I once read that intelligent people suffering from depression are more difficult to treat. It seems they are more prone to question advice.

Still, I don't know if the premise of this thread is accurate as my experience with family members is that the less intelligent they are, the less they are likely to go to therapy at all. That being said, my brother who considers himself "stupid" has recently started individual therapy by court order and has found it so helpful that he wants to continue it after his required sessions end. I could not ask for better news.