I am just gonna copy and paste at this point:
"There are good reasons to assess cognitive abilities for treatment planning... but a potential ADHD diagnosis is not one of them on the average. It is true that people with ADHD are a bit more likely to have certain cognitive profiles than are people without ADHD. For example, people with ADHD, on average, tend to score slightly lower on tests of working memory, processing speed, and verbal fluency than on tests of visual–spatial reasoning, fluid reasoning, and crystallized intelligence (Schwean & Saklofske, 2005). However, most people with ADHD do not have this particular profile and most people with this profile do not have ADHD. In the end, a diagnosis of ADHD cannot be ruled in by any particular cognitive profile, nor can any particular cognitive profile rule it out. If you are already confident (in either direction) about whether ADHD is the correct diagnosis, there are no cognitive test results in the world that should undermine your confidence."
I would loooove to tell patients that getting alot of psychological testing and rating scales and/or cognitive testing significantly changes their kids treatment of potential ADHD, anxiety, depression, behavior problems, and/or insert garden variety psych problem here. But I happen to have a very large N data base that says...it does not.
Can it? Yes. If you have someone really accentuate the nuances. However, most psychologists actually suck at this and most of the other beneficial and nuanced aspects of psychological testing assessments. And this is coming from a trained clinical psychologist.