Functional performance of children with developmental coordination disorder at home and at school

This study investigated the functional performance of daily activities at home and at school in a population-based sample of children with different degrees of motor coordination impairment and competence. Sixteen children (seven males, nine females; mean age 8y, SD 9mo) with developmental coordination disorder (DCD), 25 with suspected DCD ([sDCD] 17 males, eight females; mean age 7y 6mo, SD 8mo), and 63 children without motor problems (39 males, 24 females; mean age 7y 9mo, SD 7mo) were recruited from public schools (Grades 1–3, age 6y 4mo–9y 10mo) using the Chinese version of the Developmental Coordination Disorder Questionnaire, the Movement Assessment Battery for Children, and the Bruininks-Oseretsky Test of Motor Proficiency. Functional performance was assessed using the Chinese versions of the Vineland Adaptive Behavior Scales and the School Function Assessment–Chinese version. The functional performance of children with DCD and sDCD was statistically significantly lower than those without DCD ( p's <0.05). χ² and logistic regression analyses showed significant differences among all groups in the proportion of children scoring at the 'inadequate' adaptive level of home performance ( p's <0.05). There were also significant differences among the groups in the proportion of children scoring below the cut-off in school performance ( p's <0.05). The findings show the pervasive impact of DCD on children's functional performance in daily activities at home and at school.     

Developmental delay of finger torque control in children with developmental coordination disorder

Aim We examined whether the behavioral impairments in finger torque control evident in children with developmental coordination disorder (DCD) follow a delayed or different developmental trajectory compared with their typically developing peers. Method Children with DCD (n=36; 18 males, 18 females; mean age 9y 7mo, SD 1y 8mo) and 36 typically developing children (15 males, 21 females; mean age 9y 7mo, SD 2y), between 6 years 10 months and 12 years 7 months of age were recruited from schools in Porto Alegre, Brazil. Particpants completed finger torque control and maximum finger torque production tasks. The inclusion criterion for children with DCD was a Movement Assessment Battery for Children score below the fifth centile. Group means and cross‐sectional age‐related landscapes of the two groups were compared. Results Children with DCD were more variable (p<0.001), less accurate (p=0.007), and less irregular (p<0.001), on average, in their finger torque control than their typically developing peers, despite producing nearly equivalent levels of maximum torque (p=0.49). Despite these mean differences, the cross‐sectional age‐related changes in torque control were similar in the two groups (all p>0.05). Interpretation The developmental trajectory of finger torque control in children with DCD, compared with typically developing children, is delayed. This suggests the behavioral deficits in finger torque control in children with DCD persist as a function of age, rather than progressing or resolving.     

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.     

Anticipatory postural adjustments in a bimanual load‐lifting task in children with developmental coordination disorder

Aim Postural control is a fundamental component of action in which deficits have been shown to contribute to motor difficulties in children with developmental coordination disorder (DCD). The purpose of this study was to examine anticipatory postural adjustments (APAs) in children with DCD in a bimanual load‐lifting task. Method Sixteen children with reported motor problems (two females, 14 males; mean age 9y; SD 2y) and 16 typically developing, age‐matched children (six females, 10 males; mean age 9y; SD 2y) took part in the study. The task required the children to maintain a stable elbow angle, despite imposed or voluntary unloading of the forearm. APAs were assessed using electromyography and kinematics analysis. Results Although children with DCD could compensate for the consequences of unloading, the results demonstrated that APAs were less efficient in children with DCD than in typically developing children. A positive and significant coefficient of regression between the flexor inhibition latency and the postural stabilization was only found in typically developing children. Interpretation The impaired fine‐tuning of the muscle contribution and the poor stabilization performances demonstrate poor predictive modelling in DCD.     

