A comparison of characteristics,developmental disorders and motor progression between children with and without developmental coordination disorder

Background and aimChildren with Developmental Coordination Disorder (DCD) have difficulty in the development of motor coordination and with learning new motor skills. Studies demonstrate that children with DCD differ in terms of the nature and severity of their motor difficulties, the incidence of co occurring conditions and family background. However, little is known whether these profiles may relate to motor progression over time. The aim of this study was to describe the profiles of children with and without DCD and track motor progression over time.MethodThe characteristics of thirty-four 7–14 year old children (M = 10.07, 85.3% boys) with and without DCD were compared and their motor progression monitored over a two academic years. DCD was identified using DSM5 criteria. The Movement Assessment Battery for Children-2 (MABC-2) was used to classify children as TD (≥25th percentile), having moderate motor coordination difficulties (6-16th percentile) or severe motor coordination difficulties (≤ 5th percentile). The Kaufman Brief Intelligence Test – 2 (KBIT-2) was used to measure full scale IQ. Parent questionnaires were used to gather information on socio economic status and co occurrence of other developmental disorders. We used ANOVA to assess whether there were differences in characteristics between the TD children, children with severe motor coordination difficulties and children with moderate motor coordination difficulties. Linear mixed effect modelling was used to estimate any change in motor performance over time and whether this differed between the three groups of children.ResultsChildren with severe motor coordination difficulties had distinct profiles in motor and non-motor domains, lower IQ and a greater likelihood of having associated characteristics of 2 or more developmental disorders. We found significant differences between the poor motor performance of the severe group compared to the other two groups. Longitudinal analyses revealed stable, persistent and lower motor competence for the severe group. The rate of change in motor proficiency for the typical and severe groups was similar. However, the group with moderate motor difficulties gained on average more points per week compared to the typical group and achieved motor scores in the typically developing range over time.ConclusionsThis is one of the first studies to compare the characteristics and rate of motor progression of children with and without DCD using different motor proficiency cut off scores. The children with severe motor coordination difficulties progressed at the same rate as typically developing peers but remained in the severe group over time, whereas the children with moderate motor coordination difficulties caught up to TDC. The results indicate that different intervention may be required according to the nature and severity of the characteristics in both the motor and non-motor domains of children with DCD.     

Impaired re-weighting of sensory feedback for maintenance of postural control in children with developmental coordination disorder

To further the understanding of postural control impairments seen in children with developmental coordination disorder (DCD) and the effect of these impairments on motor performance in these children, 30 children with and without DCD (mean age=9 years, 7 months +/- 1 year, 10 months) were administered the Movement Assessment Battery for Children (M-ABC), Wechsler Abbreviated Scale of Intelligence and the Sensory Organization Test. Analyses of covariance revealed that children with DCD had greater difficulty maintaining postural control when visual and somatosensory feedback were compromised in sensory conflict environments (p=.031). Group differences in postural control were independent of age. Additionally, no correlation was seen between motor performance on the M-ABC and postural control measures for the Sensory Organization Test. Our results demonstrate that impaired ability to utilize vestibular feedback while re-weighting somatosensory and visual feedback for orientation may be responsible, in part, for the postural control impairments observed in some children with DCD.     

Working memory, reading, and mathematical skills in children with developmental coordination disorder

The aim of the present study was investigate the relationship between working memory and reading and mathematical skills in 55 children diagnosed with developmental coordination disorder (DCD). The findings indicate a pervasive memory deficit in all memory measures. In particular, deficits observed in visuospatial short-term and working memory tasks were significantly worse than in the verbal short-term memory ones. On the basis of these deficits, the sample was divided into high and low visuospatial memory ability groups. The low visuospatial memory group performed significantly worse on the attainment measures compared to the high visuospatial memory group, even when the contribution of IQ was taken into account. When the sample was divided into high and low verbal working memory ability groups, verbal working memory skills made a unique contribution to attainment only when verbal IQ was taken into account, but not when performance IQ was statistically controlled. It is possible that the processing demands of the working memory tasks together with the active motor component reflected in the visuospatial memory tasks and performance IQ subtest both play a crucial role in learning in children with DCD.     

