC group adjusted their judgements in the appropriate direction on all three manipulations, whereas the DCD group adjusted in the appropriate direction for the foot-length manipulation only. The results suggest that children at risk for DCD are less adept at detecting changes in the limits of their action capabilities.     

Postural responses to a suprapostural visual task among children with and without developmental coordination disorder

We sought to determine the effects of varying the perceptual demands of a suprapostural visual task on the postural activity of children with developmental coordination disorder (DCD), and typically developing children (TDC). Sixty-four (32 per group) children aged between 9 and 10 years participated. In a within-participants design, each child performed a signal detection task at two levels of difficulty, low (LD) and high difficulty (HD). During performance of the signal detection tasks we recorded positional variability of the head and torso using a magnetic tracking system. We found that task difficulty had a greater effect on task performance among the TDC group than among children with DCD. Overall positional variability was greater the DCD group than in the TDC group. In the TDC group, positional variability was reduced during performance of the HD task, relative to sway during performance of the LD task. In the DCD group, positional variability was greater during performance of the HD task than during performance of the LD task. In children, DCD may reduce the strength of functional integration of postural activity with the demands of suprapostural visual tasks.     

Emergence and stability of interlimb coordination patterns in children with developmental coordination disorder

The purpose of this study was to investigate the emergence and stability of coordination patterns in children with developmental coordination disorder (DCD) when performing a rhythmic interlimb coordination task on rigid (floor) and elastic (mini-trampoline) surfaces. Twelve typically developing (TD) children and 12 children with DCD were required to clap while jumping under different conditions: in a chosen pattern – Free; when the feet touched the surface – Clapping-surface; when the body reached the maximum jumping height – Clapping-jump; and when the feet touched the surface and the body reached the maximum jumping height – Clapping-both. The results showed that the coordination pattern of children with DCD was more variable in the Free, Clapping-surface, and Clapping-jumping conditions and more variable on the mini-trampoline than on the floor under the Free condition when compared with the TD children. Clapping-jumping was more difficult to perform than Clapping-surface for both groups. These findings suggest that the children with DCD were less capable of rhythmically coordinating the jumping-clapping task because they used a type of exploratory strategy regarding the physical properties of the surfaces, whereas the TD children used a type of adaptive strategy displaying behavior that was more consistent across the tasks/environmental demands.     

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

At school, children with Developmental Coordination Disorder (DCD) struggle with mathematics. However, little attention has been paid to their numerical cognition abilities. The goal of this study was to better understand the cognitive basis for mathematical difficulties in children with DCD.Twenty 7-to-10 years-old children with DCD were compared to twenty age—matched typically developing children using dot and digit comparison tasks to assess symbolic and nonsymbolic number processing and in a task of single digits additions.Results showed that children with DCD had lower performance in nonsymbolic and symbolic number comparison tasks than typically developing children. They were also slower to solve simple addition problems. Moreover, correlational analyses showed that children with DCD who experienced greater impairments in the nonsymbolic task also performed more poorly in the symbolic tasks.These findings suggest that DCD impairs both nonsymbolic and symbolic number processing. A systematic assessment of numerical cognition in children with DCD could provide a more comprehensive picture of their deficits and help in proposing specific remediation.     

Intact procedural motor sequence learning in developmental coordination disorder

The purpose of the present study was to explore the possibility of a procedural learning deficit among children with developmental coordination disorder (DCD). We tested 34 children aged 6–12 years with and without DCD using the serial reaction time task, in which the standard keyboard was replaced by a touch screen in order to minimize the impact of perceptuomotor coordination difficulties that characterize this disorder. The results showed that children with DCD succeed as well as control children at the procedural sequence learning task. These findings challenge the hypothesis that a procedural learning impairment underlies the difficulties of DCD children in acquiring and automatizing daily activities. We suggest that the previously reported impairment of children with DCD on the serial reaction time task is not due to a sequence learning deficit per se, but rather due to methodological factors such as the response mode used in these studies.     

Motor and cognitive performance differences between children with and without developmental coordination disorder (DCD)

The current study adopts the PASS theory of information processing to investigate the probable differences in specific motor and cognitive abilities between children with and without developmental coordination disorder (DCD). Participants were 108 5- and 6-year-old preschoolers (54 children with DCD and 54 children without DCD). The Movement Assessment Battery for Children assessed motor function. Running speed and agility were measured using the Bruininks-Oseretsky Test of Motor Proficiency. Finally, the Planning, Attention and Simultaneous Scales from the Das-Naglieri Cognitive Assessment System evaluated cognitive ability. Children with DCD differed significantly from those without DCD performing at a lower level on all motor and cognitive tasks. A correlation analysis revealed significant relationships between cognitive processes and motor skills. Simultaneous cognitive processing and manual dexterity were significantly correlated for both groups. Furthermore, a significant relationship was revealed between planning cognitive processing and balance for the non-DCD group. Thus, early assessment might identify specific cognitive-motor difficulties. Furthermore, early intervention might prevent some of the developmental comorbidities in the academic and everyday lives of children with movement difficulties.     

