MELBOURNE: Autism has become a “catch-all diagnosis” that is applied to so many people that it risks being almost useless, one of Britain’s leading experts on the condition has warned.
Every case of autism now falls under a single clinical label: autism spectrum disorder (ASD). However, Professor Dame Uta Frith said the diagnosis is being applied to individuals whose lives and needs bear little resemblance to one another, from children with profound disabilities who require lifelong care to adults with subtle symptoms who live independently.
Writing in the journal Psychological Medicine, she called for the spectrum to be split into clearer groups. This could prevent misdiagnoses while ending the “tragic neglect” of those with the most severe disabilities, she argues.
“Autism wasn’t always defined this way — a sort of catch-all diagnosis for a huge variety of conditions,” she said. “When it was first identified in the 1940s, it referred to a small group of children with severe difficulties in social interaction, communication and behaviour. Over time, the definition has widened to include people with milder traits and no language or learning problems.”
She added: “In the past, my colleagues and I felt confident that we could recognise autism at first impression. But this would not be true today.”
Frith is the emeritus professor of cognitive development at University College London. Her work helped to establish influential theories about how autistic people understand the minds of others and how they process detail and context.
The number of people being diagnosed with autism has soared, though figures from different periods are not directly comparable because the criteria have changed dramatically. A British study, published in 1966, identified about four autistic children in every 10,000. Recent research has put the proportion of schoolchildren with a recorded diagnosis at about one in 57 — a 44-fold increase.
A separate study of UK primary-care records found a nearly ninefold increase in the rate of newly recorded cases between 1998 and 2018. This does not mean autism itself increased at the same rate. Greater awareness of the condition, less stigma and better recognition of autism in women and adults are likely to explain much of the rise, researchers say.
According to Frith, efforts to recognise people who were once overlooked may also be pulling too many different problems under a single diagnosis. “Has the desire for inclusiveness eventually led to overinclusion?” she asked.
Frith has recently highlighted evidence of marked differences between people diagnosed in childhood and those identified in adolescence or adulthood. Those diagnosed as children are more likely to have obvious developmental, language or learning difficulties. Those diagnosed later are more likely to have average or high intelligence and conditions such as anxiety, depression, post-traumatic stress disorder or attention deficit hyperactivity disorder.
Some research has also found differences in the genetic patterns linked to the two groups. Frith argues that they may be so distinct that “we can no longer see a common denominator”.
There is no blood test, scan or other biological marker that can confirm autism. Diagnosis depends on a patient’s history, their words and the observations and judgements of clinical staff.
Frith added that she was concerned about “masking”, which refers to the idea that some people conceal their autistic traits to fit in. She accepts that this may explain why some cases were previously missed, but warns that the concept could mean, in theory, that somebody could be diagnosed as autistic without having any symptoms whatsoever.
“If masking can be used to explain the total absence of symptoms,” she wrote, “then, in theory, this could lower the diagnostic threshold to zero.”
An incorrect diagnosis can shape a person’s identity and treatment, she added, and may become “a self-fulfilling prophecy” that is difficult to reverse. It can also divert attention from the true cause of someone’s distress.