A new report by the Centers for Disease Control explains, at least partly, why the numbers of children being diagnosed with ADHD have skyrocketed in recent years: many of these youngsters (1 in 5, actually) have been improperly diagnosed.
The number of children diagnosed with ADHD jumped 42% from 2004 to 2011. As of 2011, an astonishing 6.4 million tykes were diagnosed with the disorder and placed in therapy, fed powerful mind-altering drugs, or both.
Everyone has a theory about what caused the surge in ADHD – chemicals in the environment, processed sugar, and plain old paranoia. Studies have shown that chemicals like fluoride and sugar do indeed cause and/or worsen ADHD. But according to the CDC, much of the spike in ADHD diagnoses can be attributed to doctors improperly diagnosing young patients.  
Using a survey of 2,976 families, the CDC examined how children got the label of ADHD and found that the in the majority of cases, doctors used the American Academy of Pediatrics’ strict diagnostic guidelines; however, doctors failed to use these guidelines in a shockingly high number of cases.
In 18% of cases, doctors relied solely on family members’ reports, a method which is inconsistent with AAP recommendations that doctors cull information from other sources, as well, such as a teacher, piano instructor, or coach. ADHD is supposed to be diagnosed with the help of a behavior rating scale, but that was not done with one out of every 10 children given the label.
The survey also led CDC investigators to conclude that children are being diagnosed with ADHD at a younger age; half of the children were diagnosed at age 6 or below: 17.1% at age 6, 14.6% at age 5, and 16% at age 4 or younger.
A large number of children are likely being given an incorrect diagnosis of ADHD, but there may be some who legitimately suffer from the some form of the disorder and aren’t receiving help simply because they aren’t as hyperactive as others.
Thomas Brown, a psychologist at Yale University, says the fact that children are being diagnosed with ADHD at such a young age indicates to him that the data is “loaded in the direction of hyperactive kids.” He added that children that are “quiet and spacey tend to be missed at that age.” Brown said he believes these youngsters are likely being overlooked.
 Everyday Health