Motor coordination, empathy, and social behaviour in school-aged children

Children with motor coordination problems are known to have emotional difficulties and poor social skills. The current study investigated whether children with poor motor ability have poor emotion recognition skills, and whether these could be linked to problems in social behaviour. It was hypothesized that difficulties in empathic ability might be related to the poor visuo-spatial processing ability identified in children with developmental coordination disorder (as defined by the American Psychiatric Association). The relationship between motor coordination, emotion recognition, and social behaviour was examined in a sample of 234 children (113 males, 121 females; mean age 9y 7mo, [SD 1y 8mo] age range 6y 8mo to 12y 11mo). From this sample two groups of 39 children each (17 females, 22 males), one group with motor difficulties (mean age 9y 11mo [SD 2y], range 6y 11mo to 12y 11mo) and the other of control children (mean age 10y [SD ly 11mo], range 6y 11mo to 12y 11mo), matched for age and sex, were compared using a set of six emotion recognition scales that measured both verbal and perceptual aspects of empathic ability. Children with motor difficulties were found to perform more poorly on scales measuring the ability to recognize static and changing facial expressions of emotion. This difference remained even when visuo-spatial processing was controlled. When controlling for emotion recognition and visuo-spatial organization, a child's motor ability remained a significant predictor of social behaviour.     

Gross motor development in children adopted from orphanage settings

Aim This study sought to examine the effect of environmental enrichment on the motor skills of children adopted from orphanage settings. We investigated balance and bilateral coordination skills in 33 internationally adopted postinstitutionalized children (16 males, 17 females; age range 8y 5mo–15y 10mo; mean age 10y 9mo; SD 2y 2mo) and compared them with 34 non‐institutionalized children (21 males, 13 females; age range 8y 3mo–14y 10mo; mean age 11y 2mo; SD 2y 1mo) being raised in their birth families. Method The children were individually administered the balance and bilateral coordination subtests of the Bruininks–Oseretsky Test of Motor Proficiency in a research laboratory. Parents completed questionnaires about developmental history, family environment, and orphanage care. Results Postinstitutionalized children showed motor system delays compared with the non‐institutionalized comparison children (postinstitutionalized balance mean 9.44, SD 5.92, comparison children balance mean 14.12, SD 4.39; postinstitutionalized bilateral coordination mean 11.97, SD 5.43, comparison children mean 19.97, SD 3.97). The length of time that children remained institutionalized before adoption predicted balance delays (b=?1.57, t=?2.33, p=0.027) and the severity of caregiving deprivation the children experienced correlated with bilateral coordination (r=?0.44, p=0.013). Interpretation These findings suggest that institutionalized settings do not provide the early life experiences needed for the development of age‐level motor skills later in childhood and that simple environmental enrichment following adoption is not enough to remediate skills. Children who have experienced early institutional care may benefit from early identification and targeted intervention.     

Developmental coordination disorder,sex, and activity deficit over time: a longitudinal analysis of participation trajectories in children with and without coordination difficulties

Aim Children with developmental coordination disorder (DCD) are known to participate in active play less than typically developing children. However, it is not known whether the activity deficit between children with and without DCD widens or diminishes over time. Method Data were obtained from a large, prospective cohort study of children (baseline n=2278, total n=2470). Motor coordination was assessed for 2083 students using the short form of the Bruininks–Oseretsky Test of Motor Proficiency. Participation in organized and free‐play activities was assessed using a participation questionnaire on five occasions over 3 years. Mixed‐effects modelling was used to examine differences in participation over time between children with probable DCD (pDCD, n=111, 46 males, 65 females) and their typically developing peers (n=1972, 1016 males, 956 females). The mean age for the whole sample was 9 years 11 months (SD 5mo) at assessment 1, 10 years 5 months (SD 5mo) at assessment 2, 10 years 11 months (SD 5mo) at assessment 3, 11 years 4 months (SD 4mo) at assessment 4, and 11 years 11 months (SD 4mo) at assessment 5. Results Children with pDCD reported less participation in organized and free‐play activities than their typically developing peers, and these differences persisted over time. Among males, the gap in participation in free‐play activities between those with DCD and typically developing children diminished substantially over time; among females, it increased slightly. Interpretation DCD is associated with a persistent activity deficit in children. Its effect on participation appears to be particularly serious among females but may diminish with time among males.     

