DSM-5, the gold standard
With no specific markers of autism yet available in a person's genes, blood or brain, diagnosis today still largely depends on clinical assessment by physicians and their assessment teams.
The standard way of doing this is by observing how a child fits the criteria for autism listed in gold-standard manuals such as the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), as well as in standardized instruments that are mapped on DSM.
These criteria are divided into two categories: one for a child's differences in social communication and interaction and another for their restricted or repetitive behaviours, actions or activities.
In the end, however, it is the clinicians, relying on years of experience, who decide whether a child gets diagnosed – and how much they fit the DSM-5 criteria can vary a lot.
To empirically test which criteria clinicians most often observed in people diagnosed with autism, the McGill and UdeM scientists ran more than 4,200 observational clinical reports from a French-speaking cohort of children with suspected autism in Montreal through an AI program for analysis.
They tailored and carried out large language modelling (LLM) approaches to predict the diagnosis decision in each case, based solely on these reports. In particular, the investigators came up with a way to identify key sentences in the reports that were most relevant in a positive diagnosis.
That then allowed them to make a direct comparison with the U.S. diagnostic criteria also accepted worldwide – with surprising results.
They found that criteria related to socialization – emotional reciprocity, nonverbal communication and developing relationships – were not highly specific to an autism diagnosis. In other words, they were not found much more in children diagnosed with autism than in those for whom a diagnosis was ruled out.
Criteria related to repetitive behaviors, highly specific interests and perception-based behaviors, however, were strongly linked to an autism diagnosis.