What’s behind the UK’s increase in autism diagnoses?

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Autism is a condition in a state of slow flux. In 2021, a study found a 787% rise in the number of diagnoses between 1998 and 2018 in the UK.

Increases in diagnoses have been a feature of autism for almost as long as it has been a recognised condition: 80 years ago, autism was thought to affect one in 2,500 children. That has gradually increased and now one in 36 children are believed to have autism spectrum disorder (ASD).

This exponential rise is partly due to greater awareness and deeper understanding of the condition, as well as more clinicians who can make the diagnosis. That has led to what one expert has called autism’s “ever-wider assessment boundaries – boundaries that are still moving outwards”.

Those boundaries encompass a wide range of people for whom autism would never have been considered as a possible diagnosis, especially women and girls. The consequent awareness has led to large numbers of adults seeking medical referrals to explain differences they may have been aware of since childhood.

But other factors behind the increase remain controversial, with those in the neurodiversity movement and experts undecided as to whether the increase is also due to overdiagnosis or whether more children have the condition.

The author of the 2021 study says the boundaries of diagnoses may expand further. Prof Ginny Russell, at the University of Exeter, said: “I do think it’s going to continue until maybe everyone is categorised as neurodiverse.”

Russell said while there could be an argument for there being a marginally higher proportion than previously of children with autistic traits who have low support needs, there was “no plausible reason” to support an argument that autism cases had increased substantially.

“What’s happened is that diagnoses have increased because of ever-wider assessment boundaries – boundaries that are still moving outwards,” she said. “Some go as far as to suggest that people diagnosed with autism today are united merely by not fitting their social environment.

Russell is not alone in noting the huge rise in diagnoses. “When I started in this field in the 1980s, autism was considered quite rare,” said Prof Simon Baron-Cohen, the director of the Autism Research Centre. “But there’s been a massive shift in the last couple of decades, during which the increase in diagnoses has been exponential.”

Autism is a set of conditions which contains a wide-ranging spectrum of disabilities. And there has been a 50% increase in the number of patients with an open referral for suspected autism in England in the past 12 months.

But there are those who say that even this increase is not accurate: other research suggests the total autistic population in England and Wales exceeds 1.2 million – almost double the figure of 700,000 cited by the government for the entirety of the UK. This would be the case if the rate of diagnosis matched those for under-19s across all ages, the study says.

Elizabeth O’Nions, the lead researcher of the study, said autism was still under-recognised in adults, with more than 90% of all autistic people aged over 50 in England possibly undiagnosed.

But Dr Peter Carpenter, the chair of the Neurodevelopmental Psychiatry Special Interest Group, questioned this and pointed out that adult diagnostic services did not necessarily have the expertise necessary to review the adult population against modern criteria. “We probably do not have a realistic idea of what a ‘typical autistic 50-year-old’ looks like,” he said.

There have also been changes when it comes to understanding autism among those with learning disabilities: in the 1980s, it was thought that only a quarter of those with learning disabilities had autism. Now the NHS acknowledges that it could be as high as three-quarters. “That’s an incredibly steep rise,” said Baron-Cohen.

Another increase in autism numbers is due to the removal of Asperger syndrome as a diagnosis.

A further important moment of change was the neurodiversity movement of the late 1990s, which drove through huge changes in identification, fighting stigma and redefining autism as an identity rather than a disease. All this has led to what Russell calls the “loop”.

“A rise in diagnoses loops backs to increased awareness, which impacts on how people identify themselves, which leads to a call for more assessment centres, which has led to a greater rise in diagnoses,” she said.

“As awareness and diagnoses increase, those with less severe symptoms come forward with their own stories of how autism affects them. The diagnostic criteria is widened to take these accounts onboard, which loops back again to another increase in diagnoses.”

William Mandy, a professor of neurodevelopmental conditions at University College London, believes the nebulous nature of autism is a defining feature of the condition.

He said: “What are the traits that we need to have before we are going to label someone as autistic?. That’s such an impossible question to answer that I think we should have a numerical cut-off point – maybe we should just say 2% of the population is autistic.”

The one thing that matters even more than the profound questions around autism diagnoses is the sad truth that autistic people too often do not lead happy lives.

The NHS is doing its best but there has been a 350% rise in children waiting for an autism assessment since the height of the Covid pandemic, with waiting times exceeding two years.

Child and adolescent mental health services (Camhs) are at breaking point: 80% of child mental health referrals are autism-related in some areas of the UK. Some NHS commissioners have introduced new referral criteria to try cut lists in a move that parents say puts children at risk of harm, including suicide.

