Lots of the behaviors of ADHD are still quite appropriate in a 6 year old. In fact I thought for a diagnosis the behaviors were supposed to persist past a certain age which I thought was 7.
puffin, the American Pediatric group (can't remember their name lol!... but basically the professional association that represents pediatricians in America) came out with a recommendation within the last few years that children can be diagnosed earlier.
To the OP, I am actually pretty much an avoid-meds person myself.. but was struck by your ds' comment that the meds helped.
One thing I feel very confident in is that as a parent, it's really important to trust your gut instinct. Seek out and listen to all the advice you can get, but also trust what your own head is telling you, because you are the expert on your child.
polarbear
