Mental Retardation

Mental retardation (MR) is a developmental disability, defined by looking at three aspects of a child. IQ score, adaptive functioning, and the age of onset determine where a child lies in the continuum of mental retardation.

A numerical component of MR is defined by an IQ intelligence test. An IQ test measures and predicts how well individuals learn in their environment. The average IQ score of a typical developing child falls between 80 and 119. An IQ score below 70 to 75 characterizes a child for further evaluations to determine if the child is mentally retarded. IQ levels below 75 are categorized into several levels. These levels represent the amount of support individuals with MR require. The four levels of support include: intermittent (IQ score 55-65), limited (IQ score 35-55), extensive (IQ score 25-35), and pervasive (IQ score 20-25).

Adaptive functioning, the way an individual functions in society, is another aspect required for a valid definition of MR. Included in adaptive functioning are intellectual, emotional, physical, and environmental considerations. Daily living skills such as dressing, personal hygiene, eating, and receptive and expressive communication, as well as safety awareness and other basic skills, are evaluated for adaptive functioning. A child must show poor development in at least two of the adaptive functioning categories to be considered mentally retarded.

The last aspect for a definition of MR is the age of onset of the preceding characteristics. Under the definition of MR from the American Association on Mental Retardation, the age of onset has to be in childhood before the age of eighteen. As discussed in the following section, MR can develop even before the baby is born.

Individuals who fall below the IQ standard, show poor adaptive functioning in two or more areas, and had the onset of these conditions occur in childhood are considered to be mentally retarded. This does not mean that the individual will not learn and develop but, instead, that intervention will be necessary to assist the individual with his or her development.