My gifted gifted adhd daughter is 13. She has taken the WISC IV (IQ) and the ACT (college aptitude exam) this year. Her ADHD depressed her working memory and processing speed scores on the IQ test which then affected her composit scores. Her full scale score was therefore a misleading indicator of her ability level. To provide a better indicator of her ability, the psychologist calculated her GAI score (General Ability Index.) The GAI compensates for the depressing effect of low processing speed scores. Thus her full scale score of 126 became a GAI score of 135, moving her from the 96th to the 99th percentile.
She took the ACT exam as part of the CTY talent search. She scored very well in her strength areas (93%tile as compared with college bound high school seniors) and in the top 10% overall score when compared with other talent search participants.
I think her scores on the IQ test and the achievement test were very compatible. So it really depends on the child and the type of ADHD he or she exhibits.
