ADHD  has had many “names” and descriptions. In the earliest versions, the focus was on hyperactivity (body movement), and it was called “Hyperkinetic Impulse Disorder.” Because boys tend to be more physically active, they were more frequently diagnosed. Until the late 1970’s, the ratio of boys to girls who were diagnosed with this disorder was 6:1. Hyperactive movement generally did not consider verbal behavior – or talkativeness – as a symptom of what we now call ADHD. In 1980, “Attention Deficit Disorder” (A.D.D.) became the formal diagnosis. Many people who have attention problems but are not overactive call themselves ADD, though that is no longer technically correct. Instead, they are considered to have ADHD – Predominantly Inattentive Presentation.

Ratios in the research have gone from 6:1 in the 1970s to 3:1 in the 1990s and are moving closer to 1:1 in the 2010s. However,  ADHD is still being diagnosed 3 to 4 times more frequently in boys than in girls, and girls continue to be under-diagnosed. This may be partly because girls with ADHD tend to be less disruptive than boys, and their symptoms often reflect friendliness and engagement with their peers rather than interference with classroom routine. This and other reasons for girls being under-diagnosed suggest that girls (particularly those in elementary and middle school) might benefit from a full neuropsychological evaluation to assess attention, memory, processing, and executive-functioning skills to determine if they are displaying the symptoms of ADHD. 

Here are three reasons that ADHD is under-diagnosed in girls:

• Girls’ behavior often presents fewer problems in the classroom. Activity level is often seen as the main indicator of ADHD. Girls in elementary school tend to be less active and disruptive than boys but are often very talkative and social.
  
• ADHD symptoms may be overlooked in girls because many of the symptoms are executive-functioning difficulties. Concerns such as spaciness, working-memory issues, and problems in following directions are often not a major issue unless a child is failing academically. 
• The vast majority of the research on ADHD has been with boys. The results of these studies thereby lead to the conclusion that many of the symptoms of ADHD are those seen primarily in boys.