Inattention, Distractibility, Impulsivity, Hyperactivity.
Some experts further categorize ADHD into three subtypes:
Behavior marked by hyperactivity and impulsivity, but not inattentiveness.
Behavior that is marked by inattentiveness, but not hyperactivity and impulsivity.
A mixed type.
There are some issues with these criteria, and arguments exist for both an over- and underdiagnosis of this problem. Defining ADHD is made particularly difficult because one-third of the cases are accompanied by learning disabilities and other neurologic 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 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 delivery, nurses were referring to her ADHD son as "Wild Willie.") The classic ADHD symptoms, inattention, distractibility, impulsivity, and hyperactivity often do not adequately describe the child's behavior, nor do they describe what is actually happening in the child's mind. Other behaviors also often coincide with the classic symptoms.
Some experts are focusing 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 hold information in short-term memory.
Impaired organization and...