While it is true that boys outscore girls in math and science, according to the New Hampshire Commission on the Status of Men's
First Biennal Report (2005, pdf), the gender gap in reading and writing is even higher, and girls are in the lead. The
NHCSM 2001 report (pdf) quotes Dr. Michael Gurian, author of
The Wonder of Boys, who claimed that boys in special education outnumber girls two to one, and that for ADD diagnoses, the figure jumps to six to one.
Gaub and Carlson's 1997 review suggests that girls with ADD/ADHD show fewer behavioral problems than boys with ADD/ADHD. This difference may partially explain the diagnosis rates, but only from a fairly cynical (if realistic) view of special education as a holding pen for problem students. A well-behaved but struggling student will be allowed to continue to soldier on in the regular classroom a lot longer than a disruptive but struggling student.
The behavioral differences between the special education kids in my own high school and the kids in the standard classrooms was severe, but it always felt like these kids had been given up for lost. My aunt, a special education teacher in another state, let me visit her classroom once, and I spent the next several years terrified of the students in special education. Even now, as an adult, when I recognize the same erratic, boisterous behavior in kids on the street, I cross the street to avoid them. I end up hating myself because they are almost always boys. The girls I admired in high school were tough, even violent, and I assume these girls still exist. But I never recognize them as dangerous on the street, because I automatically profile energetic young men as dangerous, and not the women.