Developmental coordination disorder in children with attention-deficit-hyperactivity disorder and physical therapy intervention

Although physical therapy (PT) is effective in improving motor function in children with developmental coordination disorder (DCD), insufficient data are available on the impact of this intervention in children with combined attention-deficit-hyperactivity disorder (ADHD) and DCD. This prospective study aimed to establish the prevalence of DCD among a cohort of patients with ADHD, characterize the motor impairment, identify additional comorbidities, and determine the role of PT intervention on these patients. DCD was detected in 55.2% of 96 consecutive children with ADHD (81 males, 15 females), mostly among patients with the inattentive type (64.3% compared with 11% of those with the hyperactive/impulsive type, p<0.05). Mean age was 8 years 4 months (SD 2 y). Individuals with both ADHD and DCD more often had specific learning disabilities (p=0.05) and expressive language deficits (p=0.03) than children with ADHD only. Twenty-eight patients with ADHD and DCD randomly received either intensive group PT (group A, mean age 9 y 3 mo, SD 2 y 3 mo) or no intervention (group B, mean age 9 y 3 mo, SD 2 y 2 mo). PT significantly improved motor performance (assessed by the Movement Assessment Battery for Children; p=0.001). In conclusion, DCD is common in children with ADHD, particularly of the inattentive type. Patients with both ADHD and DCD are more likely to exhibit specific learning disabilities and phonological (pronunciation) deficits. Intensive PT intervention has a marked impact on the motor performance of these children.     

Stability of motor problems in young children with or at risk of autism spectrum disorders,ADHD, and or developmental coordination disorder

Aim The aim of this study was to investigate the stability of motor problems in a clinically referred sample of children with, or at risk of, autism spectrum disorders (ASDs), attention‐deficit–hyperactivity disorder (ADHD), and/or developmental coordination disorder (DCD). Method Participants were 49 children (39 males, 10 females; mean age 5y 6mo, SD 10mo) with various developmental problems, a Movement Assessment Battery for Children (M‐ABC) score on or below the 15th centile, and an IQ of 70 or more. Sixteen children were at risk of developing ADHD, 15 children had a diagnosis of, or were at risk of developing ASD, and 18 children had neither diagnosis. Children were reassessed 2 to 3 years later. Results At follow‐up (mean age 7y 11mo; SD 1y), the mean M‐ABC score was significantly increased, and in 22 children was no longer below the 15th centile. A general linear model to compare the difference in M‐ABC scores in the three groups of children demonstrated a significant difference between groups (p=0.013), with the age at the initial assessment as a significant covariate (p=0.052). The group of children with or at risk of ASD showed less improvement in motor performance. Interpretation Motor problems among preschool age children are not always stable, but appear to be so in most children with ASDs.     

Ball catching in children with developmental coordination disorder: control of degrees of freedom

This study investigated two-handed catching in eight children (four males, four females) aged 7 to 8 years (mean 7y 4mo [SD 3mo]) with developmental coordination disorder (DCD) and their age-matched controls (AMCs). Kinematic data were collected to examine Bernstein's (1967) notion of freezing and releasing degrees of freedom (DF). Participants were asked to catch a ball 30 times, delivered in three blocks of 10 trials. Video analysis showed that children with DCD caught significantly fewer balls than their AMCs (p< or =0.001) counterparts. Kinematic analyses showed that children with DCD exhibited smaller ranges of motion and less variable angular excursions of the elbow joints than their AMCs, and that their elbows are more rigidly coupled (p< or =0.001). These data suggest that children with DCD rigidly fix and couple their limbs to reduce the number of DF actively involved in the task.     

