I didn't get diagnosed until I was in my 30's. I had just developed coping mechanisms. I was actually shocked when the shrink told me and then I told my family and friends in disbelief. Each and everyone of them looked at me and said "DUH!! I could have told you that you were severely ADD." Hope this facts/myths helps answer some of your questions Unplugme. I found it helpful when I was first diagnosed.

MYTH: ADD/ADHD is just a lack of willpower. Persons with ADD/ADHD focus well on things that interest them; they could focus on any other tasks if they really wanted to.

FACT: ADD/ADHD looks very much like a willpower problem, but it isn’t. It’s essentially a chemical problem in the management systems of the brain.

MYTH: Everybody has the symptoms of ADD/ADHD, and anyone with adequate intelligence can overcome these difficulties.

FACT: ADD/ADHD affects persons of all levels of intelligence. And although everyone sometimes has symptoms of ADD/ADHD, only those with chronic impairments from these symptoms warrant an ADD/ADHD diagnosis.

MYTH: Someone can’t have ADD/ADHD and also have depression, anxiety, or other psychiatric problems.

FACT: A person with ADD/ADHD is six times more likely to have another psychiatric or learning disorder than most other people. ADD/ADHD usually overlaps with other disorders.

MYTH: Unless you have been diagnosed with ADD/ADHD as a child, you can’t have it as an adult.

FACT: Many adults struggle all their lives with unrecognized ADD/ADHD impairments. They haven’t received help because they assumed that their chronic difficulties, like depression or anxiety, were caused by other impairments that did not respond to usual treatment.

Source: Dr. Thomas E. Brown, Attention Deficit Disorder: The Unfocused Mind in Children and Adults