Motor deficits in autism differ from that of developmental coordination disorder

Marie Martel , Livio Finos, Salam Bahmad，Eric Koun, Romeo Salemme, Sandrine Sonié, Pierre Fourneret, Christina Schmitz7 and Alice Catherine Roy

Autism spectrum disorders and developmental coordination disorders are both associated with sensorimotor impairments, yet their nature and specificity remain unknown. In order to clearly distinguish the specificity between the two disorders, children with autism spectrum disorder or developmental coordination disorder presenting the same degree of motor impairment, thus homogeneous profiles, were examined in a reach-to-displace paradigm, which allows the integrity of two main aspects of motor control (anticipation/feedforward control and movement correction/

feedback control) to be separately interrogated. We manipulated children’s previous knowledge of the weight of the object they were to displace: when known, participants could anticipate the consequences of the weight when reaching for the object, prior to contact with it, thus allowing for feedforward control. Conversely, when unknown prior to contact, participants had to cope with the object weight in the displacing phase of the movement, and use feedback control. Results revealed a preserved feedforward control, but an impaired movement execution (atypical slowness) in children with developmental coordination disorder, while children with autism spectrum disorder displayed the opposite pattern with an impaired feedforward control, but a preserved feedback one. These findings shed light on how specific motor impairments might differently characterize developmental disorders and call for motor rehabilitation programmes adapted to each population.

Lay abstract

A vast majority of individuals with autism spectrum disorder experience impairments in motor skills. Those are often labelled as additional developmental coordination disorder despite the lack of studies comparing both disorders. Consequently, motor skills rehabilitation programmes in autism are often not specific but rather consist in standard programmes for developmental coordination disorder. Here, we compared motor performance in three groups of children: a control group, an autism spectrum disorder group and a developmental coordination disorder group. Despite similar level of motor skills evaluated by the standard movement assessment battery for children, in a Reach-to-Displace Task, children with autism spectrum disorder and developmental coordination disorder showed specific motor control deficits. Children with autism spectrum disorder failed to anticipate the object properties, but could correct their

movement as well as typically developing children. In contrast, children with developmental coordination disorder were atypically slow, but showed a spared anticipation. Our study has important clinical implications as motor skills rehabilitations are crucial to both populations. Specifically, our findings suggest that individuals with autism spectrum disorder would benefit from therapies aiming at improving their anticipation, maybe through the support of their preserved representations and use of sensory information. Conversely, individuals with developmental coordination disorder would benefit from a focus on the use of sensory information in a timely fashion.

摘要  自闭症谱系障碍和发育协调障碍都与感觉运动障碍有关，但其性质和特异性尚不清楚。为了清楚地区分这两种障碍之间的特殊性，对表现出相同程度运动障碍的自闭症谱系障碍或发育协调障碍的儿童进行了伸展到移位范式的检查，该范式允许分别询问运动控制的两个主要方面(预期/前馈控制和运动校正/反馈控制)的完整性。我们操纵了孩子们之前对他们要移动的物体的重量的了解：当知道时，参与者可以在接触物体之前预测到物体重量的后果，从而允许前馈控制。相反，当接触前未知时，参与者必须在移动的移位阶段应对物体重量，并使用反馈控制。结果显示，在发育协调障碍儿童中，前馈控制受到保护，但运动执行受损(非典型缓慢)，而自闭症谱系障碍儿童表现出相反的模式，前馈控制受损，但反馈受到保护。这些发现阐明了具体的运动障碍可能如何不同地表现出发育障碍的特征，并呼吁根据每个人口的情况制定运动康复方案。

自闭症谱系障碍的绝大多数人都有运动技能障碍的经历。尽管缺乏对这两种疾病进行比较的研究，但这些疾病通常被贴上额外的发育协调障碍的标签。因此，自闭症的运动技能康复方案往往不是具体的，而是包含在针对发育协调障碍的标准方案中。在这里，我们比较了三组儿童的运动表现：对照组，自闭症谱系障碍组和发育协调障碍组。尽管儿童标准运动评估组合评估的运动技能水平相似，但在伸展到移动任务中，患有自闭症谱系障碍和发展协调障碍的儿童表现出特定的运动控制缺陷。患有自闭症谱系障碍的儿童无法预测物体的特性，但可以纠正他们的动作，就像典型的发育儿童一样。相比之下，患有发育协调障碍的儿童表现得异常迟缓，但表现出较少的预期。我们的研究具有重要的临床意义，因为运动技能康复对这两个群体都至关重要。具体地说，我们的发现表明，自闭症谱系障碍患者将受益于旨在改善他们预期的治疗，可能是通过支持他们保留的表征和使用感觉信息。相反，患有发育协调障碍的人将受益于对及时使用感觉信息的关注。