Cognitive and symptom profiles in high-functioning pervasive developmental disorder not otherwise specified and attention-deficit/hyperactivity disorder.

Koyama et al. (2006) compared two groups of bright kids. One group had high-functioning PDD-NOS. The other group had ADHD. Both groups had similar full-scale IQ scores.

The team gave each child the WISC-III IQ test. They also used the CARS-TV to rate autism traits. Then they looked for score patterns that could tell the groups apart.

The PDD-NOS group scored lower on verbal comprehension. They scored higher on block design, a visuospatial task. The ADHD group did not show this flip.

On the CARS-TV, social-communication items were more severe in the PDD-NOS group. These two clues together helped separate the diagnoses.

Cramm et al. (2009) ran a near-copy study with younger kids and found the same WISC-III pattern. Their work is a clean conceptual replication.

Kanai et al. (2017) moved the idea to adults using the WAIS-III. Again, ASD adults showed verbal dips and visuospatial peaks. This extends the finding across the lifespan.

Kim et al. (2020) updated the test to WISC-IV and still saw weaker verbal comprehension in ASD boys. The core pattern has survived test revisions.

Ng et al. (2019) sounds a warning: parent ratings and test scores can disagree. Their data do not cancel the WISC clue, but they remind you to check both sources.

You now have a quick red flag: big gap between WISC-III verbal comprehension and block design plus low social-communication CARS-TV items points toward high-functioning ASD, not ADHD. Use this pattern as one piece of your puzzle, not the whole picture. It can speed up differential diagnosis and guide your next steps, whether that is a full ADOS or an ADHD rating scale.