Although ADHD may be diagnosed at any age, symptoms are usually identified in early childhood. The condition is also one of the most common neurobehavioural disorders of childhood. The disorder comes in three types: hyperactive and impulsive, inattentive, or a combination of both types.
The male to female ratio for ADHD is about 4:1, depending on which research you look at, but this may not be an accurate reflection of the true prevalence for girls. Historically, ADHD has always been more commonly diagnosed in boys, largely because girls present symptoms differently to boys. This means that many girls are misdiagnosed or underdiagnosed.
Boys often present with the following hyperactive symptoms:
- Hyperactive, disruptive behaviours (easy to pick up in a classroom)
- Physical aggression
- High levels of inattention
- Excessive talking
Girls, on the other hand, present with less "typical", inattentive ADHD symptoms, such as:
- Low self esteem
- Intellectual impairment
- Being withdrawn
- Inattentiveness or "daydreaming"
Boys ‘stand out’ more than their female peers
Real-world diagnosis of ADHD in girls and boys shows boys to far outweigh girls, and several studies have shown why this could be the case.
In a study of 2 332 twins and siblings, Anne Arnett, a clinical child psychologist at the University of Washington found that a sex difference in the severity of ADHD symptoms is valid, and that boys tended to have more extreme symptoms than girls.
“It's an actual neurobiological difference that we're seeing,” Arnett told the BBC. “It’s not clear why that’s the case, but it could be that girls have a protective effect at the genetic level,” she said. However, the true size of the difference is unclear.
In another study of 283 children, aged between seven and 12 years old, Florence Mowlem from King’s College London and colleagues looked at what differentiated both boys and girls who met the diagnostic criteria for ADHD from those children who had ADHD symptoms, but not enough to be diagnosed. Mowlem found that parents seemed to downplay the hyperactivity and impulsive symptoms in girls, while overstating them in boys.
Girls expected to be more sociable
A similar 2018 study of 19 804 Swedish twins found that girls, but not boys, were more likely to be diagnosed if they suffered from impulsivity, hyperactivity and behavioural problems. Some girls are also better at developing strategies that mask their ADHD symptoms.
“Girls are far less likely to bounce around the classroom, fighting with the teachers and their colleagues,” says Helen Read, a consultant psychiatrist and ADHD lead for a large London NHS Trust in an interview with BBC.
“A girl who did that would be so criticised by peers and other people that it is just far harder for girls to behave in that way.”
Those who do display the hyperactive symptoms are considered "rebellious" and a "wild child", Read added, and the behaviour might not be recognised by parents or teachers as being caused by ADHD, largely because girls are expected to be more sociable than boys.
And since boys can also present with purely inattentive ADHD, which is a less stereotypical symptom in their case, they are possibly being overlooked as well, which is worrying.
Moving into adulthood with undiagnosed ADHD
ADHD is usually first detected and diagnosed in childhood, and most people don’t grow out of it. Children who have been diagnosed with the condition often develop their own coping mechanisms. But that research suggests girls need to display more visible and severe symptoms before their ADHD is diagnosed, and that their symptoms are often missed, causing massive problems in adulthood.
An undiagnosed disorder that is untreated, it leaves people at a greater risk of many things, including not completing school; car accidents; and pathological gambling among others. In some studies, there is evidence that antisocial behaviours are also somewhat higher in those who go undiagnosed.
Research also suggests that girls with combined ADHD are at a higher risk of self-destructive actions as they move into adulthood, and are more likely to develop anxiety and depression later in life.
Recognising and treating ADHD from the onset is therefore critical for mitigating these risks, and to ensure positive lifestyle changes that improve symptoms in those with ADHD.