Turns out, pretty stable. While available diagnostic tools may not be the best for very early diagnoses (<12 months), this study on over 1000 toddlers sampled from the general population found a diagnosis of ASD made at 18 months by a clinician with expertise in ASD was more stable than diagnoses of language delay or typical development. 84% of children who received an early diagnosis of ASD still qualified for that diagnosis at 3–4 years of age. Other relevant takeaways include:
The most common diagnostic transition: ASD at first visit to ASD features at last visit (i.e., children no longer met full criteria for ASD on DSM-V, but still had some characteristics of ASD)
Only 1.8% of toddlers went from an initial diagnosis of ASD to typical development
ASD was missed in almost 1/4 of first evaluations; many of these later-diagnosed children (~43%) were initially suspected to have a language delay instead
We still need more research to figure out the best treatments and courses of action, so the intervention piece is still business-as-usual; but for now we can trust that early diagnosis of ASD is not only possible, it’s pretty reliable.
Pierce, K., Gazestani, V. H., Bacon, E., Carter Barnes, C., Cha, D., Nalabolu, S., …, & Courchesne, E. (2019). Evaluation of the diagnostic stability of the early autism spectrum disorder phenotype in the general population starting at 12 months. JAMA Pediatrics. doi:10.1001/ jamapediatrics.2019.0624.