<p>poetgrl: Girls with ADHD are under diagnosed. It’s not uncommon for girls with the primarily in attentive variety to make it to junior year in HS without the assistance boys get. We tend to diagnose based on how it effects others and not the kid. That said, boys are probably over diagnosed. </p>
<p>This is correct. And there has been research which indicates that, with hormonal shifts that occur around menarche, inattentive-type ADHD often starts to manifest more as mixed or hyperactive. Which would explain the upswing in identification in late middle and high school (especially given the time lag between when a problem is noticed and when it is finally labelled).</p>