Attention deficit/hyperactivity disorder (ADHD) is a common, impairing neurobehavioral disorder that generally onsets in early childhood. Though ADHD is 2-3 times more prevalent in boys than girls, approximately 6% of girls are diagnosed with ADHD in childhood, which makes it one of the most prevalent psychiatric disorders in girls. A recent meta-analysis (method described below) in the journal Pediatrics looked to further understand how ADHD manifests in girls as opposed to boys, as well as some of the later risks that come along with being a female diagnosed with ADHD in childhood.
Meta-analyses attempt to summarize a body of research. In this approach, researchers conduct an extensive search on a particular subject, attempting to find every scientific article written on the subject, including those who have not yet been published. Many studies will be excluded from the analysis for a variety of reasons (not enough information from authors, does not meet recruitment criteria, etc.), which can be helpful, since analyzing 300+ studies is very time-consuming and difficult. Once the researchers have narrowed the studies down to those that will be used in the project, they generally conduct an analysis using all of those studies in order to estimate odds ratios, which help combine the studies into an analysis that collectively summarizes the findings.

In this meta-analysis, the authors found that girls with ADHD were 5.6 times more likely to be diagnosed with oppositional-defiant disorder (ODD), >9 times more likely to be diagnosed with conduct disorder (CD), 3.7 times more likely to be diagnosed with an anxiety disorder, and >4 times more likely to be diagnosed with depression, than girls without ADHD. You might be surprised to learn that girls with ADHD were more likely to be diagnosed with what are called “externalizing disorders” (more behavioral, causes distress to others; such as ODD and CD) compared to “internalizing disorders” (causes distress within a person, such as anxiety and depression). However, because the rate of internalizing disorders is overall generally higher in girls relative to boys, the rates are lower for girls with ADHD when compared to girls without ADHD.

This study is important because it attempts to clear up questions of comorbid (simultaneously present) disorders with ADHD specifically in females, which is unique as many studies focus primarily on boys or mixed-groups with ADHD. Compared with girls with ADHD only, girls with ADHD and comorbid ODD and/or CD symptoms have particularly poor health and behavioral outcomes, such as risky sexual behaviors. Thus, it is important to assess for these externalizing problems early on, to provide the best chance for effective intervention and positive outcomes. Additionally, because of the perception that girls with ADHD exhibit fewer behavior problems than boys, girls who are referred to clinics for ADHD are often treated for their internalizing symptoms (such as anxiety and depression), even when externalizing symptoms are also evident. Therefore, an additional implication of the study is that health providers must treat externalizing problems in addition to internalizing problems when both are present. This study provides some much-needed information on risk for other forms of psychopathology in girls with ADHD.

Article reference: Tung, I., Li, J.J., Meza, J.I., Jezior, K.L., Kianmahd, J.S.V., Hentschel, P.G., O’Neil, P.M., Lee, S.S. (2016). Patterns of comorbidity among girls with ADHD: A meta-analysis. Pediatrics, 138(4), 1-13. doi: 10.1542/peds.2016-0430