Photograph: Jessie Casson/Getty Images
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.
“It may soon encompass people like me, for example. I have not changed but having some borderline autistic traits, I may soon be absorbed by autism – because it is itself changing.”
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. Created in 1994, the label was officially “retired” in 2013, with the condition subsumed under the umbrella term of autism.
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.”
In short, there is no clear answer as to what autism is – or is not. Some say there never will be.
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. Compared with non-autistic people, they are about 70-80% more likely to have poor mental and physical health, experience educational under-attainment, unemployment and underemployment, victimisation, social isolation and premature mortality.
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?’”