Developmental coordination disorder: associated problems in attention,learning, and psychosocial adjustment

This study investigated the problems of attention, learning and psychosocial adjustment evidenced by children with developmental coordination disorder (DCD). Forty-five children identified with DCD, 51 children identified as being suspect for DCD and 78 comparison children without motor problems on standardized tests of motor function participated in this study. Results revealed that both children with DCD and children suspect for DCD obtained significantly poorer scores on measures of attention and learning (reading, writing and spelling) than comparison children. Children with DCD and those suspect for DCD were also found to evidence a relatively high level of social problems and display a relatively high level of somatic complaints based on parent report. These findings indicate that all children with movement problems are at risk for problems in attention, learning and psychosocial adjustment. Assessment of children with movement problems, regardless of the degree or severity of these problems should examine a wide range of functions in addition to motor functioning. Such an approach, would assist in determining the types of intervention that would provide the most benefit to these children.     

Abnormalities of motor and praxis imagery in children with DCD

In an earlier study using the visually guided pointing task (VGPT) the authors showed that the timing of imagined movement sequences in children with developmental coordination disorder (DCD) does not conform to the conventional speed-for-accuracy trade-off (or Fitts' law [P.M. Fitts, Journal of Experimental Psychology 47 (1954) 381-391]) that occurs when the distance and accuracy requirements of movements are varied [P. Maruff, P.H. Wilson, M. Trebilcock, J. Currie, Neuropsychologia 37 (1999b) 1317-1324]. The present study sought to replicate this earlier finding and to examine (using a weight manipulation) whether this deficit was also attributable to inaccurate programming of relative force. The chronometry of real and imagined movements was investigated in a group of 20 children with DCD aged between 8 and 12 years and a group of controls matched on age and verbal IQ (VIQ). Movement duration was tested for real and imagined movements using the preferred hand, with the VGPT performed under two load conditions: with and without the addition of a weight attached to a pen. Group means of each subjects' mean movement duration were calculated and plotted against target width for each of the four conditions [Movement type (2) x Load (2)] and a logarithmic curve was fitted to the data points. In the control group, the speed-for-accuracy trade-off for both real and imagined performance conformed to Fitts' law under each load condition. In the DCD group only real movements conformed to Fitts' law. Moreover, the effect of load differed between groups--for real movements, movement duration did not differ between load and no-load conditions for either group, while for imagined movements, movement duration increased under the load condition for the control group only. These results replicate and extend the results of our earlier study. This pattern of performance suggests that children with DCD have an impairment in the ability to generate internal representations of volitional movements which may reflect an impaired ability to process efference copy signals. The ability to programme both relative force and timing appears to underly this difficulty. Results have implications for the use of (guided) motor imagery training in order to facilitate the development of motor skill in children with DCD.     

Differences in postural control and movement performance during goal directed reaching in children with developmental coordination disorder

Poor upper-limb coordination is a common difficulty for children with developmental coordination disorder (DCD). One hypothesis is that deviant muscle timing in proximal muscle groups results in poor postural and movement control. The relationship between muscle timing, arm motion and children's upper-limb coordination deficits has not previously been studied. The aim of this study was to investigate the relationship between functional difficulties with upper-limb motor skills and neuromuscular components of postural stability and coordination. Sixty-four children aged 8-10 years, 32 with DCD and 32 without DCD, participated in the study. The study investigated timing of muscle activity and resultant arm movement during a rapid, voluntary, goal-directed arm movement. Results showed that compared to children without DCD, children with DCD took significantly longer to respond to visual signals and longer to complete the goal-directed movement. Children with DCD also demonstrated altered activity in postural muscles. In particular, shoulder muscles, except for serratus anterior, and posterior trunk muscles demonstrated early activation. Further, anterior trunk muscles demonstrated delayed activation. In children with DCD, anticipatory function was not present in three of the four anterior trunk muscles. These differences support the hypothesis that in children with DCD, altered postural muscle activity may contribute to poor proximal stability and consequently poor arm movement control when performing goal-directed movement. These results have educational and functional implications for children at school and during activities of daily living and leisure activities and for clinicians assessing and treating children with DCD.     

Activities of daily living in children with developmental coordination disorder: dressing, personal hygiene, and eating skills

In order to understand how age, culture, and problems in motor coordination impact the performance of activities of daily living, we used focus groups and in-depth interviews with Australian and Canadian parents to examine activities of daily living of younger (5-7 years of age) and older (8-9 years of age) children with and without DCD. By comparison with their typically developing age group, children with DCD had more difficulty with dressing, personal hygiene, and eating skills. Difficulties with postural control and fine-motor skills were reported to contribute to poorer performance of activities of daily living. As expected, competence in the performance of activities of daily living improved in the older children with and without DCD and there were few differences in the performance of daily living tasks between typical children in Australia and Canada. Overall, the motor difficulties of children with DCD had a significant impact on performance of a wide range of daily activities.     

