Hi Healing Soul,
I like your posting name. Assessing ADHD in adults is hard because the DSM criteria for ADHD is really written for children. It's a bit difficult to get a good history, because some of the information the adult may not know, but the parents do. So a good assessment will include gathering information from the client, and from those who know the client very well, such as parents. There are specific structured interviews and rating scales that are reasonably reliable and valid in diagnosing ADHD in adults. Also, it's important to rule out other diagnoses, such as depression, anxiety, or OCD, as they often have overlap in symptoms. For this the tester might use a personality test such as the MMPI and also ask interview questions. Finally, some testers do use intelligence and/or achievement tests. There is also a computerized test of attention and concentration that some use.

The most important thing for the client to be assured of is that the tester is experienced in assessing ADHD, that they gather information via a variety of methods and sources, and that they use methods that are valid for assessing ADHD in adults.

Hope this helps, and please feel free to ask other questions. I am just starting to do ADHD assessment on my internship.

gg