Twenty years ago, autism was largely considered by both clinicians and academics as a relatively complex, all-encompassing condition. For example, attention deficits, executive functioning difficulties, mood dysregulation, and intellectual disability, were each generally considered and discussed as either core to the condition of autism itself or largely attributable to the direct and indirect impacts of autism. A formal example of this is reflected in the fact that Autism and Attention-Deficit/Hyperactivity Disorder (ADHD) could not be co-diagnosed until the publication of the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5; American Psychiatric Association,
2013). Part of the rationale for excluding co-diagnosis of Autism and ADHD prior to this was the belief that ADHD and associated attentional and executive dysfunction were either core to autism or driven directly by the presence of autism, as opposed to a separable co-occurring condition (American Psychiatric Association,
2000; Craig et al.,
2016). …