Comparison of motor praxis and performance in children with varying levels of developmental coordination disorder

The praxis test is a less well-documented method to determine functional manifestations of childhood dyspraxia. For this study, children aged 6–8 years were recruited as follows: 17 children with DCD, 18 at risk of DCD and 35 without obvious problems in motor coordination. The Movement Assessment Battery for Children (MABC-2) was used to measure motor performance and identify the motor incoordination. This study developed a battery of tests to assess limb praxis using a praxis imagery questionnaire, gesture representation, and questions about knowledge of object use. In the comparison of subtests within the praxis test, significant differences were observed across groups on the praxis imagery questionnaire and gesture representation tests but not on knowledge of object use. Similar results were observed in the correlation analyses, in which a weak relationship between MABC-2 and praxis tests was observed. The DCD group had lower scores on the praxis imagery questionnaire, whereas the group at risk of DCD had lower scores on most gesture production tests. Our study provides a better understanding of the nature of the childhood dyspraxia and sheds light on its effect on motor coordination to identify praxis tests with specific clinical meanings in children with movement disorders.     

Identifying play characteristics of pre-school children with developmental coordination disorder via parental questionnaires

Motor coordination deficits that characterize children with Developmental Coordination Disorder (DCD) affect their quality of participation. The aim of the current study was to identify play characteristics of young children with DCD, compared to those of children with typical development in three dimensions: activity and participation, environmental factors and children’s impairments.MethodSixty-four children, aged four to six years, participated. Thirty were diagnosed as having DCD; the remaining 34 children were age, gender and socioeconomic level matched controls with typical development. The children were evaluated by the M-ABC. In addition, their parents completed a demographic questionnaire, the Children’s Activity Scale for Parents (CHAS-P), the Children’s Leisure Assessment Scale for preschoolers (CLASS-Pre), and My Child’s Play Questionnaire (MCP).ResultsChildren with DCD performed significantly poorer in each of the four play activity and participation domains: variety, frequency, sociability, and preference (CLASS-Pre). Furthermore, their environmental characteristics were significantly different (MCP). They displayed significantly inferior performance (impairments) in interpersonal interaction and executive functioning during play, in comparison to controls (MCP). Moreover, the children’s motor and executive control as reflected in their daily function as well as their activities of daily living (ADL) performance level, contributed to the prediction of their global play participation.DiscussionThe results indicate that the use of both the CLASS-Pre and the MCP questionnaires enables the identification of unique play characteristics of pre-school children with DCD via parents’ reports. A better insight into these characteristics may contribute to theoretical knowledge and clinical practice to improve the children’s daily participation.     

Development of motor imagery ability in children with developmental coordination disorder – A goal-directed pointing task

Children with developmental coordination disorder (DCD) have difficulties with the predictive control of movements. This was shown in studies that target motor imagery and motor planning, and appears to become particularly evident with increases in task complexity. In this study, we used a complex mental chronometry paradigm to examine the development of motor imagery ability in children with DCD, using a longitudinal design. Thirty children were included in the DCD group (aged 6–11 years) and age- and gender-matched to 30 controls. The DCD group had a Movement Assessment Battery for Children-2 score ≤16th percentile and the control group ≥25th percentile. Results of this study showed that children with DCD indeed had a significantly lower correlation between executed and imagined movements. Importantly, the increase in the correlation and linear fit during subsequent measurements was comparable for the DCD and control group. Together, these findings suggest a delayed developmental onset of motor imagery ability in DCD, but a similar rate of development over time compared to the control group. Based on these results, it seems likely that explicit motor imagery instructions can be used to improve predictive control in children with DCD.     

What Does the DAP:IQ Measure?: Drawing Comparisons between Drawing Performance and Developmental Assessments

Human figure drawing tasks such as the Draw-a-Person test have long been used to assess intelligence (F. Goodenough, 1926). The authors investigate the skills tapped by drawing and the risk factors associated with poor drawing. Self-portraits of 345 preschool children were scored by raters trained in using the Draw-a-Person Intellectual Ability test (DAP:IQ) rubric (C. R. Reynolds & J. A. Hickman, 2004). Analyses of children's fine motor, gross motor, social, cognitive, and language skills revealed that only fine motor skill was an independent predictor of DAP:IQ scores. Being a boy and having a low birth weight were associated with lower DAP:IQ scores. These findings suggest that although the DAP:IQ may not be a valid measure of cognitive ability, it may be a useful screening tool for fine motor disturbances in at-risk children, such as boys who were born at low birth weights. Furthermore, researchers who use human figure drawing tasks to measure intelligence should measure fine motor skill in addition to intelligence.     

