Why it's time to investigate the overlap between autism and ADHD

The most influential psychiatric handbook prohibited a joint diagnosis of autism and ADHD until 2013. But the link could be significant

Until as late as 2013 a joint (or comorbid) diagnosis of autism and attention deficit hyperactivity disorder (ADHD) was not permitted by the most influential psychiatric handbook, the Diagnostic and Statistical Manual of Mental Disorders (DSM). The DSM is an essential tool in psychiatry as it allows clinicians and researchers to use a standard framework for classifying mental disorders. Health insurance companies and drug regulation agencies also use the DSM, so its definition of what does or doesn't constitute a particular disorder can have far-reaching consequences.

One of the reasons for the prohibition of a comorbid diagnosis of autism and ADHD was that the severity of autism placed it above ADHD in the diagnostic hierarchy, so the inattention that is normally present in autism did not seem to merit an additional diagnosis. Nevertheless, that was an odd state of affairs, as any clinician working in the field would be able to quote studies that point to anything from 30% to 80% of patients with autism also having ADHD. More problematic still is the fact that patients with both sets of symptoms may respond poorly to standard ADHD treatments or have increased side effects.