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Intellectual disability (ID), also called intellectual development disorder (IDD) or general learning disability, and formerly known as mental retardation (MR), is a generalized neurodevelopmental disorder characterized by significantly impaired intellectual and adaptive functioning. It is defined by an IQ score below 70 in addition to deficits in two or more adaptive behaviors that affect everyday, general living. Once focused almost entirely on cognition, the definition now includes both a component relating to mental functioning and one relating to individuals' functional skills in their environments. As a result of this focus on the person's abilities in practice, a person with an unusually low IQ may not be considered intellectually disabled. Intellectual disability is subdivided into syndromic intellectual disability, in which intellectual deficits associated with other medical and behavioral signs and symptoms are present, and non-syndromic intellectual disability, in which intellectual deficits appear without other abnormalities. Down syndrome and fragile X syndrome are examples of syndromic intellectual disabilities. Intellectual disability affects about 2–3% of the general population. 75–90% of the affected people have mild intellectual disability. Non-syndromic or idiopathic cases accounts for 30–50% of cases. About a quarter of cases are caused by a genetic disorder. Cases of unknown cause affect about 95 million people as of 2013. The terms used for this condition are subject to a process called the euphemism treadmill. This means that whatever term is chosen for this condition, it eventually becomes perceived as an insult. The terms ''mental retardation'' and ''mentally retarded'' were invented in the middle of the 20th century to replace the previous set of terms, which were deemed to have become offensive. By the end of the 20th century, these terms themselves have come to be widely seen as disparaging, politically incorrect, and in need of replacement. The term ''intellectual disability'' is now preferred by most advocates and researchers in most English-speaking countries. , the term "mental retardation" is still used by the World Health Organization in the ICD-10 codes, which have a section titled "Mental Retardation" (codes F70–F79). In the next revision, the ICD-11 is expected to replace the term ''mental retardation'' with either ''intellectual disability'' or ''intellectual developmental disorder'', which the DSM-5 already uses. Because of its specificity and lack of confusion with other conditions, the term "mental retardation" is still sometimes used in professional medical settings around the world, such as formal scientific research and health insurance paperwork. ==Signs and symptoms== The signs and symptoms of intellectual disability are all behavioral. Most people with intellectual disability do not look like they are afflicted with such, especially if the disability is caused by environmental factors such as malnutrition or lead poisoning. The so-called typical appearance ascribed to people with intellectual disability is only present in a minority of cases, all of which are syndromic. Children with intellectual disability may learn to sit up, to crawl, or to walk later than other children, or they may learn to talk later.〔 Both adults and children with intellectual disability may also exhibit some or all of the following characteristics:〔 * Delays in oral language development * Deficits in memory skills * Difficulty learning social rules * Difficulty with problem solving skills * Delays in the development of adaptive behaviors such as self-help or self-care skills * Lack of social inhibitors Children with intellectual disability learn more slowly than a typical child. Children may take longer to learn language, develop social skills, and take care of their personal needs, such as dressing or eating. Learning will take them longer, require more repetition, and skills may need to be adapted to their learning levels. Nevertheless, virtually every child is able to learn, develop and become a participating member of the community. In early childhood, mild intellectual disability (IQ 50–69) may not be obvious, and may not be identified until children begin school.〔 Even when poor academic performance is recognized, it may take expert assessment to distinguish mild intellectual disability from learning disability or emotional/behavioral disorders. People with mild intellectual disability are capable of learning reading and mathematics skills to approximately the level of a typical child aged nine to twelve.〔 They can learn self-care and practical skills, such as cooking or using the local mass transit system.〔 As individuals with intellectual disability reach adulthood, many learn to live independently and maintain gainful employment. Moderate intellectual disability (IQ 35–49) is nearly always apparent within the first years of life. Speech delays are particularly common signs of moderate ID.〔 People with moderate intellectual disability need considerable supports in school, at home, and in the community in order to participate fully. While their academic potential is limited, they can learn simple health and safety skills and to participate in simple activities.〔 As adults, they may live with their parents, in a supportive group home, or even semi-independently with significant supportive services to help them, for example, manage their finances. As adults, they may work in a sheltered workshop.〔 People with severe or profound intellectual disability need more intensive support and supervision their entire lives.〔 They may learn some activities of daily living. Some require full-time care by an attendant.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Intellectual disability」の詳細全文を読む スポンサード リンク
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