Ive seen several people remark on Josh having ADD and I have to comment on this...
As a person who has adult ADHD, its honestly not something that should be joked about. I have no idea if he really has it or not, but the stigma associated with ADD and ADHD is usually framed around laziness, unintelligent, or people that can not follow through with something, and this is honestly far from the truth. People who have ADD and ADHD think and react differently than others who do not have it, and those who have it have decreased abilities in some areas while also normally having abilities significant accelerated in other areas.
Here is an interesting article someone shared with me last night on the subject
http://www.healthline.com/health/adhd/iq-adhd#2 