I’m sitting alone in my flat with my laptop open, being assessed online for a condition I’m fairly sure I haven’t got.

The assessment cost £1,200, paid for by a TV production company for a documentary on the rise in ADHD – and I want to be fair about the subject.

I’d deliberately selected a consultant psychiatrist as I knew they would do the job properly, since the point was never to go hunting for some rogue clinic dishing out diagnoses.

So over the next hour-and-a-half I answered everything the psychiatrist asked me honestly.

Yes, I keep going more or less every night until half two in the morning and then fall asleep on the spot. Yes, my phone lives in my pocket and nowhere else, because otherwise I lose it multiple times a day. And yes, I’ve a dreadful sense of time, which is why every clock in my flat is deliberately set to a different time, to keep me on my toes.

At the end, I was diagnosed with ADHD, combined type – characterised by inattention, hyperactivity and impulsivity.

Even though it’s the judgment of a highly qualified professional, I don’t accept it, and I’ll explain why later.

But something else happened in that assessment I’ve thought about far more than the diagnosis itself.

Dr Max Pemberton was diagnosed with ADHD, combined type – characterised by inattention, hyperactivity and impulsivity

For the documentary, ten-year-old Mason came off his ADHD medication for a carefully monitored experiment with an independent doctor – with the agreement of his mother Shauna

Towards the end the consultant started talking about my ‘disability’.

This discussion was being filmed, and watching on was a member of the production crew who has a progressive neurological condition. We’d built the filming schedule around what he could manage – he becomes easily tired, and there’ll be more of those things as the years go on as his condition inevitably gets worse.

He was listening as I was told, on the basis of losing my phone often and staying up too late, that I was ‘disabled’ because I had ADHD.

I’ve rarely felt so uncomfortable. If ‘disability’ can be stretched to cover the two of us, then it’s stopped meaning much of anything.

I’ve been a psychiatrist for more than 20 years, and in that time I’ve watched ADHD go from a diagnosis made occasionally, after careful assessment, to one that is demanded and all too readily dispensed by healthcare professionals, driven by self-diagnosis based on social media.

A decade ago it was uncommon in children and hardly ever seen in adults: In 2015-16 some 107,000 people in England were prescribed medication for ADHD – by last year that had risen to more than 326,000.

Today around 2.5million people in England are thought to have ADHD, 741,000 of them children and young people aged five to 24 – in March alone there were more than 800,000 ‘open’ NHS referrals that may be for an ADHD assessment.

I should say something that tends to get lost the moment anyone raises any of this, which is that the people seeking these diagnoses are struggling, their suffering isn’t in doubt. What my new Channel 4 documentary asks is whether ADHD is the best explanation for it.

To answer that, I interviewed the doctors and academics who don’t accept ADHD is simply a neurodevelopmental condition needing medical treatment – they point instead to social and environmental factors fuelling the rise.

But their voices never get heard. Rather, the stock response is that this surge in diagnoses is a sign we’re ‘catching up’ after decades of underdiagnosis.

I’ve heard this from colleagues I like and respect, but it doesn’t survive five minutes’ examination of what has happened to the criteria used to diagnose ADHD.

When I interviewed Dr Iona Heath, a GP for 35 years and a former President of the Royal College of General Practitioners, she sat with the Diagnostic and Statistical Manual of Mental Disorders (DSM) – the ‘bible’ that sets out the criteria for diagnosis – and read out the list of ADHD symptoms to me.

These include: Often fails to give close attention to details; often talks excessively; often unable to play or engage in leisure activities quietly.

But as Dr Heath points out: ‘Who knows a child who will always play quietly? If you had a child who always played quietly, you would be worried about them, or you should be. I think my entire family, for several generations, could be diagnosed on the basis of this, and it makes it so clear that if you want the diagnosis of ADHD, you’ll be able to get it.’

Dr Sami Timimi, a consultant child and adolescent psychiatrist with years of experience, fastened on one criterion in particular.

‘One of the symptoms is “often squirms in their seat”. How often is “often”? What’s a unit of squirm?’ he asked.

None of this is just nit-picking about wording: When the DSM was revised in 2013, the age by which symptoms had to have appeared for an ADHD diagnosis was raised from seven to 12, and one US study of 12 to 15-year-olds found this single alteration took the prevalence rate from 7.38 per cent to 10.84 per cent.

These were the same children, behaving in exactly the same way as they always had – but they were outside the diagnosis one day, then inside it the next, purely because a DSM committee had moved a line on a page.

Dr Max interviewed the doctors and academics who don’t accept that ADHD is simply a neurodevelopmental condition needing medical treatment

Dr Sami Timimi, a consultant child and adolescent psychiatrist, questioned how 'often squirms in their seat' can be an ADHD symptom

Known as ‘diagnosis creep’, this is why I raise an eyebrow when told we’re only ‘catching up’.

