Neural Mechanism of Physical Exercise in Enhancing Executive and Social Functions in Adolescents

Executive functions (EF) refer to goal-directed cognitive processes consisting of three major components including cognitive flexibility (mental flexibility), inhibition (inhibitory control) and working memory. These components interact with each other and play a crucial role in a range of life outcomes including mental and physical health, school and job success and marital harmony. In addition, higher EF is associated with better problem solving, reasoning and planning skills as well as social functions.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterised by social communication and interaction impairments, as well as restricted and repetitive patterns of behavior. Individuals with ASD have EF impairments which are linked to the restricted and repetitive behaviors that characterise this condition. The prevalence of ASD is increasing with as many as 1 in 68 individuals, which further augments the burden to the ASD individuals, their families and society. Hence, it is essential to investigate the underlying mechanism of ASD and design a cost-effective training that can be widely adopted in the community to reduce impairments arising from ASD symptoms.

Importantly, ASD traits occur on a continuum, and increasingly there is recognition of a broader autism phenotype (BAP) in those that show sub-clinical symptoms. Similarly, these individuals also show impairments in executive function and social functions, making this group an important target for the development and implementation of interventions. As such, we can deliver appropriate training at an earlier stage to prevent associated impairments in those with ASD traits. Therefore, instead of ASD, the present study examines the individuals with BAP.

Given EF impairments along with social function deficits are found in the sub-clinical individuals with BAP, is the training pertaining to ASD applicable to these individuals? In prior literature, physical exercise (PE) has been proved to enhance EF and social functions. For instance, regular PE can enhance cerebral blood flow and increase the formation of new blood vessels in a number of brain regions that are involved in EF and social functions. More specifically, PE is shown to enhance the performance of EF in healthy children and pre-adolescents and those with ASD. For example, it was found that PE including jogging significantly decreased the repetitive and off-task behaviors and the level of aggression in individuals with ASD. Nevertheless, although PE is shown to be beneficial to reduce the symptoms and EF as well as social impairments in ASD, whether it produces the same positive outcomes in the non-clinical individuals. To address the research questions listed above, this proposed study aims to investigate whether PE training enhances the EF and social functions in the adolescents with BAP.

Although the benefits of physical exercise have been studied in the ASD, BAP is under studied in prior literature. This proposed study will extend from the current literature to investigate the non-clinical group who have autistic traits with a longitudinal and randomized controlled trial design (RCT). The findings of this proposed study have multiple levels of significance and implications. For instance, if the hypotheses are supported, the PE training which is more cost-effective than psychotherapy in treating EF and social functioning deficits and associated impairments can be promoted to school settings. Ultimately, it can be incorporated to the curriculum of the primary and secondary schools to reduce BAP and associated impairments in the adolescents. Secondly, by examining those with sub- clinical symptoms, this research will contribute to early trainings approaches for the condition. Lastly, this proposed study can also help promote physical activities among adolescents which can further decrease mental and health issues in the local context.