Add our understanding that ADHD is an executive function and self regulation disorder into the text. It’s not a good idea to change the name (for legal reasons), but DSM needs to explain that this is so much more than simply an attention problem.
Get rid of subtyping. The subtypes are really just variations of severity and often change as a result of normal aging. You can go through all the subtypes in the course of regular life (a hyperactive four-year-old becomes a mixed type eight-year-old becomes an inattentive 20-year).
Add sluggish cognitive tempo. This can either be a subtype of ADHD or, more likely, a separate attention disorder from ADHD.
Change or eliminate the age of onset. Ideally they would just drop the exact age and write: “onset in childhood and adolescence,” since nature simply is not this precise.
Add new items or clarifications for adults and change the threshold from six to four. The current symptoms and thresholds were based only on children and do not work well in detecting the disorder in adults.
Explain what “impairment” means. Every disorder must “produce impairment in major life activities,” but we don’t really know what that means. Impairment needs to be defined as functioning significantly below the norm. Not below your IQ, not below some high octane peer group you’re involved with, but below the norm