The moderating effects of intellectual development on core symptoms of autism and PDD-NOS in toddlers and infants.
A toddler’s developmental score only slightly softens autism symptoms and doesn’t change how those symptoms show—so keep the same diagnostic lens for every child.
01Research in Context
What this study did
Matson et al. (2013) asked a simple question: does a toddler’s overall developmental level change how autism symptoms look?
They tested very young children with autism and with PDD-NOS. They gave each child a developmental score and an autism symptom score.
Then they checked if higher developmental scores changed either the number or the pattern of autism symptoms.
What they found
Kids who scored higher on developmental tests showed slightly milder autism symptoms.
The surprise: the link was weak and looked the same in both autism and PDD-NOS groups.
In short, a child’s IQ-like score nudged symptom totals down a bit, but it did not create a different symptom picture.
How this fits with other research
Reyes et al. (2019) followed preschoolers for two years and found that temperament traits in autism shift over time. Together, the two studies warn us that early scores—whether developmental or temperament—are not fixed; reassess before you credit an intervention.
Hudry et al. (2014) saw that high-risk babies who later meet autism criteria lose their early word-learning edge by 14 months. Matson et al. (2013) widen the lens: the whole developmental level, not just language, needs watching.
Knapczyk (1989) theorized that autism comes from many small brain glitches, not one big one. Matson et al. (2013) give data to match: a single IQ number cannot neatly sort symptom patterns, supporting the idea that many factors mix together.
Why it matters
Do not raise or lower your autism diagnostic cutoff just because a toddler scores high or low on a developmental test. Use the full diagnostic tool, then track change with repeated checks. When you see symptom scores drop a little, ask: is it real growth, or did this child’s higher developmental level slightly mask the symptoms today?
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Join Free →After you run a Bayley or similar test, write the developmental score in one column and the ADOS severity in another; if they don’t line up, trust the autism metric and plan intervention either way.
02At a glance
03Original abstract
Little research has been conducted on whether deficits in developmental functioning affect the range of core symptoms for autism spectrum disorders (ASD). This study represents a first attempt to determine whether developmental level has an effect on the expression of ASD symptoms in infants and toddlers. Eight hundred and fifty-three infants were evaluated with respect to the nature and extent of their ASD symptoms and developmental functioning. Young children with autism displayed a higher number of symptoms than those with PDD-NOS on all three domains of impairment (social, communication, repetitive behaviors). As expected, children without an ASD evinced far fewer symptoms than both these groups. Developmental level was not found to be a moderator for expression of ASD symptoms for the entire sample, or individual diagnostic groups. Higher developmental level was associated with lower severity of evinced ASD symptoms in the sample.
Research in developmental disabilities, 2013 · doi:10.1016/j.ridd.2012.03.031