Researchers at Harvard Medical School (Joseph Beiderman, M.D. et al.) recently reported on the largest and most comprehensive study of girls with attention-deficit hyperactivity disorder (ADHD). Previous research has been based almost exclusively on male subjects, and these researchers believe that girls with ADHD may be underidentified and undertreated. They sought to identify characteristics and behavior related to ADHD in girls and compare it to what is known about boys with ADHD.
A meta-analysis of previous research on ADHD suggests that, compared with boys, girls with ADHD tend to have greater intellectual impairments, lower levels of hyperactivity, lower rates of conduct disorder, and higher rates of mood and anxiety disorders.
Beiderman and colleagues identified 140 girls from 6 to 18 years of age who were diagnosed with ADHD. They were compared to 122 girls without ADHD. No ethnic or racial groups were excluded, but a large majority of the girls in both groups were white. Potential subjects were excluded if they had been adopted or if their family was not available for study. Girls with major sensorimotor handicaps, psychosis, autism, inadequate command of the English language or an I.Q. below 80 were also excluded.
All the girls were referred by either pediatricians or child psychiatrists. The girls’ mothers were interviewed on tape about family background, and symptoms of ADHD and other behavior problems. Diagnostic decisions were made by a committee of child psychiatrists who were unaware of whether a child was labeled ADHD or had been treated for another disorder. I.Q and distractibility were estimated with an abbreviated form of the Wechsler Intelligence Scale for Children. Reading and math achievement were assessed with the Wide Range Achievement Test-Revised.
As expected, girls with ADHD were more likely to exhibit inattention rather than hyperactivity. Of the three types of ADHD, inattention with hyperactivity was the most common type seen in this population of girls. Inattention without hyperactivity was the second most common, while hyperactive-impulsive behavior by itself was least common.
No meaningful statistical differences in social class, family structure, or ethnicity were found between the girls with ADHD and those without. Girls with ADHD were significantly more likely than those without ADHD to have disruptive behaviors and mood, anxiety or substance-abuse disorders. Girls with ADHD also tended to have increased risk for obsessive-compulsive, panic and language disorders.
It is important to note, however, that although girls with ADHD were significantly more likely to have additional problems besides ADHD, these problems were far from universal. Fifty-five percent of the girls with ADHD had no symptoms of other disorders.
While girls with ADHD had a significant degree of impairment in intellectual functioning on I.Q. and achievement tests, they were not significantly more likely to be learning-disabled. There were higher levels of both family and school dysfunction in the ADHD population.
Girls with ADHD revealed a similar pattern of symptoms as boys with the disorder. However, girls tended to exhibit more inattentive behavior compared to more hyperactive-impulsive behavior in boys, and more mood and anxiety disorders rather than the disruptive behavior disorders seen in boys.
Although girls with ADHD had significantly higher rates of disruptive and oppositional-defiant disorders than did non-ADHD girls, these rates were half those found in boys with ADHD. These findings confirmed previous research. However, this study by Beiderman et al. documents that ADHD in girls is a serious disorder associated with impairment in several domains.
The rate of occurrence and level of dysfunction associated with mood and anxiety disorders indicates the need for careful evaluation and treatment of all children with ADHD. The treatment of ADHD is more complicated in children with multiple problems and such children often do not respond to stimulant drugs.
In contrast to previous findings with boys, girls with ADHD were at significantly greater risk for substance abuse (alcohol, tobacco and other drugs).
Despite severe symptoms, girls are less likely to be referred for ADHD, probably because they are less disruptive than boys. Because girls are more likely to show symptoms of mood and anxiety disorder, they may be diagnosed with depression but not ADHD. This is especially true for girls with the inattentive type of ADHD. This research suggests that girls referred for other problems should be evaluated for ADHD as well.
Limitations and Conclusions
This study was limited in several ways. Since nearly all the girls were white, studies of minority populations should be conducted. In addition, replication studies are needed to determine whether the pattern of findings observed here is found in other samples of children.
Also, there may have been some bias in the mothers’ reports. Previous research has demonstrated that when a child has one illness, parents tend to report a second illness. This may have led to an overestimation of the occurrence of other disorders with ADHD.
Despite these considerations, this study has shown that with the exception of the low incidence of disruptive behavior, the picture of female ADHD is very similar to that found in males. It is characterized by high levels of coexisting mood and anxiety disorders as well as significant impairments in cognitive,
“Clinical Correlates of ADHD in Females: Findings from a Large Group of Girls Ascertained from Pediatric and Psychiatric Referral Sources” Journal of the American Academy of Child and Adolescent Psychiatry, Volume 38, Number 8, August 1999, pp. 966-975.
Published in ERN October 1999 Volume 12 Number 7