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.     

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.     

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.     

Co-occurrence of developmental delays among preschool children with attention-deficit-hyperactivity disorder

The aim of this study was to provide a comprehensive profile of the sensory, motor, language, and intellectual functioning of a non-referred community sample of 49 preschool children with attention-deficit-hyperactivity disorder (ADHD; 39 males, 10 females; mean age 4y 7mo [SD 7mo]; range 3y 10mo-6y) and 48 typically developing children (38 males, 10 females; mean age 4y 8mo [SD 6mo]; range 3y 11mo-6y) matched by age, sex, and maternal education who underwent a broad battery of neurodevelopmental tests. The results showed that the scores of the ADHD group were significantly lower than the comparison group on all measures. In addition, 23 (47%) of the children with ADHD had clinically significant co-occurring deficits in two or more areas. Logistic regression indicated that the only significant predictors of group classification were scores of verbal intelligence and motor and sensory functioning, accounting for 44.1% of the variance. These findings suggest that preschool children with ADHD have multiple developmental deficits over and above the core symptoms of ADHD and emphasize the importance of evaluating the sensorimotor functioning of preschool children with ADHD symptoms.     

Sex differences in tactile defensiveness in children with ADHD and their siblings

Tactile defensiveness (TD) is a disturbance in sensory processing and is observed in some children with attention-deficit-hyperactivity disorder (ADHD). TD has been examined in male children with ADHD and in children with ADHD without differentiating by sex. As males and females with ADHD may differ in the clinical expression of the disorder and associated deficits, the aim of this study was to examine sex differences in TD in males and females with ADHD. Non-affected siblings were also examined to investigate familiality of TD. The Touch Inventory for Elementary-School-Aged Children was administered to 47 children with ADHD (35 males, 12 females; mean age 9y 8mo [SD 1y 11mo]), 36 non-affected siblings (21 males, 15 females; mean age 8y 10mo [SD 2y 4mo]), and 35 control children (16 males, 19 females; mean age 9y 5mo [SD 6mo]). Results indicated that females with ADHD displayed higher levels of TD than males with ADHD (who did not differ from control males). This suggests that TD is sex specific and may contribute to the identification of ADHD in females, thus improving diagnostic and therapeutic strength in this under-referred group. Non-affected siblings were unimpaired, regardless of sex, which suggests that TD is specific to the disorder and not part of a familial risk for ADHD.     

Differentiating attention deficits in children with fetal alcohol spectrum disorder or attention‐deficit–hyperactivity disorder

Aim The attention and inhibition problems found in children with attention‐deficit–hyperactivity disorder (ADHD) are also common in children with fetal alcohol spectrum disorders (FASDs). Attempts to distinguish ADHD from FASDs in terms of these deficits are rare and were pursued in this study. Method A total of 116 children (47 with ADHD, 31 males, 16 females; 30 with FASDs, 17 males, 13 females; and 39 comparison children, 20 males, 19 females) participated. The mean age was 9 years 4 months (SD 1y 8mo) in the ADHD groups, 8 years 10 months (SD 1y 2mo) in the FASD group, and 9 years 1 month (SD 1y 1mo) in the comparison group. Sustained attention was tested with a slow event rate continuous performance task (CPT). Inhibitory control was tested with both a slow and fast event rate Go/No‐Go task. Results On the CPT task, children with ADHD, combined type (ADHD‐C), ADHD, primarily inattentive type (ADHD‐PI), and FASDs showed greater declines in task performance as a function of time than comparison children, suggesting sustained attention problems in all clinical groups. Children’s Go/No‐Go performance was event‐rate dependent, with the ADHD‐C group being affected in the slow condition and the ADHD‐PI and FASD groups having problems with the fast condition. Interpretation Children with ADHD‐C are typically impaired in handling understimulation, while children with FASDs may have problems with overstimulation. The dissociation in responsivity to event rate between groups may have significant differential diagnostic value.     

