Attention deficit hyperactivity disorder (ADHD) refers to a chronic biobehavioral disorder that initially manifests in childhood and is characterized by problems of hyperactivity, impulsivity, and/or inattention. Not all affected individuals manifest all three behavioral categories. These symptoms have been associated with difficulty in academic, emotional, and social functioning. The diagnosis is established by satisfying specific criteria, and the condition may be associated with other neurological conditions, significant behavioral problems (for example, oppositional defiant disorder), and/or developmental/learning disabilities. Therapeutic options included the use of medication, behavioral therapy, and adjustments in day-to-day lifestyle activities.ADHD is one of the more common disorders of childhood. Studies in the United States indicate that approximately 8%-10% of children satisfy the diagnostic criteria for ADHD. ADHD occurs two to four times more commonly in boys than girls (male to female ratio 4:1 for the predominantly hyperactive type versus 2:1 for the predominantly inattentive type). While previously believed to be "outgrown" by adulthood, current opinion indicates that many children will continue throughout life with symptoms that may affect both occupational and social functioning. Some medical researchers note that approximately 40%-50% of ADHD-hyperactive children will have (typically non-hyperactive) symptoms that persist into adulthood.The medical community recognizes three basic forms of the disorder:Primarily inattentive: recurrent inattentiveness and inability to maintain focus on tasks or activities. In the classroom, this may be the child who is "spacing out" and "can't stay on track."Primarily hyperactive-impulsive: Impulsive behaviors and inappropriate movement (fidgeting, inability to keep still) or restlessness are the primary problems. Unlike the inattentive ADHD-type child, this individual is more often the "class clown" or "class devil" -- either manifestation leads to recurrent disruptive problems.Combined: This is a combination of the inattentive and hyperactive-impulsive forms.The combined type of ADHD is the most common. The predominantly inattentive type is being recognized more and more, especially in girls and in adults. The predominantly hyperactive-impulsive type, without significant attention problems, is rare.We are still learning about ADHD, and experts' understanding of the disorder is still being refined. Some believe, for example, that the term "attention deficit" is misleading.They maintain that people with ADHD are actually able to pay attention too well, rather than too little, but have difficulty regulating their attention, leaving them unable to properly focus.Others have trouble ignoring irrelevant details and/or focus so intensely on specific details that they miss the bigger and broader picture.Many ADHD sufferers cannot shift gears from one thing to another when they need to, leaving them unable to focus on what needs to be done. Extreme difficulty getting a child to stop playing a video game to come to dinner is a common example.