I don't have any problem with the doctors, but I have had a few of them that just will not learn a new task. At first I thought it was maybe because I waited until the villager was in their 40's. So I thought, while they are young, get them to an adept stage then switch them to something else. Make sense? But I have still had a few of them that everytime I take my eye off of them they go right back to their original job! I finally give up on that villager and just let them continue on with what they like and move on to a different one.

So yes, I think some of them may be a little bit "mentally challenged." LOL!