The autism diagnosis has become so broad that it could become meaningless, experts have warned.
In a meta-analysis published in JAMA Psychiatry, researchers in Quebec and Denmark analysed 11 previous reviews on people with autism.
Laurent Mottron, a research psychiatrist at the mental health unit of Montreal’s Rivière-des-Prairies Hospital and one of the study’s authors, said the criteria have shifted to the point where a diagnosis could become nearly meaningless.
About 30 years ago, someone would need to show strong differences in social skills, facial expression and other characteristics to receive a diagnosis of autism.
“Now you just have to be slightly diminished,” Mottron said. “This paper confirms something everybody at the clinical level knows.”
The researchers’ analysis found that the differences between the groups in five of the seven main constructs that define autism, including emotion recognition, theory of mind, planning and brain size, have decreased over time.
Globally, the number of people diagnosed with autism has risen dramatically in recent years. In the US, for instance, it has risen from less than 0.5% of the population in 1966 to more than 2%, according to figures reported by CBC.
The authors admitted it is possible there has been a true increase in the condition, but added that there could be other factors that account for their findings, such as greater public awareness and a lowered threshold for diagnosis.
Mottron argued that the criteria for a diagnosis have become trivial, including a child’s lack of friends or a dislike of haircuts or tags on clothing.