As others have mentioned, the Wisc IV cannot be administered more than once every 12 months, ideally less than once every 36 months. Additionally, the testing of very young children is generally less accurate than older kids. And, as you have observed, ADHD can also effect scores.
You mention that she is having academic difficulties and this is a good reason to have a complete neuropsychological evaluation done. If she has ADHD, it is important that the evaluator test for difficulties in the area of executive functioning (planning, sustaining attention, self monitoring, problem soloving). A full academic assessment will help you understand if she has some hidden learning disabilities that need to be addressed. And, of course the WISC will be important to understand her cognitive profile.
My son's scores vary each time he takes the WISC. (he has significant reading disabilities and ADHD). He has taken the WISC 4 times over a period of 8 years and generally his overall pattern of strengths and weaknesses persist, but his actual scores vary widely. Medication did not result in an increase in the WMI and PSI - which are the two indices most impacted by attention. However, his scores on the VCI and PRI did go up after he began taking meds - but I'm not sure if it was age or medication that caused the change.