The reply to such scepticism is usually that ADHD brains ‘are wired differently’ and the scans prove it.

To find out more, I went to see Professor Katya Rubia at King’s College London, a neuroscientist who has spent 30 years scanning the brains of people with ADHD and is considered a world authority in the field.

She explained that when you compare groups of people, the connections between brain regions do look less strong in those with ADHD, but that the latest studies show these differences to be very tiny – and that when you look at individual children instead of averaging across a whole group, many with the diagnosis turn out to have entirely normal brains. No scan will tell you who has the condition.

‘Because it’s not a medical condition, we don’t have a brain scan where you can say you have abnormality here, now are you ADHD,’ Professor Rubia tells me. ‘It’s a concept which is based on behaviour.’

Then she said something I’ve held onto ever since, which is that the brain is highly plastic, and behaviour and the brain are two sides of the same coin, so if you change your behaviour your brain changes with it.

This is very important, because it means the small differences we see on a scan may be a consequence of how a child has been living – rather than the cause of how they behave. And it means that when a child’s circumstances change, their brain can change, too. A tablet is not the only thing capable of altering it.

Nor, while we’re at it, is there an ADHD gene. Successive studies have identified genes associated with it but the great majority also turn up in depression, autism and schizophrenia.

Neither is there a blood test. Of course, the same is true of a lot of diagnoses – including psychiatric ones such as depression and anxiety – and I’d never argue those aren’t worth making.

But with depression and anxiety we have mostly held on to the understanding they grow out of people’s circumstances, out of bereavement and debt and loneliness and jobs that grind them down, and that treating the person means paying attention to the life they’re actually living.

Somewhere along the way we seem to have mislaid that thought where ADHD is concerned, settling instead on the idea it’s a fixed, lifelong thing a child is simply born with.

The other trouble with this vague ADHD criteria is that almost anything can be poured into them.

Anxiety leaves people restless and unable to concentrate, and so do sleep problems, grief, bullying, a chaotic home, a hearing difficulty nobody has picked up, or just being the youngest child in the school year – and every one of those can look like ADHD when you’re working down a checklist.

It’s become a catch-all, and the trouble is that once there’s a label, everybody stops looking for what’s really going on.

Having been handed the ADHD diagnosis I was eligible for medication, so for the purposes of this experiment I took it.

It was lisdexamfetamine – the same drug thousands of children swallow every morning.

Before my first dose I read the side-effects: Agitation, anxiety, low mood, irritability, tics, uneven heartbeat, raised blood pressure, weight loss, teeth grinding, blurred vision, nosebleeds, aggression, and the list goes on.

ADHD drugs are amphetamines, Class B controlled drugs in the same schedule as morphine, and there are sound reasons we warn everybody else off them.

The experience was horrible. I’d heard people say the tablets turned them into zombies and assumed they meant dopey, but it’s subtler and stranger, because what I felt was dulled, mute, compliant and withdrawn, as if somebody had turned the colour down on the television.

My thoughts came more slowly, I wasn’t interested in anything.

An hour after taking the first tablet I wandered down to the shops: As you’ll see in my documentary, a man who normally can’t stop talking stands mutely at the counter, while the poor shopkeeper tries to make conversation. I stare blankly at him. (I went back the next day to apologise for my strange behaviour.)

If I exist at about a ten, this had me down at 7.5, and those missing couple of points are what make me who I am – with just one pill.

I could see exactly how a child on this would sit still in class, get on with his work, and then tell his mum he didn’t feel like himself.

We also know far less about the long-term effects than we like to pretend.

But a 2024 study published in the journal JAMA Psychiatry found that every additional year on the medication was associated with a 4 per cent rise in the risk of cardiovascular disease, and three to five years of use came with a 72 per cent higher risk of high blood pressure.

These drugs work by revving up the same system that governs fight or flight, nudging up heart rate and blood pressure with every dose, and years of that steady pressure take their toll on the arteries.

Professor Dinesh Bhugra, past President of the Royal College of Psychiatrists, said the ‘industry around ADHD is about making money, at the cost of misery of others’

Mason was diagnosed with ADHD two years ago and put on lisdexamfetamine, and the dose has climbed from 20mg to now 40mg

Meanwhile, the assessments themselves have turned into an industry. According to the Centre for Health and the Public Interest, there is no mandatory regulation for providers of ADHD assessments and no certified national qualification or training for those carrying them out – yet NHS spending with private ADHD companies has climbed from £36million to £128million in three years, with one private equity owned provider running a 33 per cent profit margin.

Professor Dinesh Bhugra, past President of the Royal College of Psychiatrists, was blunt about where this leads: ‘The industry around ADHD is about making money, at the cost of misery of others.’

