If you are truly interested, these can be found with a quick search query -- I won't do that here for you.
But you will find that ADHD is one of the most widely studied psychiatric illnesses with strong neurobiological basis and well known measurable correlates, and as I mentioned, has the highest response rates to medication for a psychiatric condition. So you should have no trouble finding out more!
No, a description of ADHD features is easy to find, but not "robust metrics".
When searching specifically for metrics used in diagnosis, some choice words come up from med central:
"A challenge with diagnosing ADHD is that the characteristics associated with the disorder – such as difficulties with focusing, shifting/dividing attention, managing frustration, organization/poor time-management, working memory, and staying engaged – are common symptoms that could have a breadth of etiologies.
As noted, *more often than not*, ADHD coincides with another disorder. "
Then for narrow-band symptoms will list examples of neuropsychological measures like D-KEFS, and finding details for each of these is again like pulling teeth. But looking at the description, all of what is tested could be impacted by other issues, including instability in home life, lifestyle factors, anxiety and depression, insomnia, etc
But you will find that ADHD is one of the most widely studied psychiatric illnesses with strong neurobiological basis and well known measurable correlates, and as I mentioned, has the highest response rates to medication for a psychiatric condition. So you should have no trouble finding out more!