In the United States, boys are diagnosed with ADHD at significantly higher rates than girls, although the disparity has decreased. In the mid-1990s, about 9 out of every 10 diagnoses were for boys. Boys are still about twice as likely to be diagnosed.
However, at least one study outside the U.S. now shows girls not only catching up, but surpassing boys in ADHD diagnoses, for some age groups. In British Columbia, teen girls have been diagnosed at higher rates than boys for the past few years, and if we extend the study into the first decade of adulthood, the division becomes even more stark.
The latest data from the U.S. suggest diagnoses may be trending in the same direction, though not quite as quickly.
Is This About Underdiagnosis Of Girls?
A significant factor in this is presumed to be the historical failure to recognize ADHD in girls.
ADHD can present differently in girls than in boys, although this is likely less about genetics than social and societal factors. Regardless of the reasons, though, many girls with diagnosable ADHD present without some of the hyperactivity seen in boys, or perhaps with their hyperactivity looking a bit different.
A 2019 analysis published in Frontiers in Human Neuroscience found that girls tend to present with fewer hyperactivity and impulsivity symptoms than boys, but more impulsivity symptoms, and that boys tend to have more comorbidities with externalizing disorders while girls are more likely to be found with internalizing behaviors. (In other words, ADHD in girls might present with a lot of anxiety, and in boys, it might present with more aggression and noticeable behaviors.)
The same analysis also acknowledged:
“Understanding the role of gender in ADHD care has been historically hindered by methodological issues, such as involving relatively low numbers of girls in research samples, failing to control for possible gender effects, and relying solely on subjective scales which are often subjected to reporter’s bias.”
In short, the reason girls might be underdiagnosed seems to be largely because ADHD in girls hasn’t been studied much, which in turn is because it has gone so underdiagnosed. Then, of course, bias in reporting from parents and teachers, who are much more likely to notice externalized behaviors than internalized ones.
What’s The Data Showing Now?
In this newest study, published in the Journal of the American Medical Association, data from British Columbia from 2003 to 2023 were examined, and showed two consistent trends.
The first is that girls are more likely to be diagnosed in their teens or even between the ages of 19 and 29 than at younger ages, while boys are most likely to be diagnosed between the ages of 6 and 12. The second is that for teens and young adults, the gender disparity first narrowed, then, in 2020, clearly flipped.
We see similar trends of girls receiving their diagnoses later in the U.S., as well. Duke University School of Medicine’s Department of Psychiatry & Behavioral Sciences finds that boys are three times more likely to be diagnosed in childhood. The department posits that this may be because girls’ diagnoses have to wait until they advocate for themselves.
“Women are more likely than men to be diagnosed with ADHD for the first time in adulthood. This may be due to women being able to report on their own internal experiences and seek evaluation rather than relying on parents and teachers to notice difficulties and make referrals.”
What Other Factors Are Relevant?
Aside from observer bias and some differences in presentation between girls and boys, some other factors are important to note in the British Columbia study.
For one thing, the overall rates of ADHD diagnosis have also increased across age groups and genders. Another important finding is that there are two points when the graphs change visibly: 2013 and 2020.
The 2013 change has a simple explanation. The DSM-5 was released that year, and shifted diagnostic criteria and understanding of ADHD. Researchers believe the additional increase in 2020 is attributable to additional stressors and other factors during COVID-19 isolation periods. They suggest:
“The sharpest postpandemic increases occurred among female adolescents and young adults, surpassing same-aged males for the first time on record and mirroring a similar but more transient pattern reported in Finland…Pandemic-related stressors may have further intensified ADHD symptoms and facilitated the identification of previously unmet needs, with female adolescents and young adults potentially being more vulnerable to social disruptions than males.”
What’s The Takeaway For Parents?
This data emphasizes what prior data has already suggested. Girls and boys likely have ADHD at similar rates, but it is more likely to go unnoticed in girls.
It also strongly emphasizes that additional stressors can increase ADHD symptoms, potentially causing enough additional symptoms for some kids that it prompts a request for a screening, or a different outcome from a screening than might have occurred prior.
Most of all, it reminds us that parents, teachers, and other advocates for our children should make an effort to be aware not only of externalized symptoms that disrupt the home and classroom, but also of internalized symptoms that affect our kids’ mental health and well-being.
If you believe your child is showing symptoms, speak to your pediatrician and be prepared to continue advocating for support and treatment if needed!
