Attention deficit/hyperactivity disorder involves hyperactivity, impulsivity and problems with maintaining attention. Individuals with this disorder often have difficulty functioning in day-to-day life. ADHD becomes evident in childhood and often continues into adulthood. As MayoClinic.com points out, brain-imaging studies show that the brains of individuals with ADHD appear to function differently from those of people without the disorder.
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Four lobes make up the cortex of the brain. One of these areas, the frontal lobe, is at the front portion of the brain and is responsible for executive functioning. As the National Institute on Aging explains, executive functioning encompasses activities such as thinking, organizing, problem solving, memory, attention and movement. Problems associated with ADHD appear to involve this area of the brain.
Using functional magnetic resonance imaging, researchers including Mariya Cherkasova and Lily Hechtman, both of McGill University in Quebec, have found that the frontal lobes of individuals with ADHD have decreased activation.
In a study published in 2009, Cherkasova and Hechtman write that children with ADHD show less activity in their frontal lobes than children who do not have the disorder, whether they are resting or engaging in an activity. The authors add that the frontal lobes in these children function less during activities involving concentration, memory, decision-making and problem solving.
The prefrontal cortex, part of the frontal lobe, helps the brain sort through stimulation and decide what information is relevant and what to ignore. Writing in the “Annals of the New York Academy of Sciences,” Dr. Avis Brennan and Dr. Amy Arnsten of the the Yale University School of Medicine note that this brain region helps regulate movements, works to inhibit “inappropriate behavioral responses” and controls “impulses, language, attention, decision-making and error correction.”
Brain-imaging studies find that the prefrontal cortex of individuals with ADHD is smaller than that of individuals who do not have the disorder. Brennan and Arnsten believe this may help explain some of the problems associated with the disorder.
Another brain mechanism associated with the symptoms of ADHD, according to Cherkasova and Hechtman, is the frontostriatal circuitry in the frontal lobe. This brain mechanism contributes to the inhibition of certain behaviors. Cherkasova and Hechtman write that brain-imaging studies indicate a problem in the function of this circuitry in people with ADHD.
Brennan and Arnsten note that medications including methylphenidates, commonly prescribed to treat ADHD, work to improve the functioning of the prefrontal cortex. These medications affect certain brain chemicals, including dopamine and norepinephrine, and improve the level of activation of the prefrontal cortex. The result is often improved executive functioning.
Methlyphenidates do have the potential for certain side effects, however, including nervousness, sleep disturbance, nausea, loss of appetite, dry mouth and headache.
- “Annals of the New York Academy of Science”; Neuronal Mechanisms Underlying Attention Deficit Hyperactivity Disorder; Avis Brennan, M.D. and Amy Arnsten, M.D.; 2008
- “Canadian Journal of Psychiatry. Revue Canadienne De Psychiatrie”; Neuroimaging in Attention-Deficit Hyperactivity Disorder: Beyond the Frontostriatal Circuitry; Cherkasova and Lily Hechtman, M.D.; 2009
- MayoClinic.com: Attention-Deficit/Hyperactivity Disorder (ADHD) in Children
- Medline Plus: Methlyphenidate