Autism spectrum disorder reclassified: a second look at the 1980s Utah/UCLA Autism Epidemiologic Study.
Today’s autism rules re-label most 1980s non-ASD cases as ASD, especially when intellectual disability is present.
01Research in Context
What this study did
Researchers pulled the old Utah/UCLA autism study files from the 1980s.
They scored every child again using today’s autism rules.
The team wanted to know how many kids would now be called autistic.
What they found
Six out of ten kids once labeled “not autism” now met ASD criteria.
The newly counted children had lower IQ scores than the original group.
Old rules missed many children who also had intellectual disability.
How this fits with other research
Schaaf et al. (2015) saw the opposite pattern in Fragile X syndrome.
Tighter DSM-5 rules dropped ASD numbers by one-third in that sample.
The two studies look contrary, but both show the same core point: changing checklists reshapes who gets counted.
Feldman et al. (1999) already warned that 1980s papers rarely explained how they used their criteria.
The new count proves that warning mattered; hidden flexibility left many cases out.
Why it matters
When you read older prevalence numbers, mentally add more kids with ASD plus ID.
Screen children with intellectual disability for autism even if an old record says “no.”
One updated rule set can flip case counts by half, so always note which manual was used.
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02At a glance
03Original abstract
The purpose of the present study was to re-examine diagnostic data from a state-wide autism prevalence study (n = 489) conducted in the 1980s to investigate the impact of broader diagnostic criteria on autism spectrum disorder (ASD) case status. Sixty-four (59 %) of the 108 originally "Diagnosed Not Autistic" met the current ASD case definition. The average IQ estimate in the newly identified group (IQ = 35.58; SD = 23.01) was significantly lower than in the original group (IQ = 56.19 SD = 21.21; t = 5.75; p < .0001). Today's diagnostic criteria applied to participants ascertained in the 1980s identified more cases of autism with intellectual disability. The current analysis puts this historic work into context and highlights differences in ascertainment between epidemiological studies performed decades ago and those of today.
Journal of autism and developmental disorders, 2013 · doi:10.1007/s10803-012-1566-0