Mild impairments of motor imagery skills in children with DCD

It has been hypothesized that the underlying mechanism of clumsy motor behaviour in children with Developmental Coordination Disorder (DCD) is caused by a deficit in the internal modelling for motor control. An internal modelling deficit can be shown on a behavioural level by a task that requires motor imagery. Motor imagery skills are suggested to be related to anticipatory action planning, but motor imagery and action planning have not been tested within the same child. In the present study, action planning and motor imagery skills were assessed in 82 children between 7 and 12 years of age. Twenty-one of these children met the criteria for DCD, which was assessed by the McCarron Assessment of Neuromuscular Development and 56 of these children were used in the control group. Motor imagery was tested by a mental rotation task of hands that were shown from a back and palm point of view. The results show that motor imagery is affected in children with DCD but only in conditions with complex task constraints (i.e., rotation of hand stimuli presented in palm view). These results provide partial support for the internal modelling deficit hypothesis. We were not able to elicit motor planning deficits in this group, however, and argue that more complex planning tasks may be needed to identify such deficits.     

Motor imagery ability in children with congenital hemiplegia: effect of lesion side and functional level

In addition to motor execution problems, children with hemiplegia have motor planning deficits, which may stem from poor motor imagery ability. This study aimed to provide a greater understanding of motor imagery ability in children with hemiplegia using the hand rotation task. Three groups of children, aged 8-12 years, participated: right hemiplegia (R-HEMI; N = 21), left hemiplegia (L-HEMI; N = 19) and comparisons (N = 21). All groups conformed to biomechanical limitations of the task, supporting the use of motor imagery, and all showed the expected response-time trade-off for angle. The general slowing of responses in the HEMI groups did not reach significance compared to their peers. The L-HEMI group were less accurate than the comparison group while the R-HEMI group were more variable in their performance. These results appeared to be linked to functional level. Using the Vineland Adaptive Behavior Composite, children were classified as low or normal functioning - of the seven classified as low function, six were in the L-HEMI group. Accuracy was lower in the low function subgroup, but this failed to reach significance with an adjusted critical value. However, there was a strong correlation between function level and mean accuracy. This indicates that motor imagery performance may be more closely linked to function level than to the neural hemisphere that has been damaged in cases of congenital hemiplegia. Function level may be linked to the site or extent of neural damage or the level of cortical reorganisation experienced and more attention should be paid to neural factors in future research.     

Tool length influences reach distance estimation via motor imagery in children with developmental coordination disorder

Purpose: Children with developmental coordination disorder (DCD) often have difficulties with planning and generating a precise visuospatial representation of intended actions and using motor imagery to mentally represent motor behavior. Here, we aimed to extend the investigation of motor imagery in children with DCD by exploring its use with an estimation of reach paradigm that combines action representation and extension of space with tools. Method: Two groups of 18 children with DCD and typically developing (TD) matched controls were tested with an estimation of reach paradigm using a 20-cm (Experiment 1) and 40-cm (Experiment 2) tool. Conditions involved estimations via motor imagery with their arm, tool, and a switch-block (SB) involving an abrupt change of space with an “extension” from arm to tool and a “retraction” from tool to arm. Results: No significant group differences were found with the 20-cm tool; however, with the 40-cm implement, children with DCD were significantly less accurate than their TD counterparts. Conclusions: Compared to TD children, those with DCD have more difficulty estimating reach distances using the longer of two tool lengths: 40 cm compared to 20 cm. This finding may be related to differences in quality of motor imagery and in the ability to create an effective internal model for action in this context. Furthermore, our results suggest that tool length may present an additional action processing constraint on children with DCD. Additional studies are necessary to determine other constraints that children with DCD have when integrating tool use with spatial judgments for reach actions, as well as provide rehabilitation insights that involve motor imagery combined with tool use.     

