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New Research May Change How We Think About the Autism Spectrum

INSAR keynote suggests brain differences correlate with cognition—not diagnosis.

Key points

  • Dr. Evdokia Anagnostou presented the results of neuroimaging studies at the International Society for Autism Research 2022 annual meeting.
  • Of note, brain differences clustered along dimensions of cognition and hyperactivity, not diagnosis.
  • These findings suggest we need to reconsider how we classify neurodivergence.

University of Toronto child neurologist Evdokia Anagnostou dropped a bombshell in her keynote Saturday at the annual meeting of the International Society of Autism Research (INSAR) in Austin, Texas, which may call into question the validity of the autism spectrum disorder (ASD) diagnosis.

What Brain Scans Tell Us About Autism Spectrum Disorder

Anagnostou and her colleagues had set out to use neuroimaging to identify brain differences unique to ASD, as compared to other neurodevelopmental differences like ADHD, OCD, and intellectual disability. And they did find that brain differences clustered into different groups—but not by diagnosis. In fact, brain scans could not distinguish children who had been diagnosed with ASD from those who had been diagnosed with ADHD or OCD.

“Dr. Anagnostou reported data from multiple papers that looked at over 3,500 children,” Dr. Alycia Halladay, Chief Science Officer at the Autism Science Foundation, explained to me. “These studies looked at multiple structural and functional features of the brain—including cortical gyrification (the way the brain folds in the cortex), connectivity of different brain regions, and the thickness of the cortical area—and found no differences based on diagnosis.”

Groupings did emerge, but they were along totally different axes. Added Halladay, “The brains themselves were more similar based on cognitive ability, hyperactivity, and adaptive behavior.” In other words, the brains of mildly affected autistic children looked much more like the brains of kids with ADHD than they did like those of severely autistic children.

Validity of the Autism Spectrum Diagnosis May Be at Stake

If replicated, these findings could have tremendous implications for our current diagnostic framework. During the question and answer period following her talk, Anagnostou described two children who both carried the diagnosis of autism; one was very mildly affected, while the other had such disordered behavior that “even their bus driver knows” he is autistic. “Should these kids have the same diagnosis?” she asked.

Right now, they do—but there has been a growing dissatisfaction among many stakeholders in the autism community with the American Psychiatric Association’s introduction of the all-encompassing ASD diagnosis in the 2013 revision of the Diagnostic and Statistical Manual (DSM-5) to replace more narrowly defined categories, including Asperger syndrome, pervasive developmental disorder not otherwise specified (PDD-NOS), and childhood disintegrative disorder.

In 2021, the Lancet Commission—a group of 32 researchers, clinicians, autistic individuals, and family members—called for the creation of a new label, “profound autism,” that would carve out those autistic individuals who also suffer from cognitive and language impairments and require round-the-clock supervision. “Anagnostou’s data converge nicely with the Lancet Commission’s proposal,” Halladay observed. “They provide biological evidence for a category that was originally defined solely by external criteria.”

At the very least. The real question is whether this work demands an even more radical re-imagining of our classification of neurodevelopmental differences. If, as Anagnostou’s data demonstrates, cognition and hyperactivity are much more correlated with brain difference than variables like social deficit that have been considered core symptoms of autism, then perhaps it’s time to scrap our current model and introduce new diagnoses based on these more salient dimensions. Aligning our diagnostic system with underlying biology is the first step in the development of targeted interventions for some of the most intractable and dangerous behaviors exhibited by the developmentally disabled, such as aggression, elopement, self-injury, and pica (the compulsion to eat inedible objects).

As Anagnostou opened her talk, “Nature doesn’t read the DSM.” But, as our understanding of the brain advances, shouldn’t the DSM reflect these divisions in nature?