Relationship Between Surface-Based Brain Morphometric Measures and Intelligence in Autism Spectrum Disorders: Influence of History of Language Delay.
Early language delay history predicts unique adult brain–IQ links in autism even when current scores match.
01Research in Context
What this study did
Balardin et al. (2015) scanned the brains of adults with autism. They asked who had been late to talk as kids.
They measured cortical thickness and volume. Then they looked at how these brain sizes lined up with current verbal IQ scores.
What they found
Adults with autism plus a history of language delay showed different brain–IQ links. Their parieto-occipital cortex was key.
Adults with autism but no early language delay had a pattern that looked more like typical adults. Same IQ scores, different wiring.
How this fits with other research
Kaufman et al. (2010) and Walker et al. (2013) already showed that late first words or preschool language delay forecast lower school-age IQ. Bisol moves the story forward: the shadow of early language still shapes adult brains even when IQ catches up.
Peristeri et al. (2024) tracked preschoolers for four years and saw IQ paths split wildly. Bisol gives one reason why—language history leaves a lasting cortical signature.
Kanai et al. (2017) used WAIS-III sub-tests to separate ASD from ADHD in adults. Bisol adds brain scans to the same IQ tool, showing that language history can swing the results within ASD itself.
Why it matters
When you see an adult with autism, ask about early language milestones. Two clients can earn the same verbal IQ today, yet their brains got there on different roads. This history can guide where you place cognitive demands—visual supports may help those with the parieto-occipital pattern, while verbal mediation works for the other group. Always add ‘age of first words’ to your intake form; it’s a quick flag that predicts brain–behavior links decades later.
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02At a glance
03Original abstract
Autism spectrum disorders (ASD) are a group of conditions that show abnormalities in the neuroanatomy of multiple brain regions. The variability in the development of intelligence and language among individuals on the autism spectrum has long been acknowledged, but it remains unknown whether these differences impact on the neuropathology of ASD. In this study, we aimed to compare associations between surface-based regional brain measures and general intelligence (IQ) scores in ASD individuals with and without a history of language delay. We included 64 ASD adults of normal intelligence (37 without a history of language delay and 27 with a history of language delay and 80 neurotypicals). Regions with a significant association between verbal and nonverbal IQ and measures of cortical thickness (CT), surface area, and cortical volume were first identified in the combined sample of individuals with ASD and controls. Thicker dorsal frontal and temporal cortices, and thinner lateral orbital frontal and parieto-occipital cortices were associated with greater and lower verbal IQ scores, respectively. Correlations between cortical volume and verbal IQ were observed in similar regions as revealed by the CT analysis. A significant difference between ASD individuals with and without a history of language delay in the association between CT and verbal IQ was evident in the parieto-occipital region. These results indicate that ASD subgroups defined on the basis of differential language trajectories in childhood can have different associations between verbal IQ and brain measures in adulthood despite achieving similar levels of cognitive performance.
Autism research : official journal of the International Society for Autism Research, 2015 · doi:10.1002/aur.1470