The brains of children and adults with attention deficit hyperactivity disorder (ADHD) seem to function somewhat differently from other people, and these differences in the ADHD brain typically produce the symptoms of the disorder. Research continues in this subject, and so new discoveries are being made frequently regarding how the brain works and how ADHD is produced by the brain. In general, however, it has been observed that individuals with ADHD typically have unusual amounts of certain chemicals and neurotransmitters in the brain. The ADHD brain also seems to function differently in a few key areas, all of which work together to produce the various aspects of ADHD.
People with ADHD typically have difficulty concentrating, demonstrate poor impulse control, and may be easily distracted from one task by other ideas or tasks. For years, research has focused on the role of dopamine and related brain chemistry as a contributor to the processes of the ADHD brain. Ritalin, one of the primary medications often used to treat ADHD, typically alters the way in which dopamine is produced and utilized within the brain. More recent research, however, has shown that a number of different areas of the brain seem to work together to produce the common symptoms of ADHD.
Four major areas of potential ADHD brain activity are the frontal lobe, the cerebral cortex, the limbic system, and the reticular activating system within the brain. The frontal lobe, for example, is where much of the research on neurotransmitters and neurological chemicals has been performed. This is where chemicals such as dopamine and glutamate are produced and used by the brain. In the ADHD brain, it seems that these chemicals are produced either in excess or in insufficient amounts to work properly. These changes in brain chemistry could produce affects such as an inability to concentrate or properly inhibit actions.
The cortex of the brain is also heavily involved with inhibiting activities of the brain. In the ADHD brain, the cortex does not seem to inhibit other areas of the brain properly, leading to those with ADHD often having inappropriate outbursts or speaking without first considering what is about to be said. This can lead to disruptive behavior in a classroom or business meeting and other negative consequences.
These outbursts can also be affected by the limbic system of the brain, which controls emotions. The ADHD brain does not seem to be properly controlled by the limbic system, and so individuals with ADHD may have wild mood swings or are unable to control emotional outbursts. As these different parts of the brain work together, the various symptoms of ADHD manifest not due to a single system, but through a combined effort of multiple parts of the brain.
The reticular activating system in the ADHD brain also seems to be different from a “normal” brain. This part of the brain seems to control some of the focus and concentration of the frontal lobe, as well as motor activity for a person. Unusual functions in this area may be responsible for some of the inability of a person with ADHD to concentrate on a given task, and for the tendency of those with ADHD to be hyperactive or find it difficult to sit still.