In 1998, the National Institutes of Mental Health agreed that attention deficit hyperactivity disorder (ADHD) is indeed a legitimate psychological condition even though its definition has not been fully defined. ADHD is a syndrome generally characterized by the following symptoms that appear before the age of seven: Inattention, Distractibility, Impulsivity, Hyperactivity. Some experts further classify ADHD into three subtypes: Behavior characterized by hyperactivity and impulsivity, but not inattention. characterized by inattention, but not by hyperactivity and impulsivity. A mixed type. There are some problems with these criteria and there are arguments for both overdiagnosis and underdiagnosis of this problem. Defining ADHD is made especially difficult because a third of cases are accompanied by learning difficulties and other neurological or emotional problems. It is likely that the term attention deficit hyperactivity disorder will eventually give way to subgroups of problems that include some of these general symptoms. [For more details, see How is attention deficit hyperactivity disorder diagnosed? below.] General Description of a Child with ADHD Studies now indicate that ADHD can be diagnosed in children by age four. Parents may notice symptoms even earlier. (One mother reported that three days after giving birth, nurses referred to her son with ADHD as "Wild Willie.") The classic ADHD symptoms of inattention, distractibility, impulsivity, and hyperactivity often do not adequately describe the child's behavior , nor do they describe what is really going on in the child's mind. Other behaviors also often coincide with classic symptoms. Some experts focus on deficits in so-called "executive functions" in the brain as the key to understanding all ADHD behaviors. Such impaired executive functions may include the following: Inability to retain information in short-term memory. Impairment of organizational and planning capabilities. Difficulty establishing and using these goals to guide behavior, such as selecting strategies and monitoring tasks. Inability to stop emotions from becoming overwhelming. Inability to switch efficiently from one mental activity to another. Hyperactivity. The term hyperactive is often confusing to those who expect to observe a child running around incessantly. A boy with ADHD playing... in the middle of a paper ...... coincides with short-term memory problems.) In one study, although children with probable ADHD were able to self-report many symptoms of ADHD, they tended to believe they had used their time wisely, contrary to what their teacher reported. Lack of adaptability. Children with ADHD have difficulty adjusting to even small changes in routine, such as getting up in the morning, putting on shoes, eating new foods, or going to bed. Any change in a situation can precipitate a loud and loud negative response. Even when they are in a good mood, they may suddenly throw a tantrum if they encounter an unexpected change or frustration. In one experiment, children with ADHD were able to tightly anchor their attention when directly directed to a specific location, but had difficulty shifting their attention to an alternative location. Hypersensitivity and sleep problems. Children with ADHD are often hypersensitive to sights, sounds, and touch, and complain excessively about stimuli that seem low-key or bland to others. Sleep problems usually occur well after the time most.