Hi,
Many children, particularly girls, are not identified as being ADHD because of the less hyper-active, more inattentive nature. Of course the same applies to many less-hyper boys too.By adulthood most people are classified as combined type, meaning moving between the two states of ADHD, some may spend most time in inattentive but can be quite hyper in speech or when excitedl; others mainly hyper until addictions, struggles, exhaustion slow them, and then seem classic inattentive. All shades of:
hyperactive full-of-energy, positive, charismatic, trouble
inattentive procrastinating, information crazy or TV/Apps/games/books/facebook, dreamy
But underlying this all is the same ADHD neurology, a brain that is different to "average/normal" brains due in large part to a highly heritable genetic difference in how dopamine and nor-adrenaline (nor-epinephrine) are processed in the brain. I am an adult with ADHD and also an Adult ADHD Coach, if you are interested please have a look at a new video I made about what it is to be ADHD and how our particular set of negative and positive traits can affect us.
YouTube Film: The Integrated Model of ADHD (6 mins)
Once you get the basics of ADHD, about low dopamine, under stimulated minds - so more easily bored and distracted, less emotionally controlled, poor time sense (tend to be late, fail to plan and think ahead, procrastination), more maverick (a little less socially compliant, more likely to challenge authority - often for good reason!), and usually more creative, intuitive, funny, verbal, empathetic and able to see the big picture. If your child is ADHD/ADD the odds are likely that at least one parent is too as ADHD is as genetically inherited as height, so it might be a chance for one of you to get some help too.
Hope that helps
Andrew Lewis (ADHD myself, diagnosed at 42)
Adult ADHD Coach
www.SimplyWellbeing.com