**1. Introduction**

Autism Spectrum Disorder (ASD) is diagnosed along a continuum of behavioural variants in social communication and repetitive behaviours [96]. Most individuals on the autism spectrum also experience differences in sensory perception. Some individuals on the spectrum are 'highfunctioning' and able to cope in every day environments, while others are severely affected, non-verbal, and may have co-occurring diagnoses, such as intellectual disability, epilepsy, and/or obsessional, conduct, or mental health disorders. These individuals require substantial support, caring and careful management, and evidence-based, effective interventions.

ASD diagnosis can be detected from as early as 6-months to 1-year of age, although it is more common that children are aged 2-3 years before diagnosis is affirmed. Frequently, higher functioning individuals are not diagnosed until adolescence, or even adulthood. Present figures indicate that approximately 1:50 children are affected worldwide [97], with parent reported prevalence rates even higher in some countries, e.g., 1:38 (2. 6%) in South Korea (Kim, Leventhal, Koh et al., 2011) and 1:29 (3. 5%) in the UK, based on data of 11-year old children (n=13, 287) from the Millennium Cohort Study [19]. Similar prevalence rates have been found across racial, ethnic and socioeconomic groups; it seems that boys are affected more frequently than girls (estimated ration of 4:1), although this may be due to under diagnosis in girls.
