I have found in my experience that yes weed worsens my ADHD. However I’ve never been drug tested for it by my doctor. The only justifiable reason I could imagine would be if they put you on a medication where there are known drug interactions, or something, but even then it seems a bit odd to me. It sounds like this is an atmosphere that comes from their substance abuse specialization.
Similar for me – but add onto it, when I joined, lemmy.world was the only one of the top 3 most populated instances (with lemmy.ml and beehaw) that had open registration