This has led to some asking whether the main objective of autism research should be refocused to understand how to help autistic people lead happier lives.

Mandy said: “We are currently very focused on making a ‘yes’ or ‘no’ distinction in terms of diagnoses. But why not say, ‘Somebody has these traits. How might that be affecting their life and what we can do to help?’”

Adults awaiting an autism diagnosis face a postcode lottery in England, with some NHS centres more than twice as likely as others to give a positive assessment of the condition.

Landmark research from University College London (UCL) suggests people have an 85% chance of being diagnosed as autistic in some centres compared with a 35% chance in others.

The findings, from the Improving Adult Autism Assessment study, have not yet been peer-reviewed but have already been picked up by NHS England for further investigation.

William Mandy, a professor of neurodevelopmental conditions at UCL, who led the research across several NHS foundations in southern England, said the wide variation suggested a lack of consistency between centres. He said it raised fears that lives could be badly affected by inaccurate diagnoses and called for “radical changes” to the system.

“Our results worryingly suggest that people are being overdiagnosed in some areas and underdiagnosed in others,” said Mandy.

The study considered a range of possible reasons behind the variation. But, he said, his conclusion was that “someone could go to one well-established clinic and get one answer as to whether they’re autistic, then go to another well-established clinic and get a completely different answer despite displaying exactly the same behavioural traits”.

“The fact is that the diagnostic manuals are open to a lot of interpretation and so there is fundamentally a lack of consensus as to where the right boundaries of autism are,” he added.

Dr James Cusack, the chief executive of Autistica, the UK’s leading autism research charity, said Mandy’s results did not surprise him. “Autism diagnosis can be a wild west in terms of inconsistencies in approach,” he said. “We know of many good quality assessment centres where people aren’t getting access to proper autism diagnoses because that centre follows untested diagnostic practices, sometimes even ones they’ve developed themselves.”

Cusack suggested the research indicated people were being overdiagnosed and said that “unless something is done to regulate this, it will affect public trust in diagnoses per se”.

also said there were large regional variations in diagnoses. He pointed to research that found up to 4% of children aged 10 to 14 years old are being diagnosed in some areas, compared with 1.5% in others.

“That’s really dangerous because it means there’s no clarity in what a diagnosis is for, who it is for and how systems support the wide range of people being given a positive diagnosis,” he said.

Unlike Cusack, Mandy guesses that there is more underdiagnosis of adults than overdiagnosis. “But the key question is, ‘What level of diagnosis is correct?’ and the honest answer is nobody knows,” he said. “But the fact that there isn’t a consistent conversion rate between referrals and diagnoses is very troubling.”

Mandy said his results “show we need radical change in the way autism diagnoses are given”. He said: “Our findings worry me because this is a high-stakes assessment that is really important in affecting somebody’s identity, their access to services and funds, and their life decisions.”

The government’s 2010 autism strategy recommended the establishment of specialist, community-based, multidisciplinary teams to provide, coordinate and oversee services. However, there is no guidance around the staffing of these teams or how they should operate. As a result, a number of different models have emerged.

Bryony Beresford, a professor at the University of York, conducted the first national evaluation of specialist autism team service models in 2020. She also found a wide variation in reported rates of diagnosis, ranging from less than 50% to more than 80%.

“Each team differed in their diagnostic assessment protocols and each was unique,” she said. “In addition, unlike some diagnoses, clinical judgment is central to the autism diagnostic process and this will contribute to variation. Does this mean we can’t trust diagnoses? We just don’t yet have the evidence to say yes or no to that question.”

Dr Peter Carpenter, the chair of the Neurodevelopmental Psychiatry Special Interest Group, agreed that it was “very much in the eye of the clinician-beholder as to whether someone is diagnosed as autistic or not”.

Many are now turning to independent diagnostic assessments but the National Autistic Society (NAS) said their decisions could not necessarily be relied on either. “There are many providers out there now, some for profit and others not for profit,” said Dr Sarah Lister Brook, NAS’s clinical director. “Some are regulated – many are commissioned by the NHS to deal with NHS waiting lists – but some operate with minimal regulation or oversight so the quality is variable.”

An NHS spokesperson said: “The NHS is fully committed to supporting and improving the lives of autistic people, and published new national guidance for autism assessment services to ensure local areas can manage the 50% increase in referrals they have seen over last year while ensuring people have the support they need as they wait to be assessed.”

Maybe it’s time to change the diagnosis criteria sub divide autism according to disability.

It’s clear psychologists haven’t a clue what their doing in fact they just make the situation more absurd