In order to figure that out, we'd need to know not only the nature of these conditions, but the nature of these conditions in the animorphs universe. I mean, the mind is what the brain does (cognitive science philosophy) and yet Rachel is still a violent psychopath while in morph, Cassie is still a self righteous hypocrite, Tobias is still Emohawk and David was still a sociopath. All of these have to do with signals/chemicals in the brain and yet they maintain them in morph, so it would make sense for other brain conditions (like ADD) to still affect you in morph, even while morphing humans. However, morphing INTO people with such conditions is where it gets tricky. The best evidence we have, since they mentioned nothing of the instincts from that time the morphed humans, is from when they morph dolphins and when they morph the smart sharks. In those cases, they did mention the brains affecting their personality, so it might make sense for a special needs human brain to affect them as well.