Nov. 16, 1999 (Los Angeles) -- ADHD, or attention deficit hyperactivity disorder, may be more common in adolescent girls than was previously thought. It frequently goes undiagnosed because girls with ADHD are less likely to behave disruptively -- the most commonly recognizable sign of ADHD -- than boys with the disorder. This finding comes from a study in a recent issue of the Journal of the Academy of Child and Adolescent Psychiatry. The study researchers say that this is the largest and most comprehensive study of girls with ADHD to date.
"The prevalence of both conduct disorder and oppositional defiant disorder [disruptive behavior disorders] found in this sample of girls with ADHD were half of those previously reported in boys with ADHD," the researchers write. "[T]he lower rates of these disorders in girls may lead to the under-recognition of ADHD in girls and may account for the marked gender differences frequently reported in clinical samples of children with ADHD."
"Because ADHD is not as visible in girls as it is in boys, it is less likely to be identified and treated," researcher Joseph Biederman, MD, tells WebMD. "This may account for the discrepancy in the diagnosis and treatment of girls." The other major signs and symptoms of ADHD -- impulsivity, hyperactivity, and difficulty paying attention -- are similar in both sexes, he says.
Biederman is a professor of psychiatry at Harvard Medical School. He and his colleagues studied girls ranging in age from 6 to 18 -- 140 with ADHD and 122 who did not have ADHD as a comparison ("control") group. The girls in both groups were screened by "raters" specially trained to evaluate signs and symptoms of ADHD and any co-existing similar disorders, which were much more common in girls with ADHD than in the controls. Forty-five percent of the girls with ADHD had one or more co-existing disorders, which included disruptive behavior disorders, mood disorders, anxiety disorders, and substance abuse. Girls with ADHD also scored lower on tests of academic achievement and intellectual functioning. In particular, Biederman tells WebMD that he was surprised by the high level of substance abuse found among girls with ADHD, often by age 11.
"Published studies state that girls don't have ADHD as much, but that's because the core symptom was defined as behavior disorder," says psychiatrist Lee H. Haller, MD, who was not involved in the study. "If we redefine the core problem as inattention, then one tends to look in other places -- that is, to look for it in girls as well as boys." Haller, who practices in Potomac, Md., tells WebMD, "Girls are probably being diagnosed more often now because we're more likely to think of it."
"Collectively, we need to do a better job of educating families and schools in recognizing the signs and symptoms of ADHD to help girls and boys get the help they need," says David Fassler, MD, chair of the Council on Children, Adolescents, and Their Families of the American Psychiatric Association. "Girls who are referred for learning disabilities or depression may in fact turn out to have ADHD."
Fassler, who also was not involved in the study, tells WebMD that the most important lesson for doctors in diagnosing children who may have ADHD is to "take the time to get a careful history and do a comprehensive evaluation. Each child needs an individual evaluation, which often requires more than one session. You need developmental, medical, family, and academic histories, and you can't do that in a 7-minute office visit." If necessary, he adds, a doctor should ask a colleague or a specialist for a consultation. Above all, Fassler says, "We can help our patients best by resisting the pressure to practice cookbook medicine."