Introduction

Developmental coordination disorder is defined by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, as a condition characterized by severe deficits in the development of motor coordination that significantly interfere with activities of daily living or life progression, that are significantly below the expected level for age and intellectual ability, and that are not due to a general medical condition or severe learning disability (1). A child with developmental coordination disorder may have difficulty analyzing information from the environment, using this information to select an appropriate and desired course of action, sequencing individual movements, sending the correct signals to produce a coordinated action, or integrating all of these factors to control movement. As a result, the child's movements appear clumsy and unskilled, and he or she may have difficulty learning and performing new motor tasks (2). There is considerable evidence that the disorder persists into adulthood and often leads to secondary emotional and social problems such as low self-esteem, low self-esteem, introversion, anxiety, and depression (3).

The causes of this disorder are still not precisely known and are mostly multifaceted. Existing hypotheses emphasize developmental aspects and organ immaturity. Among the hypothesized contributing causes, we can mention neonatal problems and birth problems, malnutrition, inadequate stimulation, psychosocial factors, unreasonable expectations, delayed brain maturation, and neurological disorders, none of which have been conclusively confirmed by research (4). Although the cause of DCD is still not clearly known, children with DCD have distinct deficits in motor control deficits, neurological limitations, and mild neurological symptoms compared to normal children. A number of researchers have developed hypotheses from neurobehavioral models of intra- and intersensory function that seem to be related to the mechanism of DCD in dysfunction of the right hemisphere or dysfunction of the corpus callosum (4).

In terms of neuroimaging, technological advances have helped us understand the neural underpinnings of motor processes and the dynamic interaction of the brain and the environment during development (e.g., fMRI, EEG, TMS, and ERP studies). One tool that allows us to neuroimaging to examine cognitive processes during the performance of various tasks is the event-related potential (ERP). ERP measures brain responses that are directly the result of sensory, cognitive, and motor events (5). In short, event-related potentials are a more advanced method than electroencephalography to extract sensory, cognitive, and motor events using simple averaging techniques during task performance (6). Research has shown that the N200 component (200 to 350 thousandths of a second after stimulus presentation) in the ERP graph generally reflects the cognitive control of execution (8). It seems that the use of such a precise tool for neuropsychological studies in motor behavior research is empty. The assessment of motor functional changes along with changes in neurological components will provide a more complete understanding of the mechanisms of the effect of physical activities on performance indicators.

According to the model presented by Morton, it is believed that the problems of DCD children should be considered at three levels: biological, cognitive and behavioral. The observed behavioral problems, such as poor writing, balance, manual dexterity, coordination and time estimation, arise as a result of problems at the biological and cognitive levels (motor planning, motor execution, feedback, timing).

Initially, the literature on DCD focused on behavioral deficits and assumed that the sensorimotor system was functioning abnormally. According to Diazperez et al. (9), studies have shown that individuals with DCD perform poorly in the areas of sensory motor accuracy, visual perception, static balance and postural control, attentional control, strength, temporal and spatial variability, and motor readiness.

The most important area of ​​cognitive investigation is executive function. Executive function refers to the higher-order control system that manages novel situations and includes planning/decision-making, error correction, working memory, attentional switching, and adaptive sequencing (3). Children with DCD often have difficulty with complex tasks. They are also impaired in error detection and working memory (10). All of these involve executive processes that are subsumed under the umbrella of executive function. Therefore, executive function in children with DCD is suboptimal (11). Response inhibition is another aspect of executive function. The limited studies that have been conducted in this area have shown that DCD children make more errors in manual response inhibition tasks than their peers (12). The findings of Mirabella et al. (13) also point to a deficit in inhibition in children with DCD. Problems with the organization and integration of this cognitive control mechanism may significantly impair successful adaptation to daily tasks. Kuerne and colleagues examined fMRI during a go/no-go task and reported that DCD children had significantly stronger anterior cingulate activity and weaker prefrontal activity for response inhibition and error detection than their peers. These two areas play a key role in error inhibition and detection (14).

According to Morton's model (15), the question arises whether motor interventions based on experience at the behavioral (motor) level have the ability to affect cognitive infrastructure? Among the problems that DCD children face are deficits in executive and sensorimotor functions, which can be helped through sports activities.

In short, it is hoped that they will be treated at an early age and in the early stages or that the severity of their disorder will be reduced and they will face fewer problems in the future. One of the factors that can play an important role in increasing appropriate practice opportunities for motor skills and motor concepts is play and physical activity (16). Considering the role of play and physical activity on physical and motor, cognitive and emotional development, it seems that play can be considered as an effective factor in the educational program (17).

In a study conducted by Soltaninejad et al. (18) and Ebrahimi-Sani et al. (19) on the effect of perceptual-motor exercises on improving the motor abilities of children with developmental coordination disorder, it was noted that the experimental group performed significantly better in motor tests compared to the control group after undergoing a period of perceptual-motor training. Perez et al. (9) also found that cognitive games play an active role in the acquisition of new skills in children with DCD.

