ADHD is a medical condition that is currently under intense scrutiny. Numbers of those diagnosed are rising, waiting lists are lengthening – and the benefits bill is swelling.

One aspect of the rise in ADHD that gets less attention is “masking” – the idea that people cover up symptoms such as disorganisation, fidgeting and daydreaming to cope better with school or work.

This may have contributed to a significant portion of the rise in ADHD diagnoses over the past decade, and possibly to the rise in autism too, say experts.

But some doctors and researchers are sceptical about the entire premise of masking. “It’s an unfalsifiable concept,” said Professor Uta Frith, an Emeritus Professor of Cognitive Development at University College London.

The government review into ADHD, autism and mental health conditions was ordered by Health Secretary Wes Streeting last year.

An interim report in June said there were two possible explanations behind rising diagnoses. There could be real deterioration in the UK’s mental health, or the increase might reflect changes in awareness, diagnosis and other factors.

There are certainly more incentives for people to be diagnosed with ADHD and autism or any condition now. Diagnoses may come with disability and illness benefits, for schoolchildren, university students or adults.

At school, children with an official diagnosis may get more understanding when they break rules, longer time in exams and are offered lower grades for getting into university.

Extra time in exams

“We’ve got more and more children getting extra time in exams,” said Dr Sami Timimi, a retired child psychiatrist and long-time critic of the expansion of ADHD diagnoses. “The more you hear about that as a parent, wouldn’t you want your child to get that?”

Most doctors agree that the definitions of ADHD and autism have expanded over the past few decades – what they don’t agree on is whether that’s a good or bad thing.

One problem is that, unlike with physical conditions, there is no easy way to diagnose mental health or developmental conditions.

ADHD has no blood tests or brain scans. Instead, clinicians go through questionnaires about symptoms (such as: “How often do you have problems remembering appointments or obligations? Often, sometimes, rarely,” and so on).

That’s a subjective process and can be swayed by both the clinician and the person answering. “We are in a cultural moment where diagnoses of autism and ADHD have huge meaning,” said Dr Naomi Fisher, clinical psychologist. “If a child has a diagnosis of ADHD, then [it’s seen as] not their fault they’re behaving like this.”

The idea of masking, also called social camouflaging, was first introduced for autism, in the 2013 update to the main psychiatry textbook used in the US but also highly influential in Britain, called DSM.

It was not added to the DSM description of ADHD but the concept has been widely embraced for this condition, including by many clinicians.

“What we often see in adults who haven’t been diagnosed is that they have developed this persona of perfectionism,” said Dr Mukesh Kripalani, a psychiatrist who heads private clinic the ADHD Centre. “That level of stress is enormous.”

Masking has helped to expand our entire conception of ADHD. The condition used to be seen as something that affected children – mainly boys who couldn’t sit still at school – with most growing out of it.

Now, the assumption is that it is a lifelong condition affecting both sexes. There are different types of ADHD – you can be hyperactive and impulsive, or inattentive and forgetful, or have elements of both.

As a developmental condition, it is supposed to have been present since birth, so doctors should not diagnose someone if symptoms were completely absent in childhood.

But now, people may believe they had previously been masking their symptoms by using coping strategies or because of support from parents. “You can give a diagnosis to anybody because they’ll say they didn’t have any symptoms in childhood, but they were masking,” said Dr Fisher. “Who can disprove that?”

And according to much of the advice on social media, masking can still go on in adulthood, with the upshot that supposed hallmarks of ADHD include completely opposite behaviour patterns.

For example, being late for things is a symptom, but so is being early. Being disorganised is, but so is being highly organised. “When something is unfalsifiable, science has gone out of the window,” said Dr Fisher.

Everyone “masks” to some degree, if it means doing things you’d rather not, to meet society’s expectations, she said. But others say that people with ADHD mask much more than others – so much that it leads to anxiety, stress and mental exhaustion.

This is why people with ADHD are more likely to also be diagnosed with anxiety and depression, said Dr Elena Touroni, founder of the private Chelsea Psychology clinic.

“Our understanding of the complexity of how people cope with it, and how their symptoms manifest, has evolved. So now our ability to pick up someone’s presentation is more sophisticated than it was.”

Dr Joanna Martin, an ADHD researcher at Cardiff University acknowledged the research on masking in ADHD is at an earlier stage than for autism, but that is changing, she said.

Her team is developing research questionnaires so that masking in ADHD can be better studied, to gauge how common it is and how it affects people.

“Checklists [on social media] aren’t ones that have been validated, so I would be very cautious about those sorts of things,” she said. “But just because something hasn’t been studied yet doesn’t make it not scientific.”

Until the government report comes out, it is unclear how much it will examine the definition of ADHD or whether it will focus more on the cost to the public purse.

“The focus should be on ensuring that high-quality assessments and ongoing care are consistently available, and that people are able to access the right support at the right time,” said Dr Ulrich Müller-Sedgwick, ADHD Champion at the Royal College of Psychiatrists.

The i Paper understands that the report was due to be published last month but was delayed because politicians did not want any backlash to overshadow the Labour Party annual conference this week.

Whatever it concludes, it is likely some people will be unhappy.