When a journalist asks me about something, I ask about their deadline, so I know if I have time to do the question(s) justice and give a realistic timeframe for a response. It’s a golden rule not to be railroaded into talking about something when you’re not prepared. Next, research. Maybe half an hour on the library psychology databases. I’ll write a detailed answer, trying to make it hard for something to be taken out of context, and send it off.
It’s extremely common to then see a couple of sentences from the page or so of comments I make appear in the final story. So, when I was asked about the perception that ADHD is more common right now, I’m glad I kept my notes.
Most diagnoses of ADHD are made before the age of 12, and a 2023 meta-analysis of all studies looking at prevalence of ADHD in children and adolescents, published before 2020, shows that just under 8% of under-12s in these studies had an ADHD diagnosis.
The same goes for just under 6% of adolescents. There has been a bit of an increase, but that seems to be related to a change in criteria for diagnosis. Since 2013, the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) has provided a list of nine “symptoms” that can be used to identify childhood ADHD that is primarily inattentive (eg, difficulty focusing and finishing tasks, often losing things, forgetful and easily distracted), and nine identifying primarily hyperactive and/or impulsive (eg, fidgety and constantly on the go, talking excessively and can’t resist interrupting, etc). There’s also a combined type with a bit of both.
Now, before you rush off to get a script for Ritalin, most people have a bit of this going on. Qualifying for a diagnosis requires at least six of these boxes ticked, and they need to have been happening for at least six months.
Not all nations, or diagnosticians, use DSM-5. There’s also the International Classification of Diseases (up to the 11th edition, as of 2022), and the closest thing ICD-11 has is “hyperkinetic disorder”.
What “causes” ADHD? This is a multi-layered question. There’s a genetic component, which means some people are more likely to have the ADHD “switch”, but also an environmental component, meaning that the switch might get flicked for some people but not others.
But at another level, why does ADHD happen at all? Like most things, the answer may be evolutionary. If we could all focus perfectly on what we’re doing, there’s the risk of getting eaten by something that sneaks up on us.
Think of ADHD as being like a broad spotlight, while most of us have a narrow flashlight, and the spotlight is handy for foraging.
The Global Burden of Disease (GBD) study is an international one of more than 200 countries, and the 2019 data on ADHD shows that ADHD prevalence rose between 2010 and 2019. It also fell, depending on which country you look at.
Predictably, the biggest increase was in the US. Finland reported the biggest decrease and most of Northern Europe was relatively low. Why might we feel like ADHD is more common? Because it is more common in Australasia.
Male ADHD rates are about 21/2 times higher than among women, but there’s evidence that ADHD symptoms in women are associated with hormonal fluctuation. ADHD symptoms may be “stronger” when levels of oestrogen drop, such as during menstruation and also during perimenopause. Recent research shows that women with ADHD become more impulsive during the change of life.
While most diagnoses happen in childhood, ADHD often persists into adulthood, so adult diagnosis is also relatively common. Adults often develop strategies to work around it, which may explain the lower rates of adult diagnosis. Remember, it’s only a problem if it’s a problem.
