Significantly sub-average general intellectual functioning existing concurrently with deficits in adaptive behavior and manifested during the developmental period.
Low intelligence that renders a person to some extent ineffective in dealing with his or her affairs.
The absence of normal mental development, usually measured by the intelligence quotient and considered to be present in individuals scoring less than 70 on the Stanford-Binet scale. Many synonyms are used: mental deficiency, sub-normality, handicap and disability. Various types (intellectual, emotional) and degrees (borderline—68 to 85 on the Stanford-Binet, mild—57 to 67, moderate—36 to 51, severe—20 to 35, and profound under 20) are described. Mental retardation is one type of developmental disability and mental disorder.
A former term for learning disability, a condition that results in someone finding it difficult to learn skills or information at the same rate as others of a similar age.
Severe and profound mental retardation (SMR, PMR) are characterized by a below-average level of intellectual functioning that affects 3-4% of individuals diagnosed with mental retardation. According to the Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition, Text Revision (DSM-TV-TR), (DSM-IV) an IQ range of below 20-25 and 20-40 respectively generally typifies individuals with SMR and PMR (American Psychiatric Association [APA], 2000). Corresponding severe impairments in adaptive functioning are also apparent in these individuals. Both the APA and the American Association on Mental Retardation stress the importance of impaired adaptive functioning in the classification process. The AAMR classifies mental retardation according to the level of support that the individual requires. APA’s criteria for SMR is roughly equivalent to the AAMR’s individual who requires “extensive” levels of support, and for PMR the individual who requires “pervasive” levels of support.
Significantly lower-than-normal capacity for learning and cognitive development. As the name implies, the condition shows itself by clear delays in reaching developmental milestones. But where children of normal mental capacity can over-come initial developmental delay from other causes, mentally retarded children develop only to a certain plateau.
Disorder characterized by below-average intellectual capability with defects in the ability to learn and adapt. More males than females are affected. It may be genetic, congenital, biological, or psychosocial. On standardized intelligence tests with the average intelligence quotient (IQ) set at 90-110, mental retardation is generally classified as borderline with IQ 71-84; mild with IQ 50-70; moderate with IQ 35-49; severe with IQ 20-34; and profound with IQ below 20.
A disorder characterized by below-average intellectual function accompanied by deficits in behavior that occurs before age 18 years. The cause of retardation in most children is not known. However, some of the most common causes include genetic disorders such as Down syndrome and fragile X syndrome and environmental factors (such as maternal alcohol abuse during pregnancy). Other causes include brain damage from head injury or infection, such as bacterial meningitis.
Below average intelligence evident before the age of 18 associated with impaired learning or communication; poor social, community, or interpersonal adjustment; and inability to function independently (e.g., to support oneself, to live safety and healthfully).