How many of us will end up being diagnosed with ADHD?

Prof Emily Simonoff echoes this. She is a child and adolescent psychiatrist at the King’s Maudsley Partnership for Children and Young People. She thinks about 5 to 7% of children have ADHD in the UK – and says: “It's pretty similar across the world, that’s been consistent and it hasn’t actually risen.”

Prof Simonoff agrees that there’s been a “steep incline” in people coming forward for assessment since the pandemic – but says this comes after years of “long-term under-recognition".

She points to statistics on ADHD drugs. She would expect about 3 to 4% of children in the UK to need ADHD medication, but in reality, only 1 to 2% are actually using it. She thinks this shows that we are still underestimating the scale of the issue.

Prof Simonoff explains: “I think that's an important starting point for when we say, ‘My goodness, why are we seeing all these children now – are we over-identifying ADHD?’ We have under-diagnosed or under-recognised ADHD in the UK for many, many years.”

In other words, we can expect more people to be diagnosed with ADHD now because services are playing catch-up.

Thea Stein is chief executive of health think tank the Nuffield Trust. She’s got her own description for the recent increase in demand: “the Hump”. She says: “Diagnosis or desire to be diagnosed has risen because of knowledge and visibility – [it’s as] simple as that.”

According to Stein, the most immediate task is getting through the Hump, assessing the huge backlog of people on ADHD waiting lists. Then, in the longer-term, she thinks society will get better at spotting ADHD sooner in children. She hopes this will mean that they get better support from an early age, and take some of the pressure off adult services.

She says: “I have real optimism that we will come through this period of time to a much better place as a society. What I don't have optimism about is that this is a quick fix.”

ADHD might be a new concept, but people struggling to concentrate is an old problem.

In 1798, Scottish doctor Sir Alexander Crichton wrote about a “disease of attention” with “an unnatural degree of mental restlessness.”

He explained: “When people are affected in this manner… they say they have the fidgets.”

ADHD goes beyond problems concentrating or being hyperactive, though. People with it can struggle regulating their emotions and impulses. It’s been linked to substance abuse and financial difficulties as well as higher rates of crime and even car crashes.

All the experts I speak to firmly agree on one point: it is much better for someone with ADHD to be diagnosed and treated as early as possible.

Dr Müller-Sedgwick says there’s a “risk of really bad outcomes”. But he lights up when he describes how diagnosis and treatment can transform lives.

He says: “I have seen so many patients getting better, getting back into work or back into education. I have seen parents who were going through family court proceedings who were able to be better parents.

“That's why we work in this field, it's a really rewarding part of mental health to work in.”

Currently, ADHD treatment revolves around medication and therapy, but there are other options on the horizon.

A patch worn by children with ADHD on their foreheads during sleep – connected to a device that sends stimulating pulses into the brain – is on sale in the United States. It’s not prescribed in the UK, but academics here and in the US are working on clinical trials looking into it.

Prof Katya Rubia is a professor of cognitive neuroscience at King’s College London – as she puts it, “My work over the last 30 years or so is basically imaging ADHD, understanding what is different in the brains [of people with ADHD].”