How does early motor development influence subsequent cognitive ability?

神经发育障碍（如发育迟缓、自闭症谱系障碍（ASD）、注意力缺陷多动障碍（ADHD））影响了英国3-4%的儿童。虽然一些神经发育障碍可以在出生前或出生前诊断出来（如唐氏综合症），但对其他疾病（如自闭症）的早期诊断具有挑战性，因为早期诊断依赖于儿童社交和沟通技能的非典型发展。然而，在这个相对较晚的发育阶段，这些缺陷会变得非常虚弱。目前，神经发育障碍的筛查是基于认知缺陷（DSM-5），忽视了早期运动发育的质量和数量中嵌入的神经发育疾病风险的潜在早期标记。由于缺乏对认知能力发展的展开和支持过程的关注，这种临床实践导致相对较晚的诊断和抑制早期干预。越来越多的文献表明，早期运动能力是所有认知领域的基础。例如，一般运动异常的最早例子先于认知缺陷，早期运动特征的质量（即，正常可变运动特征vs单调运动特征）一直被发现不仅是运动相关疾病的有力预测因素，而且是儿童后期认知表现差的有力预测因素。例如，临床评估表明，在出生后的前8周内持续出现异常运动行为（如坐立不安）的儿童在学龄期的认知得分较低，而3-5个月间的异常姿势与7-10岁时的认知结果较差有关。为了有效地与环境互动，婴儿必须掌握复杂多变的动作技能。对环境的自发探索可以让婴儿获得丰富的感知和社会信息，这对发展社交和沟通能力很有用。这意味着婴儿早期缺乏“平滑的”可变运动技能可能会阻碍婴儿与环境互动的能力。这些例子说明了发展级联框架的一个关键特征——它将运动和认知行为在看似无关的领域联系起来。重要的是，它提出了关于一个领域早期中断对另一个领域发展的潜在影响的开放性问题。因此，从发展级联的角度来看，早期的运动技能可能为以后的认知技能习得提供有价值的信息。运动能力受损的证据可以在一系列行为和模式中发现（例如，姿势、手灵巧性、眼睛注视）。例如，神经正常的婴儿倾向于脸，喜欢脸而不是其他刺激，喜欢生物而不是非生物运动。然而，回顾性研究表明，后来接受神经发育诊断的儿童需要更长的时间来适应面孔，花更少的时间看面孔，并且更喜欢非生物运动。此外，当神经正常的儿童在物体相互作用中发展出平滑的运动时，神经发育障碍的儿童往往表现出手协调缺陷（例如，阅读障碍、运动障碍、发育协调障碍）。这项研究暗示了早期运动发育在新兴认知能力中的核心作用，以及它们在神经发育障碍中的级联破坏。此外，这表明早期运动和沟通能力的差异和延迟可能对后来的社会沟通和认知技能以及其他领域的行为发展产生下游影响。

Neurodevelopmental disorders (e.g., developmental delays, autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD)) affect 3-4% of children in England. Although some neurodevelopmental disorders can be diagnosed before or at birth (e.g., Down's syndrome), early diagnosis is challenging in others (e.g., autism), when it relies on atypical development of children's social and communication skills. However, by this relatively late developmental stage, these deficits can become highly debilitating. Currently, screening for neurodevelopmental disorders is based on cognitive deficits (DSM-5), neglecting potential early markers of risk for neurodevelopmental conditions embedded within the quality and quantity of early motor development. This clinical practice results in relatively late diagnoses and inhibits early intervention due to a lack of focus on the unfolding and supporting processes giving rise to development of cognitive abilities. A growing literature has demonstrated early motor abilities to be fundamental across all cognitive domains. For example, the earliest examples of general motor abnormalities precede cognitive deficits, with the quality (i.e., a normal variable motor repertoire vs a monotonous repertoire) of early motor repertoire is consistently found to be a powerful predictor of not only motor-related disorders but poor cognitive performance in later childhood. For example, clinical assessments indicate that children with consistently abnormal motor behaviour (e.g., fidgety movements) during the first 8 weeks of life have lower cognitive scores at school age, while abnormal posture between 3-5 months is associated with poor cognitive outcomes at 7-10 years. To interact with their environment effectively, infants must obtain a complex and variable motor repertoire. Spontaneous exploration of their environment allows an infant to access rich perceptual and social information that is useful for developing social and communication abilities. This implies that the absence of a "smooth" variable motor repertoire in early infancy may hinder an infant's ability to interact with the environment. These examples illustrate a key feature of the developmental cascade framework - it links developing motor and cognitive behaviours in seemingly unrelated domains. Importantly, it raises open questions regarding the potential effects of early disruptions in one domain on development of another. Thus, from the development cascade perspective, early motor repertoire may provide valuable information about later cognitive skills acquisition. Evidence of disrupted motor ability can be found across a range of behaviours and modalities (e.g., postures, manual dexterity, eye gaze). For example, neurotypical infants tend to orient towards faces, prefer faces over other stimuli and prefer biological over non-biological motion. However, retrospective studies indicate that children who later receive a neurodevelopmental diagnosis take longer to habituate to faces, spend less time looking at faces, and prefer non-biological motion. Moreover, while neurotypical children develop smooth movements during object interaction, children with neurodevelopmental disorders often show manual coordination deficits (e.g., dyslexia, dyspraxia, developmental coordination disorder). This research implicates a central role of early motor development in emerging cognitive abilities, and their cascading disruption in neurodevelopmental disorders. Further, it suggests that differences and delays in early motor and communication abilities may have downstream effects on later social-communication and cognitive skills, as well as on the development of behaviours in other domains.