Neuroimaging and Occupational Therapy: Bridging the Gap to Advance Rehabilitation in Developmental Coordination Disorder

Developmental coordination disorder (DCD) is a neurodevelopmental disorder characterized by poor motor skills that interfere with a child's ability to perform everyday activities. Little is known about the neural mechanisms that implicate DCD, making it difficult to understand why children with DCD struggle to learn motor skills and selecting the best intervention to optimize function. Neuroimaging studies that utilize magnetic resonance imaging techniques have the capacity to play a critical role in helping to guide clinicians to optimize functional outcomes of children with DCD using evidence-based rehabilitation interventions. The authors' goal is to describe how neuroimaging research can be applied to occupational therapy and rehabilitation sciences by highlighting projects that are at the forefront of the field and elucidate future directions.     

Timing and force control in boys with attention deficit hyperactivity disorder: subtype differences and the effect of comorbid developmental coordination disorder

This study examined the motor and performance outcomes of boys with subtypes of attention deficit hyperactivity disorder (ADHD) (DSM-IV, [American Psychiatric Association, Diagnostic and statistical manual of mental disorders, 4th ed., Washington, DC, 1994]). It also examined the differences between boys with a single diagnosis of ADHD versus those who have the dual categorisation of ADHD and developmental coordination disorder (DCD). The participants were 157 boys, aged 7.70-12.98 years recruited from a community sample. Parent report was used to classify 143 boys into either a comparison group or one of the three DSM-IV ADHD subtypes. Participants were given a battery of tests that included the Movement Assessment Battery for Children [Movement Assessment Battery for Children, Psychological Corporation/Harcourt Brace-Jovanovich, New York, 1992], the Wechsler Intelligence Scales for Children--Third Edition [Manual for the Wechsler Intelligence Scale for Children, Psychological Corporation, New York, 1992] and a finger tapping task targeting motor processing, preparation, and execution. Boys with subtypes that included inattentive symptomatology had significant difficulties with timing, force output and showed greater variability in motor outcomes. Boys with the comorbid condition (i.e., ADHD and DCD) had particular difficulty with force control. These outcomes identify a need for increased recognition of the clinical and research implications of the relationship between ADHD and motor dysfunction. This potentially impacts on assessment, intervention, theoretical modelling and the general interpretation of cognitive abilities research with children with ADHD.     

Developmental coordination disorder pertains to a deficit in perceptuo-motor synchronization independent of attentional capacities

We investigated from a dynamic pattern perspective to motor coordination whether the deficiency in motor coordination characterizing Developmental Coordination Disorder children pertains to a general disorder in synchronization leading to a lower stability of the performed coordination pattern, and the extent to which the trouble is linked to attentional capacities. Twenty-four DCD children without ADHD aged eight to thirteen and 60 control children were asked (1) to perform a Continuous Performance Test assessing sustained attention; (2) to flex one finger either in synchrony or in syncopation with a visual periodic signal whose frequency was increased stepwise, assessing synchronization abilities. For the attentional task, percentage of exact responses, number of errors and reaction time were recorded. For the synchronization task, we measured relative phase (i.e., the ratio between the stimulus and the response onset and the time separating two successive stimuli). DCD children were significantly more variable than controls in both conditions and the difficulty in synchronization was unrelated to attentional disorders (ANCOVA). These findings support the idea of a general synchronization disorder in DCD children underlying their poor motor coordination. Moreover, this synchronization disorder does not appear to be strictly dependent on the level of sustained attentional capacities.     

Attentional processes in young children with congenital visual impairment

The study investigated attentional processes of 32 preschool children with congenital visual impairment (VI). Children with profound visual impairment (PVI) and severe visual impairment (SVI) were compared to a group of typically developing sighted children in their ability to respond to adult directed attention in terms of establishing, maintaining, and shifting attention on toys. The measures of children's sensory‐motor understanding (SMU) and language ability were obtained using the Reynell‐Zinkin scales of mental development. The video‐recordings of these play‐based assessments were coded for three categories of behavioural responses (Establish, Maintain, and Shift). The three groups were matched on verbal comprehension (VC), but differed significantly in their SMU and their chronological age. The groups of children with PVI and SVI were found to be comparable in their ability to establish and maintain attention on objects. Despite a relatively good performance overall both groups scored significantly lower on those skills than children who were sighted. However, with regards to attention shifting, children with PVI showed significantly lower performance than both the children with SVI and the sighted children who were similar on this component. Ability to maintain and shift attention was significantly related to the cognitive ability of children with PVI; however the poorer attentional responses were not confined only to the children with low IQ. The results are discussed in relation to the role of vision, cognitive ability and executive function in attentional processes in children with congenital VI.     

