My DS11 was recently diagnosed with ADHD-inattentive. Our neuropsych. did not use the IVA+Plus.
The evaluation included: a behavioral rating survey (Connor's), history (as described by us), WISC-IV, WIAT, and certain sub-tests of the NEPSY (attention, inhibition, executive function, visual-motor, and a few others). From what I understand (but maybe I'm wrong), there is not one test that can diagnose ADHD, and the diagnosis is based on a whole combination of factors.
I'm not familiar with the IVA+Plus, but it sounds maybe a bit similar to the attention/inhibition parts of the NEPSY (although the NEPSY isn't done on a computer).
Has your DS had other testing besides the IVA+plus? If you do have concerns about behavior or attention, you might want to consider a full evaluation by a neuropsychologist.
