Clinic attenders with autism or attention-deficit/hyperactivity disorder: cognitive profile at school age and its relationship to preschool indicators of language delay.
Early language delay predicts low-average IQ and distinct cognitive scatter in children later diagnosed with ASD or ADHD.
01Research in Context
What this study did
The team looked at clinic records of elementary-age children who carried either an autism or ADHD diagnosis. They gave every child the same IQ battery and noted which kids had shown early language delays before age four.
The goal was simple: see if preschool language red flags map onto a specific school-age thinking pattern.
What they found
Most pupils with ASD or ADHD scored in the low-average range on full-scale IQ even when no learning disability had been flagged. Kids who had been late to talk stood out again: they showed a unique scatter with weaker verbal and perceptual scores than their peers who started talking on time.
Early language delay turned out to be the clearest warning sign for later cognitive struggle.
How this fits with other research
Mammarella et al. (2022) extends this idea by showing that pragmatic language tests still separate ASD from ADHD in older kids, proving the language link lasts beyond preschool.
Peristeri et al. (2024) adds a time lens: autistic preschoolers follow wildly different IQ paths over four years, so the low-average scores seen here may rise or fall later.
Houwen et al. (2014) seems to disagree, reporting that ASD IQ drops as kids age. The clash disappears when you see the age ranges: the 2010 sample was only 5-8 years old, too narrow to catch the decline visible across 6-18 years in the 2014 study.
Why it matters
If a preschooler on your caseload is barely talking, treat that as a dual warning: watch for emerging ASD or ADHD and expect school-age IQ scores in the 80-90 band even without an ID label. Use this heads-up to plan language-rich ABA goals, request psycho-educational re-evaluation each year, and set parent expectations early.
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02At a glance
03Original abstract
Many studies have shown that children with autism spectrum disorders (ASD) and attention-deficit/hyperactivity disorder (ADHD) have had early indicators of language delay. The aim of the present study was to examine the cognitive profile of school age children referred to a specialist clinic for ASD, ADHD, or both, and relate this profile specifically to the age at which these children were first flagged up (or not) as suspected from language delay during the preschool years. Forty clinic children with ASD, ADHD, or the combination of the two (without clinical suspicion of learning disability) were assessed cognitively and as regards language development and language function at a mean age of 7.3 years. They were contrasted with a group of 21 children from the community who had been flagged at 2.5 years as suspected of language delay, and who had been followed up neuropsyhiatrically/neuropsychologically and in respect of language at a mean age of 7.9 years. Mean WISC-III full scale IQ was lower than population norms (in spite of the exclusion in both samples of cases with obvious learning disability) and similar across diagnostic groups (ASD and ADHD), and across settings (clinic and community). WISC-III Kaufman factor profiles separated the diagnostic groups as regards Perceptual Organisation. Early concern about language delay was a strong predictor of lower IQ and of distinguishing between "pure" cases of ASD and ADHD. School age clinic children who present with ASD and ADHD have a similar cognitive and early language development profile as do those children from the community, followed prospectively, who present with a suspicion of early preschool language delay and are shown at school age to suffer from ASD or ADHD. Concern about early language delay in the preschool age should prompt assessments (psychiatric and cognitively) for ASD and ADHD in a multidisciplinary setting much more often than is currently the case. In many cases early language delay, even in the absence of clear learning disability should be taken as a signal that - regardless of specific diagnosis - intellectual functioning might be in the low average range.
Research in developmental disabilities, 2010 · doi:10.1016/j.ridd.2009.07.012