Medical groups such as the American Academy of Pediatrics, the American Academy of Child and Adolescent Psychiatry, and the American Medical Association recognize ADHD as a medical disorder. "ADHD is one of the best-researched disorders in psychiatry, and the overall data on its validity are far more compelling than for most mental disorders and even many medical conditions," according to the American Medical Association Council on Scientific Affairs.

Not all children diagnosed with attention deficit hyperactivity disorder are hyperactive. The three types of ADHD are predominantly inattentive, predominantly hyperactive-impulsive, and combined, which includes traits of the first two categories. People diagnosed as “predominantly inattentive” will have problems focusing on the task at hand, become distracted easily, and have a hard time following directions Although all children may experience behavioral problems from time to time, those with ADHD will have frequent problems severe enough to impede their daily activities at school, home, or other settings.

According to a 2010 CDC estimate, parents reported the percentage of boys ages 4-17 with ADHD was 13.2%. The percentage of girls was 5.6%.

Girls with ADHD may be overlooked because they tend to be less hyperactive than boys. (One study shows girls are more likely to have the predominantly inattentive type of ADHD, less likely to have a learning disability, and less likely to have trouble in school or their spare time.) Another possibility is that the teachers, parents, and coaches who refer children for diagnosis may be more likely to look for attention or hyperactivity problems in boys than in girls.

Many children exhibit ADHD-like symptoms from time to time, such as lack of organization, inability to listen, or failure to follow instructions. But occasional behaviors don't necessarily point to ADHD.

Diagnosing ADHD requires substantial information gathering. Only a qualified health care provider can make an accurate diagnosis. For a child to be diagnosed with ADHD:

• He or she must show six of nine symptoms of inattentiveness and/or six of nine symptoms of hyperactivity/impulsivity.
• Symptoms should be present for at least six months and should be more extreme than in other children of that age.
• Impairment from symptoms must be found in at least two environments (school, home, social, etc.).
• Some of the symptoms must be present before age 7.
• Evidence of functional impairment must be clear.
• The symptoms cannot be accounted for by another mental disorder.

In 2007, 5.4 million children between ages 4 and 17 were estimated to have been diagnosed with ADHD, up from 4.4 million four years earlier. The rate rose from 7.8% to 9.5% -- a 21.8% increase -- in four years, according to the CDC. And two out of three children in that age group with a current ADHD diagnosis take medication for the disorder.

It’s a matter of terminology. For many years, attention deficit disorder (ADD) was the term used for a whole range of attention issues. In its place, the American Psychiatric Association adopted the term attention deficit hyperactivity disorder, with three subtypes. Today, “ADD” falls under one of those subtypes: predominantly inattentive. Many of the adults diagnosed with ADHD current fall into the category “ADHD, predominantly inattentive type.” Most children have the “combined” type.

Researchers continue to study the brain for clues to ADHD, but the exact cause is still unknown. More than 20 studies suggest that ADHD is inherited. Genetics and an imbalance of brain chemicals may be factors. Researchers also are studying how brain injuries, nutrition, and social environment contribute to ADHD.

About two-thirds of children with ADHD also have other conditions or illnesses, such as a learning disability, anxiety, depression, or behavioral disorders. These other conditions make it more difficult to diagnose ADHD.

Other conditions seen in ADHD children include oppositional defiance disorder, conduct disorder, and delays in learning or language development.

In 2006, researchers estimated that 4.4% of U.S. adults have ADHD. That means as many as 60 percent of ADHD children may experience symptoms as adults. Other studies have estimated the prevalence in the adult population between 1% and 6%. It seems to be a lifetime condition.

Adults with ADD/ADHD often have trouble focusing on everyday tasks and have poor organizational skills. Other symptoms include distractibility, inability to complete assignments, and poor listening skills, all of which can lead to problems in relationships and at work.

Current medications can't cure ADHD, but they can control some of the symptoms. Parents and doctors should decide together which medication is best and when the child needs medication. People respond differently to medications, and children taking ADHD medications should be watched closely.

Stimulant medications for ADHD include amphetamine drugs (Adderall, Dexedrine, Dextrostat, and Vyvanse) and methylphenidate drugs (Concerta, Daytrana, Focalin, Metatdate, Methylin, and Ritalin). Nonstimulant medications for ADHD include Intuniv, Kapvay, and Strattera.

ADHD treatment generally attempts to improve a child’s ability to function and reduce symptoms. A complex approach including medication, behavior therapy, and parent education may be the most effective.

Between 70% and 80% of children with ADHD respond positively to stimulant medication. But all stimulants do not work for all children with ADHD. Several types may need to be tried before the most effective is found.

Behavioral modification works by teaching a child new skills for interacting with others and controlling their own behavior. Scientific evidence supports the effectiveness of behavior modification along with medication.

Through education, parents, teachers, and other adults who interact with children with ADHD learn to recognize the behaviors and symptoms and how to set effective structures and establish appropriate systems of rewards and consequences.

More research shows sugar doesn’t worsen ADHD symptoms than shows it does, according to the National Institute of Mental Health.

Health experts do agree on the importance of a healthy diet. Fruits, vegetables, whole grains, and proteins like lean meat, poultry, fish, beans, and nuts are important for every child’s good health.

One small British study published in 2007 suggests that certain artificial food color additives worsened the hyperactive behavior of children. However, independent review of the study’s findings by the FDA and European Food Safety Authority concluded that there was no substantial link between the two. More research is being done on the effect of food additives such as food coloring and preservatives.

School administrators and teachers are not qualified to diagnose ADHD. If they bring problems to your attention, it may be because your child’s behavior shows similar symptoms. You should talk with a health care provider trained in the diagnosis of ADHD. A specialist can check medical and school records and gather information from parents, teachers, and other adults who know the child well.

Executive function refers to a person’s ability to plan in advance, keep track of time, apply past experience to current problems, and other similar organizational functions. Many different conditions, such as dementia, stroke, learning disabilities, drug use, or ADHD, may result in impaired executive function.