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Diagnosis of Autism Spectrum Disorder After Age 5 in Children Evaluated Longitudinally Since Infancy

Research output: Contribution to journalArticle

Sally Ozonoff, Gregory S. Young, Jessica Brian, Tony Charman, Elizabeth Shephard, Abbie Solish, Lonnie Zwaigenbaum

Original languageEnglish
JournalJournal of the American Academy of Child and Adolescent Psychiatry
Early online date3 Sep 2018
Publication statusE-pub ahead of print - 3 Sep 2018


King's Authors


Objective The diagnosis of autism spectrum disorder (ASD) has been found to be remarkably stable but few studies have followed children not initially diagnosed with ASD beyond age 3 to examine late or delayed diagnoses. The current study used a prospective familial-risk design to identify children who had undergone multiple comprehensive assessments in preschool and were determined to be ASD-negative, only to meet criteria for ASD when tested in middle childhood. Method Data were pooled across three research teams studying later-born siblings of children with ASD. Fourteen children met inclusion criteria for the Late Diagnosed group and were compared to a large sample of high- and low-risk siblings from the same sites who had ASD or typical development (TD) outcomes at age 3. Results As a group, the Late Diagnosed children scored between the TD and ASD groups on most measures administered at age 3 and differed significantly from the ASD group on most measures. However, there was significant heterogeneity among the Late Diagnosed cases. Seven showed very little evidence of ASD in preschool, while seven demonstrated subtle, subthreshold symptomatology. Conclusion Some children with ASD may present with a subtle phenotype early in life or show a prolonged time course of symptom development. This emphasizes the need for screening and surveillance schedules that extend past 36 months and continued evaluation of any child who presents with atypical early development and/or high-risk status. The findings also shed light on reasons why the mean age of ASD diagnosis remains over 4 years.

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