Differentiating among children with PDD-NOS, ADHD, and those with a combined diagnosis on the basis of WISC-III profiles.

Cramm et al. (2009) looked at WISC-III scores for three groups of kids.

One group had PDD-NOS, one had ADHD, and one had both labels.

They wanted to see if the test could tell the groups apart.

The test did separate the PDD-NOS kids from the ADHD kids.

It did not support making a third “combined” box.

In short, the profiles are different enough to keep the two diagnoses apart.

Koyama et al. (2006) saw the same split earlier.

They also found PDD-NOS kids scored lower on verbal parts and higher on block design.

Kim et al. (2020) later repeated the idea with the newer WISC-IV and still found distinct patterns.

Moss et al. (2009) used a parent checklist instead of the WISC yet reached the same positive split, showing the finding holds across tools.

If you test a child who might have either PDD-NOS or ADHD, look at the WISC-III gap between verbal comprehension and visual-spatial subtests. A wide gap favors PDD-NOS. Do not create a separate “combined” profile; the data do not back it. Use this quick visual check to sharpen your referral or treatment plan.