Husband with ADHD seems like he has to be right all the time

I'm new to this forum and my husband has been diagnosed with ADHD for about 5 years now.  He also suffers from anxiety, depression, and PTSD.  I didn't notice his need to be right all the time at the beginning of our relationship.  I'm not sure if I was just high on emotion and blind with love and infatuation or if he didn't exhibit this behavior as much then.  I use to be able to talk to him when he was depressed and make him feel better.  Now it seems like when he's depressed I can't say anything that makes him feel better.  I try to tell him good things about himself, but he just denies them.  He's recently watched some videos on YouTube of a Dr. Barklay on ADHD.  He's become extremely depressed and doesn't think that he can improve his ADHD symptoms or behavior.  That it's a physical deformity of the brain and that even with all the knowledge of the world on how to help his ADHD, he still won't be able to utilize this knowledge.  I'm so very frustrated.  I've worked as a paraprofessional in schools and so has my mother.  We know that ADHD symptoms can be improved.  He refuses at this point to see any positives in having ADHD.  When I try to bring up any positives, he states that those are just his personality traits that have nothing to do with ADHD.  One of the positives that I mentioned to him was the ability to think outside the box.  It's one of the reasons that I fell in love with him in the first place.  He said that I was just grasping at straws to make him feel better.

Does anyone else have a spouse with ADHD that seems to feel like they are right all the time and that you are wrong?