Sometimes (but not in all) I think symptoms can be taken care of by changes in diet. My six year old will not focus at times and would probably seem like he has ADD, but those are the times we know he has had too many carbs or sugar and needs more protein.
My son had a major allergic reaction to artificial colors. His symptoms were exactly like those kids allegedly diagnosed with ADD. I didn't feed him sugary, color-laden cereals, candy, soda, etc and he was just fine. I always knew when his friends gave him Skittles or some such garbage...he was near impossible to deal with for a 24 hour period...he was so hyped up.
There are way more colors in food products...especially for kids...than when I was growing up. Yeah, there were candies and bakery items with them back then, but the concentration and brightness (ie: amount used) is incredible in most kids...and adults diets these days.
Oh, my son is now eighteen-years-old and occassionally partakes of a soda...piece of candy, etc...but for the most part, is uninterested in that stuff...he loves fruit...which is expensive, but not nearly as expensive as if he ate junk food as his source of nourishment.
Praise God, my husband and I stayed the course and didn't give in to our son's begging. He learned real quick, we weren't going to budge in that department. He received a little candy or colored sugar at Christmas, Easter, Halloween, and on his Birthday from us...but not the rest of those years.