The overlap is in what you call "real mental health issues". People who have biological chemical levels that are way off of the norm is what I assume you mean by "real". I agree there is a difference. The problem is that our culture creates a massive amount of mental health issues: increases in depression/adhd and other issues are from people not functioning well in the constructs of societal boundaries. I have very severe ADHD, but it is only a problem when I am forced to do pedantic tasks with no direct productivity coming out, or work jobs that I can see lead to almost no change in life quality (ie, we may work building computers but if we are building them to break quickly on purpose just to make sure we have a job building computers we start to feel very trapped and rightly so). When i allow myself to sleep when I need to and work at my own pace, and on things that need or actually create something ( even services like massages or working in a restaurant where you create a joyful experience for someone is satisfying- its all of the wasteful time wasting stuff that bums me out) I am an extremely super-productive person. You are right, it is a cultural issue, and our culture is one that creates mentally unbalanced, frustrtated aggressive individuals.