The integrity of visual-proprioceptive mapping in cerebral palsy.

Existing data on the ability of normal children to make intra-modal and cross-modal judgements about limb position are reviewed. A pattern of results emerges which suggests that although young children have difficulty with proprioceptive judgements, their performance is significantly enhanced if the task involves matching vision against proprioception. Some preliminary findings with cerebral palsied children suggest that this advantage may sometimes be lost. It is suggested, however, that the tasks used in previous studies do not allow the precise appraisal of this ability. This study examined intra- and cross-modal judgements in eight normal adults and eight severely cerebral palsied adolescents. In addition to the usual measures of spatial accuracy, joint angle measurements were recorded which allow some appraisal of the information strategy used for respective tasks. The results suggest that the cerebral palsied students had specific problems with mapping between vision and proprioception. This is discussed from a perspective of whether such mapping requires adaptive behaviour within a stable explorative environment, which is disrupted in cases of severe cerebral palsy.     

Characterization of motor control in handwriting difficulties in children with or without developmental coordination disorder

Aim The purpose of this study was to characterize handwriting deficits in children with developmental coordination disorder (DCD) using computerized movement analyses. Method Seventy‐two children (40 females, 32 males; mean age 7y, SD 7mo; range 6y 2mo to 7y 11mo) with handwriting deficits (33 with DCD, 39 without DCD); and 22 age‐ and sex‐matched children without handwriting deficits were asked to perform handwriting tasks on a digital tablet for the collection of kinematic and kinetic data. Practice times required to achieve automation of movement when writing an unfamiliar character were used to assess the motor learning of handwriting. The children were asked to copy three simple and three complex characters, and the velocity and axial pen force used for corresponding strokes were compared. Results The attainment of automated handwriting was markedly slower in children with handwriting deficits and DCD, who used a faster stroke velocity to write simple characters (1.22 times those without handwriting deficits), but when writing complex characters, their stroke velocity and pen force were lower (0.85 and 0.89 times those without handwriting deficits, respectively). Interpretation By linking the results with neuromotor control theories, it was determined that children with DCD have difficulties performing the open‐loop and closed‐loop movements required for fluent handwriting.     

A comparison of motor imagery performance in children with spastic hemiplegia and developmental coordination disorder

Individuals with hemiplegia have difficulty planning movements, which may stem from deficits in motor imagery ability. We explored motor imagery ability in three groups of 21 children, aged 8-12 years: children with hemiplegia; children with developmental coordination disorder (DCD); and a comparison group. They completed two tasks requiring laterality judgments of body parts--hand and whole-body rotation. Accuracy in both was reduced for the motor-impaired groups, and response time was atypical for the whole-body task. This suggests that motor imagery deficits exist in children with hemiplegia and DCD, supporting previous findings that planning deficits in hemiplegia may result from deficits in motor imagery.     

Mathematical problems in children with developmental coordination disorder

Developmental coordination disorder (DCD) is a heterogeneous disorder, which is often co-morbid with learning disabilities. However, mathematical problems have rarely been studied in DCD. The aim of this study was to investigate the mathematical problems in children with various degrees of motor problems. Specifically, this study explored if the development of mathematical skills in children with DCD is delayed or deficient. Children with DCD performed significantly worse for number fact retrieval and procedural calculation in comparison with age-matched control children. Moreover, children with mild DCD differed significantly from children with severe DCD on both number fact retrieval and procedural calculation. In addition, we found a developmental delay of 1 year for number fact retrieval in children with mild DCD and a developmental delay of 2 years in children with severe DCD. No evidence for a mathematical deficit was found. Diagnostic implications are discussed.     

Motor and gestural performance in children with autism spectrum disorders, developmental coordination disorder, and/or attention deficit hyperactivity disorder.

