>often where nearly every anti-depressant had been tried, where getting treatment for ADHD

This is actually a somewhat difficult diagnosis to make, especially when diagnosing adult ADHD without the user documenting and bringing in a well defined log of their behavior (and possibly another person to point out things they don't know about themselves).

>ADHD is a highly heterogeneous disorder with a significant comorbidity rate.

Is thing that you read about in literature around it. And even more common than that is the comorbidity of all the above symptoms, that is ADHD and depression + more in autism.