Who is affected by attention-deficit/hyperactivity disorder?Įstimates suggest that about 4% to 12% of children have ADHD. Brain imaging studies using PET scanners (positron emission tomography a form of brain imaging that makes it possible to observe the human brain at work) show that brain metabolism in children with ADHD is lower in the areas of the brain that control attention, social judgment, and movement. Low levels of dopamine (a brain chemical), which is a neurotransmitter (a type of brain chemical), are found in children with ADHD. Available evidence suggests that ADHD is genetic. However, the precise cause of the disorder is still unknown. What causes attention-deficit/hyperactivity disorder?ĪDHD is one of the most researched areas in child and adolescent mental health. Three major types of ADHD include the following:ĪDHD, combined type. This, the most common type of ADHD, is characterized by impulsive and hyperactive behaviors as well as inattention and distractibility.ĪDHD, impulsive/hyperactive type. This, the least common type of ADHD, is characterized by impulsive and hyperactive behaviors without inattention and distractibility.ĪDHD, inattentive and distractible type. This type of ADHD is characterized predominately by inattention and distractibility without hyperactivity. Inattention or attention-deficit may not be evident until a child faces the expectations of elementary school.
The symptoms of hyperactivity, when present, are almost always apparent by the age of 7 and may be present in very young preschoolers.
These symptoms usually occur together however, one may occur without the other(s). ADHD, also called attention-deficit disorder, is a behavior disorder, usually first diagnosed in childhood, that is characterized by inattention, impulsivity, and, in some cases, hyperactivity.
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