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

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

Strength, power, and coactivation in children with developmental coordination disorder

Strength, power, and coactivation levels were measured during knee extension and flexion tasks in 20 children (13 males, 7 females) with developmental coordination disorder (DCD) and 20 age-matched control children (12 males, 8 females). Participants were classified according to results obtained on the McCarron Assessment of Neuromuscular Development, with each group including two age levels: 6 to 7 and 9 to 10 years. Tasks were performed on a Biodex dynamometer under isometric and isokinetic conditions with surface EMG recorded from the vastus lateralis and biceps femoris muscles. Significant effects of group and age were observed for the measures of peak torque (isometric and isokinetic) and power, with the decreased power in the group with DCD being more apparent at higher velocities. A lower flexor-extensor percentage was recorded for the group with DCD but only under isokinetic conditions. From a neuromuscular perspective, the group with DCD had increased levels of coactivation (RMS agonist:RMS antagonist) during the isometric flexion and isokinetic extension actions. Possible causes of the strength and power deficits observed in children with DCD are discussed.     

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

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

Effects of methylphenidate on quality of life in children with both developmental coordination disorder and ADHD

Measurement of health-related quality of life (HRQOL) in attention-deficit-hyperactivity disorder (ADHD) gives a more complete picture of day-to-day functioning and treatment effects than behavioural rating alone. The aim of this pilot study was to investigate the impact of the combined diagnoses of developmental coordination disorder (DCD) and ADHD on HRQOL, and the effectiveness of methylphenidate (MPH) on HRQOL. HRQOL was established using the Dutch-Child-AZL-TNO-Quality-of-Life (DUX-25) and the TNO-AZL-Child-Quality-of-Life (TACQOL) questionnaires, completed by children and parents. HRQOL of these children was compared with that of 23 age- and sex-matched healthy controls. Twenty-three children (21 males, two females; mean age 8 y 6 mo, [SD 3 mo] range 7 y-10 y 8 mo) with ADHD/DCD entered a 4-week, open-label MPH study, after MPH-sensitivity was established, in a double-blind, placebo-controlled trial. In these children's self- and proxy reports, impact of both DCD and ADHD was reflected in lower general well-being (self and proxy report p=0.001) due to lower functioning in motor (selfp=0.026; proxy 0.001), autonomic (self p<0.001; proxy p=0.047), cognitive (self p=0.001; proxy p=0.01), and social (self and proxy p<0.001) domains. HRQOL scores improved in 18 children receiving MPH (p=0.001) versus controls. The ADHD /DCD group also demonstrated a significant improvement in ADHD symptoms (p<0.001) and motor functioning (p<0.001). Additional motor therapy will still be needed in about half of the children with ADHD/DCD receiving MPH, within multimodal treatment including educational and psychosocial assistance.     

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.     

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.     

Effect of a social skills training group on everyday activities of children with attention-deficit-hyperactivity disorder

This preliminary study compared the daily living skills of children with and without attention-deficit-hyperactivity disorder (ADHD), and the influence of a social skills training group on these skills. Twenty-seven children with ADHD (2 females, 25 males; age range 5 to 8y, mean 6y 6mo, SD 10mo), and 24 children without ADHD (8 females, 16 males; age range 5 to 8y, mean 6y 11mo, SD 10mo) performed the Assessment of Motor and Process Skills (AMPS). Fourteen of the children with ADHD used medication daily. Nine of the total group with ADHD were randomly selected to attend group treatment which focused on social skills training, through meaningful occupations (e.g. art, games, cooking). Children were evaluated at the beginning of group treatment and after 10 sessions. Ten children without ADHD were evaluated at similar intervals. Children with ADHD initially achieved significantly lower scores on the AMPS in all process skills (p<0.001) and in the coordination motor subtest (p<0.005) than children without ADHD. Children with ADHD significantly improved from the first to the second evaluation and no longer differed from the children without ADHD after treatment (p<0.008). The results emphasize the need for a focus upon occupation in assessment and treatment of children with ADHD.     

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.     

Deficits in motor control processes involved in production of graphic movements of children with attention-deficit-hyperactivity disorder

This study aimed to investigate whether two distinct motor control processes, i.e. motor planning and parameter setting, were impaired in children with attention-deficit-hyperactivity disorder (ADHD). An experiment was designed in which children copied figures of increasing complexity under increasing accuracy levels on a digitizer. Sixteen children with ADHD (11 males, 5 females; mean age 8 y 4 mo, SD 1 y 1 mo) and 16 comparison children, without impairment, matched for age and sex participated. ADHD was diagnosed by a psychiatrist following the criteria of the DSM-V. Only children with IQ scores greater than 80 were included. Across all graphic tasks, children with ADHD made slower, inaccurate strokes with relatively high axial pen force compared with the comparison group. No evidence was found for a deficit in motor planning, but parameter setting appeared to be deficient as the ADHD group made less accurate strokes when accuracy demands increased.     

