Studies on ADHD | ADHD Information

Not sure if this is the right location to post this but my question is do any of you know any reputable studies that state European/Western Nations have a higher reported rate of ADHD? 

I'm doing a paper that involves ADHD for school and this kind of article would really help.  If you know of any please post a link here.

Thanks.

Most recent studies point to ADHD being as common in other countries as it is in western nations.

The study below challenges the theory that ADHD is an American condition.

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=15 25089

This study also draws the conclusion that ADHD is prevalent in the same rate in other countries as in the US.

http://adc.bmj.com/cgi/content/full/90/suppl_1/i10

I hope this helps.