Neuromotor task training for children with developmental coordination disorder: a controlled trial

The aim of this study was to evaluate neuromotor task training (NTT), a recently developed child-centred and task-oriented treatment programme for children with developmental coordination disorder (DCD). A treatment and a non-treatment control group of children with DCD were included. Children were selected if they scored below the 15th centile on the Movement Assessment Battery for Children (MABC). The children in the treatment group were recently referred for physiotherapy (n=26; 20 males, 6 females; mean age 7y 2mo [SD 1y 3mo]). The parents of the non-treated children were concerned about their children's motor performance and responded to advertisements for free testing (n=13; 10 males, 3 females; mean age 7y 2mo [SD 2y 1mo]). Before and after nine weekly 30-minute sessions of NTT or at least 9 weeks of no intervention, the MABC and the Test of Gross Motor Development - 2 (TGMD-2) were administered. Therapists reported per session on treatment goals and tasks trained. The results indicate that motor performance does not improve spontaneously and that NTT is effective. During the intervention period, only the treated group improved on the MABC and the TGMD-2. Children improved most on tasks similar to those trained. In older children with poorer motor patterns, NTT's treatment success was higher. The Child Behavior Checklist subscales withdrawn, thought problems, anxious/depressed, and delinquency were determinants of effects on motor patterns.     

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.     

Deficient coordination of associated postural adjustments during a lifting task in children with neurodevelopmental disorders

Precision grip and concomitant anticipatory postural adjustments were investigated in 11 children (three females, eight males; mean age 9 years 1 month, SD 11 months) with attention-deficit-hyperactivity disorder (ADHD); 12 children (three females, nine males; mean age 9 years, SD 7 months) with developmental coordination disorder (DCD), and 13 children (two females, 11 males; mean age 9 years 9 months, SD 11 months) with a combination of ADHD and DCD (ADHD+). There were two comparison groups: an age-matched group (four females, 11 males; mean age 9 years 1 month, SD 14 months) and a younger age group (five females, six males; mean age 6 years 5 months, SD 8 months). Adaptation to different weights was evaluated by lifting a specialized grip instrument monitoring grip force, load force, and centre of foot pressure displacements. Children with ADHD+ showed: (1) excessive grip forces, (2) decreased amplitude and prolonged onset of postural adjustments, and (3) reduced ability to adapt the motor output. Children with ADHD and DCD did not scale manual and postural forces in amplitude and time domains. Children with DCD also differed in delayed timing of postural adjustments. Results indicate that children with ADHD and DCD show a spectrum of neural dysfunctions underlying poor motor coordination, which are not specific to the clinical disorder.     

Fine motor skills and effects of methylphenidate in children with attention-deficit-hyperactivity disorder and developmental coordination disorder

The aims of this study were to investigate fine motor skills of children with both attention-deficit-hyperactivity disorder (ADHD) and developmental coordination disorder (DCD) and those of a control group, and to examine the effects of methylphenidate on these skills. A group of 12 children with ADHD-DCD (11 males, one female; mean age 9y 8mo [SD 1y 7mo]) and 12 age- and sex-matched controls (mean age 9y 7mo [SD 1y 2 mo]) participated. The manual dexterity subtests of the Movement Assessment Battery for Children, the concise assessment method for children's handwriting, and a computerized graphomotor task were used. Results demonstrated that children with ADHD-DCD performed more poorly on the manual dexterity subtests, had poorer quality of handwriting, and drew more rapidly, more fluently, but less accurately than controls on the graphomotor task. On methylphenidate, manual dexterity and quality of handwriting improved, and strokes on the graphomotor task became less fluent but more accurate. ADHD is characterized by persistent symptoms of inattention, impulsivity, and hyperactivity, affecting 3 to 5% of school-age children. Up to 50% of children with ADHD also have motor coordination problems that are severe enough to meet criteria for DCD. In DCD, children demonstrate functional motor performance deficits not explained by the child's (chronological) age or intellect, or by other neurological or psychiatric disorders.     

