According to a national 2016 survey on ADHD:

• 14% of boys were diagnosed with ADHD.
• 6.3% of girls were diagnosed with ADHD.

According to the CDC, boys are three times more likely than girls to be diagnosed with ADHD.

This disparity may exist due to the difference in ADHD presentation in boys and girls. Boys are more likely to be diagnosed with hyperactive-impulsive type ADHD, which is characterized by more externalized symptoms, such as fidgeting and of trouble sitting still, and show more apparent behavioral issues. Girls are more likely to be diagnosed with inattentive type ADHD, which is characterized by more internalized symptoms that often go unnoticed, and exhibit less behavioral problems.

As a result of these differences, ADHD is often under-diagnosed in girls, and research shows this can lead to more problems with their self-esteem and mental health.