For a long time, most people saw ADHD — or attention deficit/hyperactivity disorder — as "a boy thing."
Yes, the occasional woman or girl got diagnosed, but this condition was mostly about hyperactive dudes misbehaving in the backs of classrooms, or guys who couldn't focus on their work for very long.
Today, that mindset has started to shift, but even now, studies report that males get diagnosed significantly more often than females — anywhere from two to sixteen times more often, depending on the study and country.
Frequently, women and girls are told they have an anxiety or mood disorder instead, and aren't diagnosed with ADHD until later in life.
This probably isn't because the disorder is way more likely in males, either.
Evidence suggests that these two groups should be about equally likely to experience symptoms.
So, what's going on? Well, some of this might happen because of misconceptions.
But it could also be because, for some reason, ADHD may present differently in different sexes.
And if you don't know what you're looking for, you could miss the symptoms entirely. Unfortunately, there are very few studies about how ADHD affects those who are intersex or who don't identify with their sex assigned at birth.
When most studies report results in males and females, they seem to be referring to people who are cisgender.
So out of necessity, that's what we'll be referring to when we say "male" and "female" in this episode. That being said, researchers have noticed some distinct differences between these two groups.
For one, surveys show that females with ADHD are more likely to also have anxiety or depression.
Additionally, other studies have found that female participants with the disorder displayed less outward aggression than males with the same diagnosis. But what's especially interesting is that the actual ADHD symptoms also seem to be different.
When most people think of this condition, they probably tend to focus on the hyperactive or impulsive symptoms — things like restlessness, fidgeting, or being disruptive.
And those are legitimate symptoms.
But they aren't the only ones. Because according to the manual doctors use to diagnose ADHD, the symptoms can be broken into two categories: one called hyperactivity impulsivity... and one called inattention.
The inattentive symptoms include things like making careless mistakes, having trouble listening, and being easily distracted or forgetful.
And you can be diagnosed with ADHD only by having these symptoms.
The hyperactive ones aren't actually required. This is important for multiple reasons.
But in this case, a big one is that a number of studies have found that males are more likely to exhibit those hyperactive symptoms, and females are more likely to display inattentive ones.
So although a common picture of ADHD is a disruptive, aggressive boy, it's possible that a girl with the disorder could be quiet and anxious instead.
Of course, it is important to note that studies about ADHD and sex or gender are still relatively uncommon.
And while a variety of research methods are used, symptoms are often either self-reported in interviews, or are reported by parents and/or physicians.
So it's always possible that results could be skewed.
There are even a few studies that found no different in symptoms between males and females — or that found that the only differences were the prevalence of anxiety or the frequency of rule-breaking behaviors.
This doesn't mean the pattern doesn't exist, though. It just means we need more study.
In the meantime, there does seem to be enough of a trend that scientists are investigating why this difference would exist.
And so far, they've found a few ideas.
One idea supported by clinical studies is that sex hormones — like hormone and estradiol, which is a type of estrogen — can affect ADHD symptoms, which would explain the different presentations.
One 2009 study even suggested that hormone could somehow affect certain neurons before birth, which could place those kids at risk of developing ADHD.
Alternatively, a handful of small studies suggest there's some kind of biological difference between males and females with the disorder — like, that they might have slightly different brain structures.
But the sample sizes in those papers were small, so it remains controversial how true that is or how much it would affect things.
On a totally different note, there's even a chance that this could be more of a social issue.
After all, females tend to show more internalizing symptoms when it comes to ADHD — including things like depression and anxiety.
And males tend show more externalizing ones, like aggression.
This could be because of something like hormones, but it could also be influenced by societal pressure and gender roles, or also, both of those things.
At least in the United States, girls are often discouraged from expressing things like anger, so that could play into all of this somehow.
Ultimately, this is something scientists will continue researching, so it's likely that we'll keep learning more about why these differences show up.
For now, though, the fact that people are starting to realize that ADHD isn't just a boy's disorder is a great start.
Mental health is complicated, and the more people understand what symptoms look like, the more likely someone is to get treatment.
If you want to learn more about ADHD, you can watch our episode about stimulants.
It seems weird that they'd be prescribed to help people with this condition, but they are.
And there are some good reasons for it.