Compromised motor control in children with DCD: A deficit in the internal model?—A systematic review

A viable hypothesis to explain the compromised motor ability of children with Developmental Coordination Disorder (DCD) suggests a fundamental deficit in their ability to utilize internal models for motor control. Dysfunction in this mode of control is thought to compromise their motor learning capabilities. The aim of this systematic review is to examine the available evidence for the internal modeling deficit (IMD) hypothesis. A systematic review using five databases identified 48 relevant articles. These studies were categorized according to the effector system involved in the evaluation of motor control and were evaluated for methodological quality. In most papers, DSM-IV-TR criteria for the classification of DCD were not completely fulfilled and possible attentional problems not accounted for. Results showed compromised control of overt and covert eye movements, dynamic postural control, manual control for tasks that vary in complexity, and for motor imagery of manual and whole-body postures. Importantly, this review shows support for general hypothesis that deficits of predictive control manifest in DCD across effector systems.     

Internal representation of movement in children with developmental coordination disorder: a mental rotation task

Recent studies show that children with developmental coordination disorder (DCD) have difficulties in generating an accurate visuospatial representation of an intended action, which are shown by deficits in motor imagery. This study sought to test this hypothesis further using a mental rotation paradigm. It was predicted that children with DCD would not conform to the typical pattern of responding when required to imagine movement of their limbs. Participants included 16 children with DCD and 18 control children; mean age for the DCD group was 10 years 4 months, and for controls 10 years. The task required children to judge the handedness of single-hand images that were presented at angles between 0 degrees and 180 degrees at 45 degrees intervals in either direction. Results were broadly consistent with the hypothesis above. Responses of the control children conformed to the typical pattern of mental rotation: a moderate trade-off between response time and angle of rotation. The response pattern for the DCD group was less typical, with a small trade-off function. Response accuracy did not differ between groups. It was suggested that children with DCD, unlike controls, do not automatically enlist motor imagery when performing mental rotation, but rely on an alternative object-based strategy that preserves speed and accuracy. This occurs because these children manifest a reduced ability to make imagined transformations from an egocentric or first-person perspective.     

Motor imagery and action observation for predictive control in developmental coordination disorder

In 2019, international clinical practice recommendations on the definition, diagnosis, assessment, intervention, and psychosocial aspects of developmental coordination disorder (DCD) were published. Informing our understanding of mechanisms, recent systematic reviews have shown that children with DCD have difficulties with the predictive control of movements, including aspects of motor planning, which is expressed as the internal modeling deficit hypothesis. This motor control deficit is most evident when the spatial and temporal demands of a task increase. An increasing number of empirical studies suggest that motor planning problems can be remediated through training based on one or a combination of motor imagery and action observation. In this review, we show evidence of motor planning problems in children with DCD and show that task demands or complexity affects its appearance. Implications of these findings are treatments based on motor imagery and action observation to remediate motor planning issues. The article concludes with recommendations for future research.     

Motor imagery training enhances motor skill in children with DCD: A replication study

BackgroundChildren with impaired motor coordination (or DCD) have difficulty using motor imagery. We have suggested that this difficulty is explained by the internal modeling deficit (IMD) hypothesis of DCD. Our previous training study lent support for this hypothesis by showing that a computerized imagery training protocol (involving action observation, and mental- and overt-rehearsal) was equally effective to perceptual-motor therapy (PMT) in promoting motor skill acquisition.AimsThe study presented here was designed to replicate and extend this finding, targeting a select group of children with moderate-to-severe DCD.Methods and ProceduresAll 36 children with DCD who participated were referred to the study and scored below the 10th percentile for their age on the Movement Assessment Battery for Children (MABC). Using a randomized control trial, the referred children were assigned randomly to one of three groups using a blocked procedure: imagery training, perceptual-motor training (PMT), and wait-list control. Motor proficiency was measured using the MABC, pre and post-training. Individual training consisted of 60-min sessions, conducted once a week for 5 weeks.ResultsResults showed that the imagery protocol was equally effective as PMT in promoting motor skill acquisition, with moderate-to-large effect sizes. Individual differences showed that the majority of children in the two intervention groups improved their motor performance significantly.ConclusionsOverall, these results further support the use of motor imagery protocols in the treatment of DCD, and tentative support for the IMD hypothesis. Developmental and dose issues in the implementation of imagery-based intervention are discussed.     

