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Attention Deficit Hyperactivity Disorder
Printer-friendly versionWhat is Attention Deficit Hyperactivity Disorder?
Attention Deficit Hyperactivity Disorder (ADHD) is a neurobiological disorder. It is an illness or deficit of the nervous system most often caused by genetic or biological factors. ADHD is highly hereditary, occurring at a level of more than seven on a scale of one to ten, similar to height. ADHD is not new. It has been described in literature and medically documented for more than two centuries. ADHD is a chronic condition that can present at different levels of severity and rarely occurs by itself. There are three core symptoms: the inability to regulate attention; the inability to regulate activity; and difficulty with inhibitory behaviour resulting in impulsivity. Difficulty with regulating emotions is often an issue as well. It is important to note that symptoms of ADHD can vary from day to day, hour to hour and, while many children and adults may exhibit these symptoms, it is the degree of presentation, the inability to regulate them and the level of impairment that results in a diagnosis.
How Often Does ADHD Occur?
ADHD is the most common psychiatric disorder of childhood. Studies throughout the world report an incidence of ADHD in school age children of between 5% and 12%. This means, on average, there are at least one to three children in every class with ADHD. More boys than girls are diagnosed at a rate of three to one. However, since girls are less likely to display outward hyperactivity and since as many women as men are diagnosed in adulthood, we know many girls with ADHD are undiagnosed in childhood. Females are equally impaired in the areas of attention and social and academic problems as males. Eighty percent of adolescents with ADHD in childhood continue to meet the criteria for diagnosis in adolescence and more than sixty percent of adults with childhood ADHD report suffering from the symptoms of ADHD.
Are There Different Types of ADHD?
ADHD is classified into three categories based upon the clustering of the three core symptoms. Children and adults who have only hyperactive and impulsive symptoms are diagnosed as “ADHD, primarily hyperactive-impulsive subtype” (very rare and perhaps nonexistent); those who display only inattention are referred to as “ADHD, primarily inattentive subtype” (formerly known as ADD); and those who have both of these clusters are referred to as “ADHD, combined subtype” (the most common).
What causes ADHD?
Current research points to a decreased level of dopamine in certain parts of the brain as one of the causes of ADHD. Dopamine is a chemical manufactured by the brain which carries signals across the synapses of the brain. Norepinephrine, another chemical that also helps signals flow though the brain, may also be affected in people with ADHD. Magnetic Resonance Imaging (MRI), show certain parts of the brain are smaller in children with ADHD and that there is a decrease in blood flow, especially in the frontal lobes of the brain.