- published: 30 Nov 2010
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Attention deficit hyperactivity disorder (ADHD, similar to hyperkinetic disorder in the ICD-10) is a neurodevelopmental psychiatric disorder in which there are significant problems with executive functions (e.g., attentional control and inhibitory control) that cause attention deficits, hyperactivity, or impulsiveness which is not appropriate for a person's age. These symptoms must begin by age six to twelve and persist for more than six months for a diagnosis to be made. In school-aged individuals inattention symptoms often result in poor school performance. Although it causes impairment, particularly in modern society, many children have a good attention span for tasks they find interesting.
Despite being the most commonly studied and diagnosed psychiatric disorder in children and adolescents, the cause in the majority of cases is unknown. The World Health Organization estimates that it affected about 39 million people as of 2013. It affects about 6–7% of children when diagnosed via the DSM-IV criteria and 1–2% when diagnosed via the ICD-10 criteria. Rates are similar between countries and depend mostly on how it is diagnosed. ADHD is diagnosed approximately three times more in boys than in girls. About 30–50% of people diagnosed in childhood continue to have symptoms into adulthood and between 2–5% of adults have the condition. The condition can be difficult to tell apart from other disorders as well as from high levels of activity that are still within the normal-range.
A fact is something that has really occurred or is actually the case. The usual test for a statement of fact is verifiability—that is, whether it can be demonstrated to correspond to experience. Standard reference works are often used to check facts. Scientific facts are verified by repeatable careful observation or measurement (by experiments or other means).
The word fact derives from the Latin factum, and was first used in English with the same meaning: a thing done or performed, a meaning now obsolete. The common usage of "something that has really occurred or is the case" dates from the middle of the sixteenth century.
Fact is sometimes used synonymously with truth, as distinct from opinions, falsehoods, or matters of taste. This use is found in such phrases as, "It is a fact that the cup is blue" or "Matter of fact", and "... not history, nor fact, but imagination." Filmmaker Werner Herzog distinguishes clearly between the two, claiming that "Fact creates norms, and truth illumination."