I don't really know the situation in the US. Here in Germany it is for sure rigorous.

I had three appointments and lots of questionnaires to fill out at home that were designed to exclude all kind of conditions. And with a diagnosis I was still far away from getting a prescription, that is whole other hurdle.

As for the US, well the CDC says in the section for conditions that must be met:

> The symptoms are not better explained by another mental disorder (such as a mood disorder, anxiety disorder, dissociative disorder, or a personality disorder). The symptoms do not happen only during the course of schizophrenia or another psychotic disorder.

https://www.cdc.gov/adhd/diagnosis/index.html

So it is pretty clear on that.