The new criteria for ASD in the DSM-5 may influence the incidence of ASD as the diagnosis between people may now differ based on timing rather than symptoms (e.g. a person diagnosed in 2004 compared to a person diagnosed in 2015). The DSM-5 makes use of severity to tackle the difficulty disentangling whether symptoms are due to ASD or due to another comorbid disorder. The DSM has changed the ASD criteria to improve the precision of diagnosis (1), characterize the ASD symptoms within a single name (2) and use a description of severity level (3).

ASD does not need to be a life-long disabling condition. With intervention, children may either lose diagnosis or be included in regular education classrooms. However, a lot of children diagnosed with ASD remain non-verbal throughout their lives, although this number has been declining as the quality of intervention has been improving.

Early intervention leads to better outcomes than later intervention when it comes to ASD. The “wait and see” method may lead to significant negative outcomes. Early interventions also save money as later interventions need to be more intensive for a longer period of time and are thus more expensive.

Individuals with ASD often show aggression (1), tantrums (2) and self-injury (3). The disruptive, secondary symptoms of ASD often have a communicative function. Early intervention, which may improve verbalisation, may reduce these secondary symptoms. Comorbid symptoms are often related to difficulties with socialization and this may thus be reduced as well as a result of early intervention.

Parents experience stress when a child has a disability. This could reduce their ability to parent, leading to worse outcomes and more stress. Early intervention could provide parents with tools to address symptoms and this could lead to more self-confidence and a feeling of empowerment, allowing parents to parent more effectively which leads to even better outcomes.

Early intervention treatments are often seen as experimental since there are no RCTs yet. However, this may help demonstrate the efficacy of these treatments but is not necessary. RCTs may not necessarily work in demonstrating efficacy in behavioural interventions for ASD because of several reasons:

• Individuals with ASD are very heterogeneous making it difficult to ascertain which participants respond to a specific intervention and to what degree.
• It may be impossible to have a non-intervention control group for young children with ASD.
• The treatment effects are often not significant at the group level because of the heterogeneity of ASD.

While there may not be a lot of RCTs, there are a lot of valid and sound single-case studies. It may be more beneficial to treat behavioural dysfunction even when there is no disorder as the cause than waiting to see if it is indeed because of a disorder.