Evaluating physical activity using accelerometry in children at risk of developmental coordination disorder in the presence of attention deficit hyperactivity disorder

Physical activity (PA) is compromised in children and adolescents with developmental coordination disorder (DCD). Approximately half of all children with DCD suffer from attention-deficit hyperactive disorder (ADHD); a cohort often considered more physically active than typically developing youth. Accelerometry is an effective method of assessing physical activity patterns; although estimates of PA in children with DCD using this quantifiable method have not been attempted. We hypothesize that children with co-morbid DCD/ADHD will be more physically active than children with DCD and healthy peers. Therefore, the purpose of this study was to contrast physical activity (step count and activity energy expenditure using accelerometry [AEE]) between children with DCD, co-morbid DCD and ADHD (DCD/ADHD), and healthy controls. A sample of 110 children with DCD (N = 32), DCD/ADHD (N = 30) and controls (N = 48) age 12-13 years agreed to participate. Co-morbid DCD/ADHD was present in nearly half of the children with DCD (48.4%). Analysis of covariance demonstrated a positive interaction for females step count (F[1,92] = 4.92, p = 0.009). A significant group difference for step count (F[1,92] = 4.43, p = .04) was identified in females. Post hoc comparison tests identified significantly lower step count between males with DCD and controls (p = .004) and males with DCD/ADHD and controls (p = 0.003). Conversely, females with DCD/ADHD had significantly more step counts than their controls (p = .01). Hyperactivity in females with DCD/ADHD appears to contribute to more physical activity, whereas DCD may contribute to decreased activity in males with DCD and DCD/ADHD. Hyperactivity expressed among girls with DCD/ADHD appears to override the hypoactive behavior associated with females with DCD. Conversely, the expression of hyperactivity among boys with DCD/ADHD does not translate as hypothesized. The contrasting expression of physical activity (i.e., step count and AEE) evaluated using accelerometry in boys and girls with DCD, co-morbid DCD/ADHD and healthy peers are intriguing and constitute further investigation in a larger investigation.     

Response switching process in children with attention-deficit–hyperactivity disorder on the novel continuous performance test

We examined the effects of previous trials on subsequent trials on performance in the continuous performance test (CPT) in children with attention-deficit–hyperactivity disorder (ADHD). Thirty-five non-medicated children with ADHD (31 males, four females; mean age 9y 10mo [SD 2y 4mo]) and 33 comparison children (20 males, 13 females; mean age 10y [SD 2y 7mo]) were tested using a novel CPT, in which stimuli were presented with 50% target probability. Reaction time, reaction time variability, omission, and commission error rate were analyzed for two different types of trials in which different responses (switched trials) or the same responses (repeated trials) were required for two consecutive trials. Compared with the comparison group, children with ADHD showed a greater increase in commission error rate from repeated to switched trials, i.e. increased switch cost for commission error rate. On the other hand, omission error rate was not influenced by the previous trial in both ADHD and comparison groups. These results suggest that children with ADHD have trouble in response switching when an inhibitory process is involved.     

Response switching process in children with attention-deficit-hyperactivity disorder on the novel continuous performance test.

We examined the effects of previous trials on subsequent trials on performance in the continuous performance test (CPT) in children with attention-deficit-hyperactivity disorder (ADHD). Thirty-five non-medicated children with ADHD (31 males, four females; mean age 9y 10mo [SD 2y 4mo]) and 33 comparison children (20 males, 13 females; mean age 10y [SD 2y 7mo]) were tested using a novel CPT, in which stimuli were presented with 50% target probability. Reaction time, reaction time variability, omission, and commission error rate were analyzed for two different types of trials in which different responses (switched trials) or the same responses (repeated trials) were required for two consecutive trials. Compared with the comparison group, children with ADHD showed a greater increase in commission error rate from repeated to switched trials, i.e. increased switch cost for commission error rate. On the other hand, omission error rate was not influenced by the previous trial in both ADHD and comparison groups. These results suggest that children with ADHD have trouble in response switching when an inhibitory process is involved.