The answer to this question is yes.  Imagine you have hundreds of ideas and thoughts going through your head at one time and are unable to focus on the 1 menial task you have been assigned to do.  You are getting feedback from teachers, co-works, other students, your boss, etc... I am sure you get my drift.  It is not acceptable to run away, scream, yell, cuss, or other socially unacceptable outbursts so you start stuffing these feelings.  If there is never a safe outlet these things continue to pile up and mood is affected - thus, you have a depressed family member with ADHD or a family member who is so high strung because of all the things going through their head they become anxious.   It is similar to a physical illness.  If one has the flu the result can be nausea, vomitting, chills, fever, diarreha, coughing, sneezing, body aches, etc.  The list goes on and thank the Good Lord the flu passes through and we go with life.  ADD/ADHD is a life long condition that and individual as they become adults are able to live without medications by finding a field of work that welcomes their creativity, hyperactivity, and other aspects of the mental health condition.