Just wondering if anyone has thoughts on how ADHD affects WISC-IV (or other IQ test) results. Is it just that the Working Memory and Processing Speed are going to be lower than Verbal and Perceptual? Or does the attention issue affect all aspects of the test?

I don't have our report yet but our tester pointed out several areas where our son's ADHD impacted his test scores... more than just working memory and processing though those were impacted. I expect my report will have more specifics and I do not recall the subtests but I remember a couple had "impulsivity" issues impact as well as not being able to "transition". We have several additional diagnoses but there were specific ones where he could see the ADHD at work.

My Dd who has ADHD did the WPPSI not the WISC, so no WMI, though her WMI was high on the SB5... But she absolutely had issues in the WPPSI where she couldn't handle the boredom of the amount of easy work required at the start of a subtest before she worked up to her level, there were a couple of subtests where she was looking avidly at the content of the first few items and barely glancing or giving any thought by the time she was closer to her actual level, instead by then she was spinning her chair from side to side and looking out the window. One subtest was spoiled completely.

Comparatively on the SB5, which has routing questions to bring a child in at roughly the right level, she was much better focused because it was more consistently engaging (better tester too).

A good tester should note in their report if the child was distracted, impulsive, not well engaged with certain parts of the test.