Understanding performance deficits in developmental coordination disorder: a meta‐analysis of recent research

Aim Developmental coordination disorder (DCD) is a significant disorder of childhood, characterized by core difficulties in learning fine and/or gross motor skills, and the attendant psychosocial problems. The aim of the meta‐analysis presented here (the first on DCD since 1998) was to summarize trends in the literature over the past 14 years and to identify and describe the main motor control and cognitive deficits that best discriminate children with DCD from those without. Method A systematic review of the literature published between January 1997 and August 2011 was conducted. All available journal papers reporting a comparison between a group of children with DCD and a group of typically developing children on behavioural measures were included. Results One hundred and twenty‐nine studies yielded 1785 effect sizes based on a total of 2797 children with DCD and 3407 typically developing children. Across all outcome measures, a moderate to large effect size was found, suggesting a generalized performance deficit in children with DCD. The pattern of deficits suggested several areas of pronounced difficulty, including internal (forward) modelling, rhythmic coordination, executive function, gait and postural control, catching and interceptive action, and aspects of sensoriperceptual function. Interpretation The results suggest that the predictive control of action may be a fundamental disruption in DCD, along with the ability to develop stable coordination patterns. Implications for theory development and intervention are discussed.     

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.     

Motor imagery training in hemiplegic cerebral palsy: a potentially useful therapeutic tool for rehabilitation

Converging evidence indicates that motor deficits in cerebral palsy (CP) are related not only to problems with execution, but also to impaired motor planning. Current rehabilitation mainly focuses on alleviating compromised motor execution. Motor imagery is a promising method of training the more 'cognitive' aspects of motor behaviour, and may, therefore, be effective in facilitating motor planning in patients with CP. In this review first we present the specific motor planning problems in CP followed by a discussion of motor imagery and its use in clinical practice. Second, we present the steps to be taken before motor imagery can be used for rehabilitation of upper limb functioning in CP. Motor imagery training has been shown to be a useful addition to existing rehabilitation protocols for poststroke rehabilitation. No such study has been conducted in CP. The age at which children can reliably use motor imagery, as well as the specific way in which motor imagery training needs to be implemented, must be researched before motor imagery training can be employed in children with CP. Based on the positive results for poststroke rehabilitation, and in light of the motor problems in CP, motor imagery training may be a valuable additional tool for rehabilitation in CP.     

Motor impairments screened by the Movement Assessment Battery for Children-2 are related to the visual-perceptual deficits in children with Developmental Coordination Disorder

This study was to examine to what extent the motor deficits of children with Developmental Coordination Disorder (DCD) verified by the Movement Assessment Battery for Children-2 (MABC-2) are linked to their visual-perceptual abilities. Seventeen children with DCD and seventeen typically developing children (TD) aged 5–10 years screened from a total of 250 children were recruited. The assessments included MABC-2, traditional test of visual perceptual skills (TVPS-R), and computerized test for sequential coupling of eye and hand as well as motion coherence. The results indicated that children with DCD scored lower than TD in MABC-2, and their total scores were highly correlated with manual dexterity component scores. DCD group also showed poor visual-perceptual abilities in various aspects. The visual discrimination and visual sequential memory from the TVPS-R, the sequential coupling of eye and hand, and the motion coherence demonstrated a moderate or strong correlation with the MABC-2 in the DCD rather than the TD group. It was concluded that the motor problems screened by MABC-2 were significantly related to the visual-perceptual deficits of children with DCD. MABC-2 is suggested to be a prescreening tool to identify the visual-perceptual related motor deficits.     