Motor and gestural skills of children with autism spectrum disorders (ASD), developmental coordination disorder (DCD), and/or attention deficit hyperactivity disorder (ADHD) were investigated. A total of 49 children with ASD, 46 children with DCD, 38 children with DCD+ADHD, 27 children with ADHD, and 78 typically developing control children participated. Motor skills were assessed with the Bruininks-Oseretsky Test of Motor Proficiency Short Form, and gestural skills were assessed using a test that required children to produce meaningful gestures to command and imitation. Children with ASD, DCD, and DCD+ADHD were significantly impaired on motor coordination skills; however, only children with ASD showed a generalized impairment in gestural performance. Examination of types of gestural errors revealed that children with ASD made significantly more incorrect action and orientation errors to command, and significantly more orientation and distortion errors to imitation than children with DCD, DCD+ADHD, ADHD, and typically developing control children. These findings suggest that gestural impairments displayed by the children with ASD were not solely attributable to deficits in motor coordination skills.     

Evaluation of the Japanese version of the Developmental Coordination Disorder Questionnaire as a screening tool for clumsiness of Japanese children

Developmental Coordination Disorder (DCD) is characterized by clumsiness and coordination difficulties. DCD interferes with academic performance and participation in physical activities and psychosocial functions, such as self-esteem, cognition, or emotion, from childhood through adolescence to adulthood. DCD is a common pediatric condition and its prevalence is estimated to be 6% worldwide. Although English questionnaires are available, there is no questionnaire to identify DCD in Japan, and therefore, no information on its prevalence is available. Recently, we developed the Japanese version of the Developmental Coordination Disorder Questionnaire (DCDQ-J). The purpose of this study was to describe the applicability of the DCDQ-J for use with a community-based population of children in Japan and to investigate the relationships between coordination and attention-deficit hyperactivity disorder (ADHD) tendencies or intelligence. The DCDQ-J was completed by 6330 parents or guardians of children and adolescents. We employed the ADHD-rating scale and determined the intelligence quotient (IQ) of the children. Two-way analysis of variance showed that the scores linearly increased as the children's grades advanced in 2 subscales, namely, control during movement and fine motor. In contrast, non-linear changes were found in the scores of the general coordination subscale. The total scores of the DCDQ-J and ADHD-RS were significantly correlated, but no relationship between DCDQ-J scores and IQ was found. The DCDQ-J is expected to be a useful screening tool to identify and assess motor coordination difficulties of children in Japan and enable cross-cultural comparisons.     

The effectiveness of exercise intervention on inhibitory control in children with developmental coordination disorder: Using a visuospatial attention paradigm as a model

Children with developmental coordination disorder (DCD) have been demonstrated to show a deficit of inhibitory control in volitional shifts of attention. The aim of this study was to use ecological intervention to investigate the efficacy of table-tennis training on treating both problems with attentional networks and motor disorder in children with DCD. Forty-three children aged 9–10 years old were screened using the Movement Assessment Battery for Children and divided into DCD (n = 27) and typically developing (TD, n = 16) groups. Children with DCD were then quasi-randomly assigned to either a DCD-training group who underwent a ten-week table-tennis training program with a frequency of 3 times a week or a DCD non-training group. Before and after training, the capacity of inhibitory control was examined with the endogenous Posner paradigm task for DCD and TD groups. Table-tennis training resulted in significant improvement of cognitive and motor functions for the children with DCD. The study demonstrated that exercise intervention employed within the school setting can benefit the inhibitory control and motor performance in children with DCD. However, future research efforts should continue to clarify whether the performance gains could be maintained over time.     

Motor coordination and health-related physical fitness of children with developmental coordination disorder: a three-year follow-up study

Health-related physical fitness is an important risk factor of cardiovascular disease. While previous studies have identified children with developmental coordination disorder (DCD) to be less physically fit than typically developing (TD) peers, there is limited longitudinal research in this area. This study was undertaken to evaluate concomitant changes in motor coordination and health-related physical fitness of Taiwanese children with and without DCD over a three-year period. The Movement Assessment Battery for Children (Movement ABC) test was used to evaluate motor coordination, while health-related physical fitness included several core components: (1) body mass index (BMI), (2) sit and reach forward, (3) long jump, (4) sit-ups, and (5) 800-m run. Both the Movement ABC and fitness tests were implemented once each a year for three years. Twenty-five children with DCD and 25 TD children, matched by age and gender participated in this study. The TD group showed significant long-term changes in BMI and long jump while the DCD group showed significant increases in BMI values and decreases in flexibility, measured by the sit and reach task. In general, children with DCD performed worse on the items of flexibility, muscle strength and muscle endurance after the first year. Compared to age- and gender-matched norms, children with DCD not only were less physically fit, but showed a significant long-term decline in flexibility and abdominal or core strength (sit-ups). In years two and three, there was a significant negative correlation between poor fitness and motor coordination. Based on the results of this longitudinal study, greater attention should be paid to monitoring and improving physical fitness of children with DCD to prevent further health-related problems while intervention.