Grip force coordination during bimanual tasks in unilateral cerebral palsy

Aim The aim of the study was to investigate coordination of fingertip forces during an asymmetrical bimanual task in children with unilateral cerebral palsy (CP). Method Twelve participants (six males, six females; mean age 14y 4mo, SD 3.3y; range 9–20y;) with unilateral CP (eight right‐sided, four left‐sided) and 15 age‐matched typically developing participants (five males, 10 females; mean age 14y 3mo, SD 2.9y; range 9–18y,) were included. Participants were instructed to hold custom‐made grip devices in each hand and place one device on top of the other. The grip force and load force were recorded simultaneously in both hands. Results Temporal coordination between the two hands was impaired in the participants with CP (compared with that in typically developing participants), that is they initiated the task by decreasing grip force in the releasing hand before increasing the force in the holding hand. The grip force increase in the holding hand was also smaller in participants with CP (involved hand/non‐dominant hand releasing, p<0.001; non‐involved hand/dominant hand releasing, p=0.007), indicating deficient scaling of force amplitude. The impairment was greater when participants with CP used their non‐involved hand as the holding hand. Interpretation Temporal coordination and scaling of fingertip forces were impaired in both hands in participants with CP. The non‐involved hand was strongly affected by activity in the involved hand, which may explain why children with unilateral CP prefer to use only one hand during tasks that are typically performed with both hands.     

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.     

Evaluation of the Developmental Coordination Disorder Questionnaire as a screening instrument

Reliability and validity of the Developmental Coordination Disorder Questionnaire (DCD-Q) was assessed using a population-based sample of 608 children (311 males, 297 females; mean age 7 y 8 mo [SD 2 y 4 mo]), a sample of 55 children with DCD referred to a rehabilitation clinic, and a control sample of 55 children matched for age and sex (48 males, seven females in each sample; mean age 8 y 3 mo [SD 2 y]). The DCD-Q is reliable and valid in the age range for which the questionnaire was developed(8 y-14 y 7 mo) and in a younger age range (4-8 y). Sensitivity and specificity of the DCD-Q was assessed using the Movement Assessment Battery for Children as the criterion standard. The DCD-Q met the standard for sensitivity (80%) in the clinic-referred sample (81.6%), but not in the population-based sample (28.9%). Specificity almost reached the standard of 90%: 89% in the population-based sample and 84% in the clinic-referred sample.     

Neuromotor development in nocturnal enuresis

In children with nocturnal enuresis, a higher rate of minor neurological dysfunction has been found. The aim of this study was to assess timed performance (a measure of motor performance speed) and associated movements using a standardized and reliable instrument. The motor function of 37 children with nocturnal enuresis (27 males, 10 females; mean age 10y 7mo [SD 1y 10mo]; age range 8y-14y 8mo) and 40 comparison children without enuresis (17 males, 23 females; mean age 10y 7mo [SD 1y 6mo]; age range 8y-14y 8mo) was assessed using the Zurich Neuromotor Assessment. Children with nocturnal enuresis showed a slower motor performance than comparison children, particularly for repetitive hand and finger movements. This study provides evidence for a maturational deficit in motor performance in children with nocturnal enuresis. In addition to a maturational deficit of the brainstem, it is proposed that there is a possible maturational deficit of the motor cortex circuitry and related cortical areas in children with nocturnal enuresis.     

No association between the 2D:4D fetal testosterone marker and multidimensional attentional abilities in children with ADHD

Aim It has been suggested that high levels of prenatal testosterone exposure are implied in the aetiology of attention‐deficit–hyperactivity disorder (ADHD). This study examined the association between the ratio of the length of the second and fourth digits (2D:4D ratio), a marker of fetal testosterone exposure, and the presence of ADHD‐related cognitive and behavioural problems in children with ADHD and in typically developing comparison individuals. Method A clinically referred group of 64 children who fulfilled DSM‐IV‐TR criteria for ADHD (47 males, 17 females; mean age 8y 8mo, SD 1y 8mo, range 7–12y) and 46 comparison children (25 males, 21 females; mean age 9y 2mo; SD 1y 10mo, range 7–12y) were included in the study. The length of the second and fourth digits was measured by two independent raters. The Child Behaviour Checklist (CBCL) and the Test of Everyday Attention for Children (TEA‐Ch) were used to assess behavioural problems and different aspects of attention. Results No group differences in 2D:4D ratio were observed between children with (combined, inattentive, or hyperactive‐impulsive subtype of) ADHD and comparison children. The ratio did not show the postulated relation with cognitive and behavioural aspects of ADHD. Interpretation These findings challenge the hypothesis that fetal testosterone exposure plays a prominent role in the aetiology of ADHD.