I’d add this to the worries: When somebody has handed over a substantial sum for assessment, everybody in that room knows what they’ve come for, and it takes a strong-minded clinician to send them away without an ADHD diagnosis and a prescription.

And then there’s the world we’ve built for children to grow up in.

Professor Sam Wass of the University of East London, who studies children’s attention, told me if you sit a child in front of a screen, when they come off it they’ll behave in a way entirely consistent with an ADHD diagnosis – but ten minutes in woodland measurably reduces those symptoms, partly as our brains evolved to process the shapes and patterns in nature, which they find far less tiring than a screen.

Dr Sanah Ahsan, a clinical psychologist, described our phones as attention-degrading machines stealing our focus. We’ve built an environment in which it’s hard for anybody to concentrate and feel calm, and then diagnose the children who struggle in it.

What troubles me most, though, is what we’re telling those children, because a diagnosis says the problem sits inside them, that nobody need trouble themselves about the world around them.

Dr Timimi believes we’ve replaced corporal punishment with a new way of disciplining children, which is giving them a pill, and that in some respects it’s worse, ‘because it comes with the idea that there is something lifelong inside you going on’.

Had I been assessed 30 years ago I’d have had the ADHD diagnosis without question, and I would have ended up taking the tablets, rather than developing the coping strategies I rely on every day.

Which brings me to Mason, who is ten, and in the group most likely to be medicated – boys aged ten to 14 are the largest single group of patients in England taking ADHD drugs.

Mason was diagnosed two years ago and put on lisdexamfetamine, and the dose has climbed steadily, from 20mg to now 40mg.

By the middle of the afternoon it wears off, and his mum Shauna described the change in him as a switch being flicked, at which point he becomes angry, or upset – or both.

Mason is a lovely boy, funny and bright with it, and he told me that off the tablets his brain doesn’t switch off – something he described when younger as feeling ‘all squiggly’. He also told me he doesn’t always want to take the drugs, ‘because it takes my fun-ness away’.

Shauna put the dilemma to me better than any clinician: His thoughts going at 1,000 miles an hour, but Mason still being himself – or to have him focusing better but not feeling like himself.

‘It’s horrible that a child has to pick which side to be,’ she says.

For the documentary, the family agreed to a carefully monitored experiment with an independent doctor, and for six weeks Mason came off his medication.

If the argument is that modern life is driving these symptoms, screens and games consoles had to go away into a box – sweets and ultra-processed food with them, because of the evidence linking heavily processed diets and blood sugar swings to poor concentration and irritability. In came yoga, sport and time outdoors.

Myles, his younger brother, was asked how he felt about all this and said: ‘Cross.’ Mason said: ‘I want a lawyer.'

The first week was hard going, and Shauna’s video diaries show a boy bouncing off the walls.

But then something shifted – and by week three he was calmer and much happier. ‘I finally get to be myself,’ he said.

Lewis, Shauna’s partner, had only ever known the medicated Mason, and said it was like meeting a different person, funnier and more of a character.

Dr Iona Heath, a GP for 35 years and a former President of the Royal College of General Practitioners, said she would ban the ADHD label and stop medicating these children

Then the school reports started coming home. More disruptive, more talkative, more fidgety, disengaged. Mason was also now sitting in front of work he’d managed easily and getting upset because he couldn’t do it, with SATs coming up.

I asked Mason’s teacher whether he was easier to teach on the medication, and she said he was, working silently and independently – but that off it his friendships had grown stronger, because his classmates were seeing a sillier side of him.

Then she said something I keep returning to: ‘If I’m seeing a side to him that is his true and honest and vulnerable self, does that not make it better than it being easier?’

That, for me, is the question. If a ten-year-old boy can’t manage school unless he’s on amphetamines, I’m not convinced the problem lies in his brain.

Dr Heath would go further – she’d ban the label altogether, stop medicating these children and overhaul an education system she believes is drugging an untapped reservoir of talent out of existence.

At the end of the six weeks Shauna had an agonising decision to make: Whether Mason should go back on to the drugs (you’ll have to watch to find out what she chose).

At this point I want to stress that there are people whose difficulties with attention and impulsivity are so profound they can’t function day to day, and if we want to call that ADHD, and they find the medication helps, I’d never dream of taking that away from them.

And parents like Shauna are doing their level best, forced to choose between a child who is himself and a child who can pass his exams, which is a monstrous choice to hand anybody.

For the majority, though, we’ve reached for the prescription pad because it’s quicker and easier than asking the harder questions about schools, screens, food and the sheer pace of modern life.

My hope is that anyone watching this documentary comes away not with an answer, but with permission to start asking better questions.

• The Great ADHD Myth? will air on Channel 4 on Tuesday, August 18 at 8pm