Dynamic nature of toddler development makes autism diagnosis hard, researchers say

Difficulties in diagnosing toddlers with autism spectrum disorder (ASD) might be due to the dynamic nature of the disorder during child development, researchers from the Center for Autism Research (CAR) at Children’s Hospital of Philadelphia (CHOP) have found. 

Children with clinical characteristics that put them on the ‘diagnostic border’ of autism have an increased susceptibility to either gaining or losing that diagnosis at later ages, the researchers said. 

While most children diagnosed with ASD at early ages retain their diagnosis, a significant number of children have more dynamic presentations of clinical features associated with autism and may show changes as they develop, particularly around the time they are between two and three years old. 

These changes may lead a minority of children to actually lose or gain their ASD diagnosis over time. Recent studies have introduced the idea that this change in diagnosis is the result of intermediate cases of ASD, where children are neither clearly affected nor clearly unaffected.

Although the researchers have been aware of these ‘diagnostic shifts’ no prior studies have quantitatively evaluated the transition region between these ASD and non-ASD cases. In response, the CAR research team used a data-driven approach to explore the links between early diagnostic shifts in ASD and the “fuzzy nature” of the diagnostic boundary.

The study is the first of its kind to develop a concrete understanding of how each person is unique, and how some of their core attributes may change in small ways in their third year of life, senior author Dr Robert Schultz said. 

“Past studies called attention to diagnostic instability at early ages without understanding why this was happening for each child and that these changes are gradual. Children grow in a continuous manner, and we now have a principled way to measure this steady growth and how it may push these children into and out of the diagnostic category of autism,” he added. 

The findings were published online by the Journal of Child Psychology and Psychiatry and may be accessed here.