Reduced motor imagery efficiency is associated with online control difficulties in children with probable developmental coordination disorder

Recent evidence indicates that the ability to correct reaching movements in response to unexpected target changes (i.e., online control) is reduced in children with developmental coordination disorder (DCD). Recent computational modeling of human reaching suggests that these inefficiencies may result from difficulties generating and/or monitoring internal representations of movement. This study was the first to test this putative relationship empirically. We did so by investigating the degree to which the capacity to correct reaching mid-flight could be predicted by motor imagery (MI) proficiency in a sample of children with probable DCD (pDCD). Thirty-four children aged 8 to 12 years (17 children with pDCD and 17 age-matched controls) completed the hand rotation task, a well-validated measure of MI, and a double-step reaching task (DSRT), a protocol commonly adopted to infer one's capacity for correcting reaching online. As per previous research, children with pDCD demonstrated inefficiencies in their ability to generate internal action representations and correct their reaching online, demonstrated by inefficient hand rotation performance and slower correction to the reach trajectory following unexpected target perturbation during the DSRT compared to age-matched controls. Critically, hierarchical moderating regression demonstrated that even after general reaching ability was controlled for, MI efficiency was a significant predictor of reaching correction efficiency, a relationship that was constant across groups. Ours is the first study to provide direct pilot evidence in support of the view that a decreased capacity for online control of reaching typical of DCD may be associated with inefficiencies generating and/or using internal representations of action.     

Obesity and motor coordination ability in Taiwanese children with and without developmental coordination disorder

The purpose of this study was to investigate the associations between obesity and motor coordination ability in Taiwanese children with and without developmental coordination disorder (DCD). 2029 children (1078 boys, 951 girls) aged nine to ten years were chosen randomly from 14 elementary schools across Taiwan. We used bioelectrical impedance analysis to measure percentage of body fat (PBF) and the Movement Assessment Battery for Children test (MABC test) to evaluate the motor coordination ability. Using cut-off points based on PBF from past studies, boys and girls were divided into obese, overweight and normal-weight groups, respectively. In boys, total impairment scores and scores on balance subtest in the MABC were significantly higher in the obese and overweight groups when compared against the normal-weight group. Girls in the obese and the overweight groups had higher balance impairment scores than those of the normal-weight group. Among boys, the prevalence of obesity was highest in the DCD group, when compared to the borderline DCD and TD boys. A higher percentage of DCD girls were overweight and obese than TD girls. Obesity may be associated with poor motor coordination ability among boys and girls, and particularly in relation to balance ability. Children with DCD may have a higher risk to be overweight or obese in Taiwan.     

Reduced relative volume in motor and attention regions in developmental coordination disorder: A voxel-based morphometry study

Background and objectivesDevelopmental coordination disorder (DCD) is a prevalent childhood movement disorder, impacting the ability to perform movement skills at an age appropriate level. Although differences in grey matter (GM) volumes have been found in related developmental disorders, no such evidence has been linked with DCD to date. This cross-sectional study assessed structural brain differences in children with and without DCD.MethodsHigh-resolution structural images were acquired from 44 children aged 7.8–12 years, including 22 children with DCD (≤16th percentile on MABC-2; no ADHD/ASD), and 22 typically developing controls (≥20th percentile on MABC-2). Structural voxel-based morphology analysis was performed to determine group differences in focal GM volumes.ResultsChildren with DCD were found to have significant, large, right lateralised reductions in grey matter volume in the medial and middle frontal, and superior frontal gyri compared to controls. The addition of motor proficiency as a covariate explained the between-group GM volume differences, suggesting that GM volumes in motor regions are reflective of the level of motor proficiency. A positive correlation between motor proficiency and relative GM volume was also identified in the left posterior cingulate and precuneus.ConclusionsGM volume reductions in premotor frontal regions may underlie the motor difficulties characteristic of DCD. It is possible that intervention approaches targeting motor planning, attention, and executive functioning processes associated with the regions of reduced GM volume may result in functional improvements in children with DCD.     

