i would say the same would go for ADD. let your academic performance speak for itself. though... i'm from Australasia and I think it is fair to say that the norm in the USA (compared to the norm in Australasia) is to talk yourself up.

you got really terrific grades at school so we know you can get some really terrific grades at university too.

then it is a matter of persuading them that your terrific grades are likely to persist and that the low grades were an abberation that is unlikely to repeat.

(if you have trouble believing the 'unlikely to repeat' stuff i'd suggest you get your hands on some of the anti-psychiatry literature.)

if you tell them that you have ADD and that you don't know if it is likely to affect your performance then you can expect them to choose someone else who can tell them that it isn't likely to affect their performance. if you tell them that you have ADD then you can expect them to choose someone else rather than taking a risk on your mental health.

as i said, lots of people take some time off and / or have some crap grades at university for their first year or so. if you have good referee reports, score well on the GRE, and do well in your later years then they shouldn't hold it against you.

with respect to the norms on the USA they expect you to blow your own trumpet. i'd make sure you emphasise your later grades and your GRE and say something that is likely to reassure them that your early grades are a thing of the past that isn't likely to be repeated. people tend to be fairly simple creatures... personally... i'd avoid the whole issue of mental illness because the fact is that the majority of people out there think things are likely to be chronic and hence won't be willing to take a risk on someone with mental illness if there is a comperable person who doesn't have one.

you can campaign against stigma for mental illness when you are one of the top people in IBM ;-) until then... i'd keep it under your hat...