Parameterization of movement execution in children with developmental coordination disorder

The Rhythmic Movement Test (RMT) evaluates temporal and amplitude parameterization and fluency of movement execution in a series of rhythmic arm movements under different sensory conditions. The RMT was used in combination with a jumping and a drawing task, to evaluate 36 children with Developmental Coordination Disorder (DCD) and a matched control group. RMT errors in space and in time were significantly larger for children with DCD. Omission of sensory information decreased the accuracy of movement parameterization in children with DCD more than in the control group, suggesting that children with DCD have more problems in building up an internal representation of the movement. Errors in time correlated significantly with the jumping and drawing task, while errors in space did not. Deficits of temporal movement parameterization might be one of the underlying causes of poor motor performance in some children with DCD.     

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.     

Development of motor imagery and anticipatory action planning in children with developmental coordination disorder – A longitudinal approach

Children with impaired motor coordination (or Development Coordination Disorder – DCD) have difficulty with the predictive control of movements, evidenced by cross-sectional studies that show impaired motor imagery and action planning abilities. What remains unclear is whether this deficit in predictive control reflects immaturity of the motor system (a developmental delay) or some deviation from normal development (a disorder). To advance this discussion the present study used a longitudinal design to examine the development of motor imagery and action planning in children with DCD. Thirty children were included in the DCD group (aged 6–11 years) and age- and gender-matched to 30 controls. The DCD group had a mABC-2 score ≤ 16th percentile, the control group > 20th percentile. Motor imagery was assessed with the hand rotation task, action planning with a test for end-state comfort. Children participated in three measurements, with one year in between measurements. Results showed that children with DCD were slower and less accurate than their typically developing peers in all subsequent years but were able to improve their motor imagery ability over time. Furthermore, children with DCD showed less planning for ESC at the start of the present study, but were able to catch up with their peers during two-year follow up. These results exemplify that improvement of motor imagery and action planning ability is possible in DCD, and they lend theoretical support to the use of new training techniques that focus on training motor imagery to improve motor skills in children with DCD.     

弱智儿童感知动作技能特点的实验研究

本研究以难易程度不同的两个打洞操作作业 ,对弱智儿童和正常儿童的感知 动作技能进行了多种参数的测查。结果发现 :两类儿童在理解操作要点、操作速度、操作动作协调性以及操作正确性等各个方面都有明显的差异。同时通过比较 ,对弱智儿童感知 动作技能的特点 ,从外部肢体动作方式和内部智力动作方式两方面进行了详细的分析 ,并在此基础上对弱智儿童的感知 动作技能的教育与训练提出了建议 ,这对弱智学校改革教学、提高教学质量具有重要意义。     

Tactile localization performance in children with developmental coordination disorder (DCD) corresponds to their motor skill and not their cognitive ability

When localizing touches to the hands, typically developing children and adults show a “crossed hands effect” whereby identifying which hand received a tactile stimulus is less accurate when the hands are crossed than uncrossed. This demonstrates the use of an external frame of reference for locating touches to one’s own body. Given that studies indicate that developmental vision plays a role in the emergence of external representations of touch, and reliance on vision for representing the body during action is atypical in developmental coordination disorder (DCD), we investigated external spatial representations of touch in children with DCD using the “crossed hands effect”. Nineteen children with DCD aged 7–11 years completed a tactile localization task in which posture (uncrossed, crossed) and view (hands seen, unseen) were varied systematically. Their performance was compared to that of 35 typically developing controls (19 of a similar age and cognitive ability, and 16 of a younger age but similar fine motor ability). Like controls, the DCD group exhibited a crossed hands effect, whilst their overall tactile localization performance was weaker than their peers of similar age and cognitive ability, but in line with younger controls of similar motor ability. For children with movement difficulties, these findings indicate tactile localization impairments in relation to age expectations, but apparently typical use of an external reference frame for localizing touch.