Assessment of body composition using whole body air-displacement plethysmography in children with and without developmental coordination disorder

Developmental coordination disorder (DCD) is a neuro-developmental disorder characterized by poor fine and/or gross motor coordination. Children with DCD are hypothesized to be at increased risk for overweight and obesity from inactivity due to their motor coordination problems. Although previous studies have found evidence to support this hypothesis, their reliance on field-based measures, most notably body mass index (BMI), to determine body composition is problematic. Moreover, there has been no research to date that has examined whether THERE ARE differences in lean tissue mass between children with and without coordination. Differences in muscle mass, the main component of lean tissue, may be a contributing factor to both coordination problems and the development of overweight and obesity, but has only been indirectly examined at this time. In this study, whole-body air displacement using a dual chamber plethysmograph was used to estimate fat mass, fat free mass and body fat in children with probable DCD (pDCD) and a group of typically developing children. Consistent with previous research using field-based assessments of relative body weight, the results show that children with pDCD have much higher body fat than their peers, and that this difference increases with the severity of observed motor coordination difficulties. There was no difference in lean tissue mass between groups. The demonstration of an association between pDCD and body fat using a more sensitive measure of body composition, and evidence showing a dose-response in this relationship, further supports the hypothesis that DCD may be a risk factor for obesity in children.     

A systematic review of mirror neuron system function in developmental coordination disorder: Imitation,motor imagery,and neuroimaging evidence

PURPOSEThe aim of this systematic review was to investigate the evidence of abnormal functioning of the mirror neuron system (MNS) in children and adults with developmental coordination disorder (DCD), through examination of imitation, motor imagery, and neuroimaging literature.METHODSThe following databases were comprehensively searched for relevant articles: CINAHL Plus, Embase, MEDLINE, PsycINFO, Pubmed, and Web of Science. Full-text articles of all potentially relevant citations were obtained and assessed for eligibility by two authors. Outcome measures of interest at a motor behaviour level were any measures of imitation or motor imagery proficiency and, at a neurological level, were any measures of neural activity in MNS brain regions. Due to differences in outcome measures between studies and the variables reported, a narrative review was undertaken to synthesise findings from the studies.RESULTSOverall, 31 articles met the inclusion criteria. Children and adults with DCD display deficits imitating meaningful and novel gestures and demonstrate different response patterns to controls when undertaking complex motor imagery tasks. Children with DCD present reduced activation and connectivity of frontal, parietal, and temporal MNS regions.CONCLUSIONSPreliminary evidence indicates some deficit in the functioning of the MNS at a motor behaviour and neurological level. As no published neuroimaging studies have been designed specifically to explore MNS function, these results must be interpreted with caution. Further research to explore the MNS hypothesis in greater detail, particularly from a neuroimaging perspective, has the potential to provide information on the underlying mechanisms of DCD, inform future research into the aetiology of this disorder, and inform intervention approaches.     

Unique deficit in embodied simulation in autism: An fMRI study comparing autism and developmental coordination disorder

A deficit in pre‐cognitively mirroring other people''s actions and experiences may be related to the social impairments observed in autism spectrum disorder (ASD). However, it is unclear whether such embodied simulation deficits are unique to ASD or instead are related to motor impairment, which is commonly comorbid with ASD. Here we aim to disentangle how, neurologically, motor impairments contribute to simulation deficits and identify unique neural signatures of ASD. We compare children with ASD (N = 30) to children with Developmental Coordination Disorder (DCD; N = 23) as well as a typically developing group (N = 33) during fMRI tasks in which children observe, imitate, and mentalize about other people''s actions. Results indicate a unique neural signature in ASD: during action observation, only the ASD group shows hypoactivity in a region important for simulation (inferior frontal gyrus, pars opercularis, IFGop). However, during a motor production task (imitation), the IFGop is hypoactive for both ASD and DCD groups. For all tasks, we find correlations across groups with motor ability, even after controlling for age, IQ, and social impairment. Conversely, across groups, mentalizing ability is correlated with activity in the dorsomedial prefrontal cortex when controlling for motor ability. These findings help identify the unique neurobiological basis of ASD for aspects of social processing. Furthermore, as no previous fMRI studies correlated brain activity with motor impairment in ASD, these findings help explain prior conflicting reports in these simulation networks.     

