While some view the rise in autism diagnoses as signs of an “epidemic,” the increase may result from a broadened definition of autism, according to a new study.
Dr. Laurent Mottron, a co-author of the study and a professor of psychiatry at the University of Montreal, connected the “pretend epidemic” of autism to “the inclusion of people less and less different from non-autistics.” For the study, published this week in JAMA Psychology, Mottron and his colleagues reviewed eleven “meta-analyses” (or studies of studies) published between 1966 and 2019, comparing people with and without autism.
Combined, the studies included almost 23,000 people diagnosed with autism. The researchers were interested in examining how the “effect size” – i.e., a measure of the severity of the differences between people with and without autism – changed over time. They found that in almost every trait, including the ability to recognize emotions in other people, and brain size, the measurable differences between people with and without autism shrank by 45 to 80%.
In a press release, Mottron shared his concerns that the term “autism” may soon be rendered meaningless, if it is continually applied to people whose differences from the general population are less significant.
“The definition of autism may get too blurry to be meaningful — trivializing the condition — because we are increasingly applying the diagnosis to people whose differences from the general population are less pronounced,” Mottron said.
Mottron believes the lack of autism discoveries in the past decade might be explained by the inclusion of people with mild symptoms who aren’t sufficiently different from people without true autism. The findings also suggest that some adults or children with symptoms loosely resembling autism may be labeled as having the condition, which can lead to inundated clinics and making it more difficult for those actually in need to get help.
In an interview, Mottron noted that there is no “gold standard,” such as a blood test, to identify who has autism and who doesn’t. He added that the diagnostic criteria have not only been broadened, but more loosely applied.
“Fifty years ago, one sign of autism was a lack of apparent interest in others,” he said. “Nowadays it’s simply having fewer friends than others. Twenty years ago you would ask for a complete absence of facial expression. Now it’s less facial expression, fewer friends, less reciprocity — it’s become more and more fuzzy.”
Mottron believes it is important that health professionals clearly distinguish autistic traits from autism, adding that only about 35% of those referred to him for an assessment of autism actually have the condition.
“The cliché that you will see everywhere is, ‘oh, you have more autism because they are better recognized,’ which is absolutely wrong,” Mottron said. “It’s not that they are better recognized,” he explained, but rather that people with less significant differences from the norm are being diagnosed with autism.