Does gender have an effect on ADHD in children?

Most studies indicate that more boys than girls have ADHD. The ratio is probably 2–3:1 in school-age children. One study that researched the frequency of ADHD in school-aged children in the United States found the rate in boys was 9% compared to a rate of 3% in girls. Age seems to have an effect on the gender ratio. The male:female ratio drops in adolescence toward 1:1. In fact, some adult studies even suggest that women have ADHD more often than men. As hyperactivity lessens, the inattentive form of ADHD more commonly seen in girls may persist and equalize the ratio.

Bear in mind, however, that these study results are determined by the detection of ADHD. Gender ratios may be affected by referral practices. Among children referred to child psychiatrists or psychologists, the boy–girl ratio varies from 3:1 to 9:1, whereas in community surveys of school-age children, it is closer to 2:1. More severely or obviously affected children are probably referred to a specialist and are usually boys. It is possible, however, that ADHD goes undetected in girls more often than it does in boys. In this regard, it is important to note that boys and girls tend to have different types of ADHD. Boys more often have the hyperactive–impulsive type or the combined type, whereas girls more often have the inattentive type. Some people suggest that this difference affects the frequency with which ADHD is picked up. In other words, boys could receive diagnoses more often because they are more vocal, their problematic behavior is more obvious, and they are more troublesome for their teachers and families. Although girls tend to be affected less often than are their male peers, some studies suggest that those with diagnosed ADHD tend to be less bright and have more academic difficulties than do boys with ADHD. It is possible that very bright girls simply compensate better and their ADHD goes undetected.