Nearly 3 to 5 percent of American children - that means both girls and boys - are affected by attention-deficit hyperactivity disorder or ADHD. This puts the total incidence of American children suffering from ADHD at 2 million. As these children grow, ADHD's impact manifests itself on their psychological development, relationships, education and quality of life. Family members and direct caregivers are also affected since ADHD continues into adolescence and adulthood.

Extensive research into ADHD has led the American healthcare regulatory authorities to recognize ADHD as a disease, and this has led to enhance awareness among medical specialists - psychiatrists and clinicians.

Over the years, scientific evidence has shown that boys are more frequently diagnosed with ADHD than girls; the ratio stands at 3:1. Since ADHD is marked by aggressive and impulsive symptoms, girls tend to show less of this type of behavior. If a girl is diagnosed with ADHD, she is generally older. The prevalence of ADHD in male and female adults has been estimated at 4.4%.

It is interesting to note that ADHD was only fully recognized as a disease in 1994. Between 1940 and 1964, ADHD was called many different things including brain dysfunction, hyperkinetic syndrome and minimal brain dysfunction. Eight years later, in 1968, doctors named it hyperactive child syndrome, and in 1980s, it was termed attention deficit disorder with or without hyperactivity.

There is no simple test to diagnose ADHD. Diagnosis is done primarily based on a number of characteristics these children show apart from a number of symptoms they exhibit.