Statistically characterizing intra- and inter-individual variability in children with Developmental Coordination Disorder

Previous research investigating children with Developmental Coordination Disorder (DCD) has consistently reported increased intra- and inter-individual variability during motor skill performance. Statistically characterizing this variability is not only critical for the analysis and interpretation of behavioral data, but also may facilitate our understanding of the processes underlying DCD. Thus, the primary purpose of this research was to demonstrate the utility of a flexible statistical technique, a random coefficient model (RCM), that characterizes the increased intra- and inter-individual variability in children with and without DCD. We analyzed data from a sensorimotor adaptation task during which participants executed discrete aiming movements under conditions of rotated visual feedback. To highlight the advantages of this statistical approach, we contrasted the results from the RCM with those from a traditionally employed general linear model (GLM). The RCM revealed differences between the two groups of children that the GLM did not detect; and, characterized trajectories of change for each individual. The RCM provides researchers an opportunity to probe behavioral deficits at the individual level and may provide new insights into the behavioral heterogeneity in children with DCD.     

Attention deficits and clumsiness in Swedish 7-year-old children

A population study of 409 seven-year-old children in a middle-sized Swedish town was performed. All children were examined by the same doctor and evaluated by means of parent interview, motor examinations, and teacher reports on behaviour in the classroom. Follow-up was carried out 8 months later. The rate of severe problems in the fields of attention deficit-hyperactivity disorder (ADHD), developmental coordination disorder (DCD), and deficits in attention, motor control, and perception (DAMP) (the combination of ADHD and DCD) was 6.1%, with boys being affected more frequently than girls. There was considerable overlap between ADHD and DCD, with about half of each diagnostic group also meeting criteria for the other diagnosis. Attention deficits at diagnosis strongly predicted attention deficits at follow-up. If parents had noted attention deficits in the home setting, then teachers almost always independently agreed that there were similar problems in the classroom. However, the reverse did not always apply. Clumsiness also showed striking stability over time. The diagnosis of DAMP, particularly severe DAMP, had a stronger association with classroom dysfunction and with high Conners scores than did diagnoses of ADHD or DCD. It is concluded that DAMP may be a clinically valid diagnostic construct.     

Motor ability and weight status are determinants of out-of-school activity participation for children with developmental coordination disorder

According to the International Classification of Functioning, Disability and Health model endorsed by the World Health Organization, participation in everyday activities is integral to normal child development. However, little is known about the influence of motor ability and weight status on physical activity participation in children with developmental coordination disorder (DCD). This study aimed to (1) compare motor performance, weight status and pattern of out-of-school activity participation between children with DCD and those without; and (2) identify whether motor ability and weight status were determinants of participation patterns among children with DCD. We enrolled 81 children with DCD (boys, n = 63; girls, n = 18; mean age, 8.07 ± 1.5 years) and 67 typically developing children (boys, n = 48; girls, n = 19; mean age, 8.25 ± 1.6 years). Participation patterns (diversity, intensity, companionship, location, and enjoyment) were evaluated with the Children Assessment of Participation and Enjoyment. Motor ability was evaluated with the Movement Assessment Battery for Children, second edition (MABC-2). Other factors that may influence participation such as age, gender, and body weight were also recorded. Analysis of variance was used to compare outcome variables of the two groups, and significant determinants of activity participation were identified by multiple regression analysis. Children with DCD participated in fewer activities (i.e., limited participation diversity) and participated less frequently (i.e., limited participation intensity) than their typically developing peers; however, companionship, location of participation, and enjoyment level did not differ between the two groups. Children in the DCD group demonstrated significantly worse motor ability as assessed by the MABC-2. Further, a greater proportion of children in the DCD group were in the overweight/obese category compared with their typically developing peers. After accounting for the effects of age and gender, motor ability and weight category explained 7.6% and 5.0% of the variance in participation diversity, respectively, for children with DCD. Children with DCD showed less diverse and less intense out-of-school activity participation than typically developing children. Motor impairment and weight status were independently associated with the lower participation diversity. Interventions aiming at improving participation for children with DCD should target weight control and training in motor proficiency. Further study is needed to identify other factors that may hinder participation in this group of children.