In Tsai's study, soccer training was shown to improve subtests of the MABC and argued that physical training facilitates the development of motor skills (20). Qarabagh et al. (21) stated that physical training improves neuromotor activation by improving strength, coordination between limbs, and complex coordinated movements.

Although DCD is classified in the category of mental disorders, Mahmoudifar et al. (22) stated that poor sensory-motor coordination has long been recognized as a cause of motor problems in children with developmental coordination disorder, and that improving this problem improves the disorder. Therefore, motor enrichment is expected to play a significant role in the treatment of this disorder. As Regent et al. (23) concluded in their study, the majority of children with developmental coordination disorder who are exposed to movement and participation in physical activities will compensate for their delay to some extent, and even 5 of the individuals in their study group reached full ability.

There is limited research that has examined the motor and cognitive functions of children with DCD in detail simultaneously. In particular, a deeper understanding of the executive and motor mechanisms between these two disorders requires further investigation. Also, many previous studies have mainly focused on behavioral functions and have not paid attention to physiological and neural aspects such as event-related potentials (ERPs). This could lead to ignoring the real differences in executive and motor mechanisms between these two disorders. While some studies have shown that individuals with DCD have problems with executive functioning, more research is needed to determine whether these problems are due to similar patterns of brain function. Some studies have shown that individuals with DCD have difficulty with response control tasks compared to normal individuals, while other studies have shown that these differences do not exist in adults with DCD. This may indicate that there is a lack of a clear picture of the effects of these two disorders on executive and motor functioning. In some studies, differences in ERPs have been observed between ADHD and control groups, while other studies have failed to detect these differences. This discrepancy could be due to small sample sizes, differences in research methods, or other factors. Also, some researchers believe that the causes of the disorder are diagnostically distinct, while others emphasize significant overlap between these motor and cognitive causes of the disorder. This lack of agreement can lead to confusion in the diagnosis and treatment of these disorders. In general, it can be stated that the present study aims to fill these scientific gaps and resolve the contradictions in the research literature and examine them more closely. Using new methods, such as measuring ERPs, this study tries to help better understand the executive and motor mechanisms associated with these disorders and provide solutions for more effective interventions. On the other hand, despite the widespread recognition of motor and cognitive problems in children with developmental coordination disorder (DCD), there is still a lack of comprehensive and systematic research on effective interventions. This study can help enrich the scientific literature in this area and provide new information. Although previous studies have shown that motor interventions can help improve motor and cognitive skills, there is still a need for a more detailed investigation of how these interventions affect cognitive and neuropsychological functions. This study examines this issue. Motor and cognitive problems can have profound effects on children's quality of life, including social, emotional, and academic difficulties. By identifying and strengthening effective interventions, we can increase the hope of improving the quality of life of these children. The results of this research can help education professionals, psychologists, and therapists design and implement better intervention programs for children with DCD. Also, this study can help parents and educators better understand the needs of these children. Using neuroscience technologies and advanced tools such as ERP, this research can help to understand cognitive and motor processes in children with DCD more deeply and lead to the development of new and more effective intervention methods. With timely and effective intervention, emotional and social problems can be prevented in adulthood. Overall, it seems that this research can identify methods that

Method: The present study is a comparative and cross-sectional developmental causal study in a semi-experimental manner with an experimental and control group. Participants: The statistical population of this study was boys aged 7-9 in District 22 of Tehran, which, according to the education information of Tehran province, is 6140 people, students of public schools. First, a list of all public elementary schools in District 22 was prepared, then four schools were randomly selected and a link to the questionnaire was sent in internal messengers to all parents of children in the first to third grades of these four schools, which numbered 511 people, and 337 people responded. The statistical sample was based on the G-Power software, which determined the level of error, effect size, and statistical analysis method, and suggested a sample size of 42 people. From among the received questionnaires, the desired number that met the necessary conditions for participation in the study was selected. Next, by providing general information about the study to the parents of children with developmental coordination disorders, children who were likely to have this disorder were identified and tested by a child psychiatrist. At this stage, 42 children were selected, of which only 38 were referred, and 32 of them scored below one standard deviation on the MABC-2 test. Again, four of these were suspected of having attention deficit and were excluded from the study. 28 samples were randomly selected and purposefully distributed into two groups: children with the disorder (14) and normal children (14). Since this study is looking for special or unusual cases, purposive sampling was used. This means that the subject is selected based on the researcher's judgment or the study's objectives. Then, 28 children with DCD were selected from among them. The reason for selecting seven-year-old children was that this age is the only age at which children are officially evaluated by the Ministry of Health and Education for entry into the first grade of primary school.

Results: As shown in Table 3, there is a significant difference between the two groups in the delay time of the N200 component in the Fz, F4, C3 and P4 regions, but no significant difference is observed in the Fp1, Fp2, F3, F7, F8, Fz, Cz, C4 and P3 regions.

Table 4 The results of the subtests of the Children's Movement Assessment Test set show that in this table, the variables were first examined individually, then in their overall score, and finally for the overall score of the test.

