As what everyone else said, I think that many kids portray ADHD-like symptoms. The disorder is most likely overdiagnosed. Gifted kids may be bored and appear inattentive. Kids with other learning disabilities may act out in frustration. Kids who have difficult home situations may act out. Other mental disorders such as anxiety or depression may make the child appear inattentive and unfocused.

On the flip side, I read an article that said that ADHD is over-diagnosed among the general population but underdiagnosed among those who really have the disorder. In other words, the statistics may be accurate but not portray the correct fraction of the population. Does that make sense? Like out of the X amount of people who meet the criteria for ADHD, only a certain percent of them actually get diagnosed. And the bulk of the people in the general population who make up the statistic do not actually meet the criteria. It's kind of confusing. I will try to find the link to the article and post it.

http://www.psychologytoday.com/blog/...gnosed-or-both