I did talk to an independent school psychologist and she said that the Weschler non-verbal ability test sounds inappropriate and she wouldn't use it on an ADHD kid.
Not my area of expertise, but as a parent I'd be curious to know if that view is research-based, a widely held opinion, or one professional's personal observation and experience. All may be valid, and there is room for many approaches as all children are unique individuals... as long as the test instrument is appropriate.
Short of learning from the independent psychologist why she did not favor Welscher as an IQ test for a child with ADHD, and what instrument she did prefer, a quick websearch for "welscher adhd" may yield results such as
1)
http://www.grcne.com/giftedADHD.html,
2)
http://en.wikipedia.org/wiki/Wechsler_Intelligence_Scale_for_Children which lists uses and discusses that the Welscher may not accurately Dx ADHD based on differences in scores (was that the school's intent?).