Also, the Shapiro-Wilk test was used to examine the assumption of homogeneity of covariances. The results of the Shapiro-Wilk test for the post-test of the MABC-2 subtests for the control and experimental groups were, respectively, in the variables of pin placement (0.251 and 0.253), string pulling (0.346 and 0.381), maze drawing (0.521 and 0.418), sandbag throwing (0.251 and 0.253), catching and throwing (0.648 and 0.310), heel-toe walking (0.533 and 0.704), static balance (0.629 and 0.569), and walking (0.490 and 0.591). The results showed that the difference in covariances was not significant and as a result, the assumption of homogeneity of covariances was established, so the assumptions of the analysis of covariance were confirmed. The results of the above tests show that the significance levels of all tests allow the use of multivariate analysis of covariance.

Conclusion:

In general, the findings of this study were consistent with the results of Omer et al., Fogel et al., Nober et al., who reported the effects of perceptual motor training on improving the performance of children with developmental coordination disorder. In this regard, it seems that a positive effect of physical activity on cognitive performance in children with developmental coordination disorder is partly caused by physiological changes in the body, such as increased levels of neurotrophic factors, which facilitate learning and maintain cognitive performance by improving synaptic plasticity, which acts as a neuroprotective factor. One of the possible mechanisms that can be investigated in relation to the effect of physical training on children with developmental coordination disorder is the role of exercise and physical activity in brain plasticity. Exercise may be a strong protective factor against neurodegeneration. Exercise leads to neurogenesis and improved performance on behavioral tests of learning and memory, as well as changes in synaptic plasticity in the dentate gyrus of the hippocampus. The role of neuroplasticity is widely recognized in healthy development, learning, attention, and memory. Research has shown that appropriate experience and environmental stimuli can change both the physical structure and functional organization of the brain. It has been shown that perceptual-motor training plays an important role in the plasticity of the nervous system.

The most commonly reported ERP components of inhibitory activity are the N200 and P300 components of the inhibition task. The N200 and P300 components can reflect initial inhibition and subsequent inhibition, respectively (6). Some researchers argue that the N200 component of the inhibition task represents a top-down inhibitory process that suppresses an incorrect response during the processing stage. The N200 of the inhibition task also reflects the resolution of conflict in the motor program during the evaluation of an inappropriate response (7). In a study involving children and adults, the medial frontal cortex (near the anterior cingulate cortex) was shown to be involved in generating the N200 of the inhibition task. The P300 component has also been studied in tasks that require some form of inhibition and has its origins in the anterior cingulate cortex (8). As previously mentioned, various sites of inhibition have been proposed in the study of the causes of DCD, including the dorsoventral cerebellar network in predictive control, the dorsoventral gyrus in inhibition, the posterior dorsoventral gyrus in internal representation of actions and control, and the dorsoventral frontal network in the perception of invalid cues. MRI studies have also shown that the lateral frontal cortex, the anterior cingulate cortex, and the posterior, posterior, and anterior cingulate cortex are involved in inhibitory activity (8). Conflicting results have also been reported regarding the degree of activation of the left and right lobes of the cerebral cortex. For example, Falgather et al. reported that the central frontal lobe is more active in inhibitory tasks. Perez et al. (9) showed that the right lobe is more active in inhibitory tasks, and Morrison et al. (5) suggested that P300 activity in inhibitory tasks extends to the left hemisphere and that the left frontal region plays a role in executive control of behavior. Therefore, in this study, all electrodes except the occipital and temporal regions were examined to allow for a more complete examination.

The results showed that after the training intervention, the experimental group had significant improvement in seven subtests of "placing pins", "drawing a maze", "throwing a sandbag", "catching and throwing", "heel-to-toe walking", "static balance" and "swinging", and no significant change was observed in the "string pulling" subtest. Therefore, the physical training program has significantly helped to improve the variables that are based on goal setting and balance. The lack of significant changes in the manual dexterity variable of string pulling may be due to their difficulty in coordinating fine motor skills (12).

One of the major advantages of the present study is considering a group of children with normal development, which allows for the comparison of the motor skills of children with developmental coordination disorder after the interventions with the healthy group. As Tsai et al. acknowledged, although the scores of DCD children on the MABC test improved after soccer training, they did not reach the standard scores of children with normal development, indicating that children with developmental coordination disorder have mild signs of neurological deficits in the brain or minimal damage or dysfunction in the brain (30), which causes a disruption in the attentional network (31). The results of this study and a review of the literature on DCD children show that although they are weak in physical activities, physical activity-based interventions improve their motor performance.

Keywords: Developmental Coordination Disorder, Motor Function, Motor Program, Neuropsychological Variability.

Ethical Considerations

Compliance with ethical guidelines

The ethical principles observed in the article, such as the informed consent of the participants, the confidentiality of information, the permission of the participants to cancel their participation in the research. Ethical approval was obtained from the Research Ethics Committee of the University of Islamic Azad University.

Funding

This study was extracted from the Ph.D. thesis of first author at Department of Sport Psychology of Islamic Azad University.

Authors' contribution

All authors contributed equally to the conceptualization of the article and writing of the original and subsequent drafts.

Conflict of interest

The authors declared no conflict of interest.

Acknowledgements

The authors would like to thank all participants of the present study.