The findings of a study in Pediatrics suggest that tools for early autism diagnosis may need to be refined, as indicated by the examination of symptoms in children who erroneously passed a standard screening at 18 months of age.

Heterogeneous symptom expression has become an important consideration in autism research and treatment. Most recently, the onset-age criterion for diagnosis was removed from the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, given the understanding that a child’s inability to meet social demands may not always occur at the same age.

Using data collected through the Norwegian Mother and Child Cohort Study, the authors identified 68,197 cases of children who screened negative for autism at 18 months of age. The parent-reported Modified Checklist for Autism in Toddlers was used to determine diagnosis, with a score of ≥2 of 6 critical items considered the threshold for diagnosis. Additional information on autism diagnosis was obtained through the Autism Birth Cohort.

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Despite passing the initial screening, children who received a later diagnosis exhibited delays in social, communication, and motor skills compared with true-negative cases; these differences were often more pronounced in girls.

Differences across autism status and sex were examined in social, communication, fine motor, and gross motor domains, plus the categories of sociability, shyness, emotionality, and activity. All of these categories except shyness and emotionality showed a significant difference between those who received a later diagnosis and those who did not. Girls in particular exhibited a larger gap in the communication domain across groups.

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The interpretability of these findings is limited by the lack of full-scale measures of symptoms. Future studies would ideally include direct measures of verbal and nonverbal development and data on symptom severity. The authors emphasized the importance of continuing the path toward precise tools for early autism diagnosis that will enable prompt intervention.

Disclosures: Dr Hornig is a coinventor on a patent on an intestinal microbiome biomarker for autism assigned to Columbia University (US patent number 9050276) and on patent applications based on another set of proposed autism-associated biomarkers also assigned to Columbia University (US patent application number 20170328917, international Patent Cooperation Treaty application number PCT/US2013/028589, and WO2010147714A1). No funding has been received from these patents at the time of the writing of this article; the other authors have indicated they have no financial relationships relevant to this article to disclose.


Øien R, Schjølberg S, Volkmar F, et al. Clinical features of children with autism who passed 18-month screening [published online May 21, 2018]. Pediatrics. doi:10.1542/peds.2017-3596