Here's from the description of weakenesses in INJ children:
These are ADD-like characteristics. It's also been noted that INJs often need a complete lack of external distractions in order to fully concentrate. That's very much the case with myself.They have short attention spans
They get bored easily with details or routine tasks
They won't put any effort into doing something that doesn't interest them
They frequently don't hear people
They ignore details
So the notion of a J person with ADD is not far-fetched. They just don't fit into the common stereotype of an ADD person. There are actually different kinds of ADD people you know.