The misnomer of 'high functioning autism': Intelligence is an imprecise predictor of functional abilities at diagnosis.
IQ alone cannot tell you if a child with autism can dress, talk, or make friends—test adaptive skills every time.
01Research in Context
What this study did
The team looked at kids newly diagnosed with autism. They compared each child’s IQ score with the same child’s Vineland adaptive score. They wanted to see if a ‘high’ IQ meant strong daily living skills.
The study covered a wide age range. It included children who had no intellectual disability.
What they found
IQ was a poor guess of real-world skills. Even children with average or high IQ scores showed big gaps on the Vineland. The gap stayed wide as kids got older.
The label ‘high functioning autism’ did not hold up. A smart test score did not equal dressing, talking, or eating skills.
How this fits with other research
Symons et al. (2005) once claimed that short Wechsler IQ forms work great in ‘high-functioning’ autism. Mulder et al. (2020) now show those same IQ scores fail to track daily skills. The two papers seem to clash, but they measure different things: one looks at test–test accuracy, the other at test–life accuracy.
Courchesne et al. (2019) offer a fix. They showed that strength-based cognitive tests raise cooperation and give a truer picture in minimally verbal preschoolers. Using their method early could shrink the IQ-adaptive gap before it widens.
Mottron (2004) warned that quick screens like PPVT overestimate IQ. Mulder et al. (2020) broaden that warning: any IQ label, even from a full Wechsler, can overpromise daily independence.
Why it matters
Stop writing ‘high functioning’ in your reports. Always pair IQ testing with Vineland or ABAS. Write separate goals for cognitive and adaptive growth. This habit keeps families, schools, and payers focused on skills that matter for real life.
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02At a glance
03Original abstract
'High functioning autism' is a term often used for individuals with autism spectrum disorder without an intellectual disability. Over time, this term has become synonymous with expectations of greater functional skills and better long-term outcomes, despite contradictory clinical observations. This study investigated the relationship between adaptive behaviour, cognitive estimates (intelligence quotient) and age at diagnosis in autism spectrum disorder. Participants (n = 2225, 1-18 years of age) were notified at diagnosis to a prospective register and grouped by presence (n = 1041) or absence (n = 1184) of intellectual disability. Functional abilities were reported using the Vineland Adaptive Behaviour Scales. Regression models suggested that intelligence quotient was a weak predictor of Vineland Adaptive Behaviour Scales after controlling for sex. Whereas the intellectual disability group's adaptive behaviour estimates were close to reported intelligence quotients, Vineland Adaptive Behaviour Scales scores fell significantly below intelligence quotients for children without intellectual disability. The gap between intelligence quotient and Vineland Adaptive Behaviour Scales scores remained large with increasing age at diagnosis for all children. These data indicate that estimates from intelligence quotient alone are an imprecise proxy for functional abilities when diagnosing autism spectrum disorder, particularly for those without intellectual disability. We argue that 'high functioning autism' is an inaccurate clinical descriptor when based solely on intelligence quotient demarcations and this term should be abandoned in research and clinical practice.
Autism : the international journal of research and practice, 2020 · doi:10.1177/1362361319852831