Neuromotor and clinical definition in young children with autism

Abstract

Motor dysfunction represents a prevalent neurological feature of autism that may provide an indication of neurobiological underpinnings, clinical diagnosis, prognosis and treatment, particularly early in the disorder. A number of studies have set out to characterise motor dysfunction in autism, however, a majority of this research has focused on older children (above 7 years) and those who demonstrate average range intellectual functioning (IQ>80). The aim of the current thesis was to examine and characterise motor function in young children with autism (3 to 7 years), across the spectrum of cognitive ability. This was undertaken using innovative methodologies that may provide a new approach to characterising motor dysfunction in children with autism. Chapter 3 examined coordinated, whole-body movement in a rise-to-stand task (commenced from the supine position) in young children with autism, including children with an intellectual disability (low-functioning) and without (high-functioning). Observational and temporal analysis revealed that only blind-rated balance and stability distinguished the children with high-functioning autism, who otherwise demonstrated grossly intact form and timing of movement relative to intellectually-matched children. Children with low-functioning autism were not found to perform the rise-to-stand movement differently from intellectually-matched children. Chapter 4 examined upper-limb motor kinematics in children with high-functioning autism using a point-to-point movement paradigm presented on a touch screen. Children with autism demonstrated increased variability in movement planning time, relative to typically developing children. No differences in the temporal execution of movement were found. When a visual distractor was introduced nearby the target of the point-to-point movement, it was found that the children with autism did not change their movement to adjust for this distractor. In contrast, typically developing children made several temporal adjustments in their movement planning when a distractor was present. Together, the findings from Chapters 3 and 4 illustrate the subtlety of the motor profile exhibited by children with autism. Chapter 5 examined the association between motor function as measured on a standardised clinical motor assessment battery, and anxiety, another associated feature of autism. The findings revealed that dynamic balance dysfunction was associated with increased anxiety in children with high-functioning autism, indicating an inter-relationship between motor dysfunction and psychological features of autism. The close relationship between motor and perceptual function in autism formed the basis for Chapter 6, which examined the suggestion that an overlap in behavioural definitions underlies the relationship between sensory defensiveness and anxiety in autism. The study found support for the behavioural overlap hypothesis. The findings from Chapters 5 and 6 highlighted the importance of multidisciplinary management for children with autism, and also the need to consider motor and sensory dysfunction in autism in the context of the social and behavioural features of the disorder. The findings from this thesis are discussed in terms of the motor trajectory of autism, the clinical conceptualisation of the disorder, and the confounding variables associated with the measurement of motor and perceptual function in autism.