Over-diagnosis ‘could mean we are all classed as being autistic’

AUTISM is now so over-diagnosed that within 10 years there will be no separation between someone with the condition and the average non-autistic person, experts have warned.

Rates of autism are rising, with between 1 and 2 per cent of Western populations diagnosed with the disorder. One in 100 Britons is now considered to be autistic, an estimated 20-fold increase from the Sixties, and some scientists are investigating whether the rigours of modern life are to blame.

But a new study by the universities of Montreal, in Canada, and Copenhagen, in Denmark, has found that the bar for diagnosing autism has become progressively lower in the past 50 years.

If the trend continues, those with the condition will become indistinguishable from people without it by 2029, the researchers estimate.

Prof Laurent Mottron, of the University of Montreal’s department of psychiatry, said: “If this trend holds, the objective difference between people with autism and the general population will disappear in less than 10 years.

“The definition of autism may get too blurry to be meaningful – trivialising the condition – because we are applying the diagnosis to people whose differences from the general population are less pronounced.”

The study looked at the diagnostic criteria for 23,000 French, Canadian and Danish people with autism from 1966 to 2019.

A diagnosis of autism is based on a series of psychological and neurological tests that look at how well someone can recognise emotions and intentions, their ability to shift from one task to another, activity planning, inhibition, brain volume and their responses to sensory stimulation.

However, the team found that in recent decades the measurable difference between people with and without autism had fallen by as much as 80 per cent. Although the diagnostic criteria remained the same, the way they were interpreted by clinicians has changed, the study discovered.

“Fifty years ago, one sign of autism was a lack of apparent interest in others,” added Prof Mottron

“Nowadays, it’s simply having fewer friends than others. Interest in others can be measured in various ways, such as making eye contact. But shyness, not autism, can prevent some people from looking at others.

“Autism is a natural category at one end of the socialisation continuum. And we need to focus on this extreme if we want to make progress.”

Over-diagnosis also leads to people being included in studies for new drugs and therapies when they do not have the condition, the authors warn.

The research was published in the journal Jama Psychiatry.