Autism Spectrum Disorder Diagnosis Reliable in Toddlers as Young as 14 Months

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Researchers found that a toddler diagnosed with autism spectrum disorder is unlikely to test within typical levels at age 3 years.

An autism spectrum disorder (ASD) diagnosis becomes stable at 14 months and is more stable than other diagnostic categories such as language or developmental delay, according study results published in JAMA Pediatrics.

Karen Pierce, PhD, from the Department of Neurosciences, University of California, San Diego, and colleagues conducted a prospective cohort study from January 1, 2006, to December 31, 2018. Toddlers were referred from the general population through a universal screening program in primary care or community referral. These children underwent their first diagnostic evaluation between 12 and 36 months of age and were evaluated at least once more.

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Of the 1269 toddlers included in the study, 72.3% were boys. The group’s median age at first evaluation was 17.6 months, and at the final evaluation it was 36.2 months. Overall diagnostic stability for ASD was 0.84, which was higher than for any other diagnostic group. The diagnostic stability of the youngest group (12-13 months) within the larger study population was 0.50, but this increased to 0.79 by 14 months, and to 0.83 by 16 months. In the cohort, 105 toddlers (23.8%) were not initially diagnosed with ASD but were identified at a later visit.

Of those diagnosed at their first visit, 84% had a diagnosis of ASD at the final diagnosis. Of the 16% who did not, most had milder delays at their final diagnostic visit and went from ASD to ASD features. Ultimately, only 1.8% transitioned from ASD to typical development.

The possibility of diagnosing children as early as 14 months suggests that early intervention may be possible. Researchers contended that it is important to initiate treatment immediately after an initial designation of ASD, and noted that the human brain has considerable ability to resculpt and remodel, particularly in the first few years after birth. Studies that have looked at this window of opportunity during the first few years have found that toddlers with ASD and other health challenges show such positive changes as an increase in IQ of 15 points.


Pierce K, Gazestani VH, Bacon E, et al. Evaluation of the diagnostic stability of the early autism spectrum disorder phenotype in the general population starting at 12 months [published online April 29,. 2019]. JAMA Pediatr. doi:10.1001/jamapediatrics.2019.0624