Mental retardation or intellectual disability, (MR/ID), exists in children whose brains do not develop properly or function within the normal range. There are four levels of retardation: mild, moderate, severe, & profound. Sometimes, MR/ID may be classified as other or unspecified. Mental retardation involves both a low IQ & problems adjusting to everyday life.
MR/ID can result in learning, speech, physical, & social disabilities. Severe cases are diagnosed at birth. However, milder forms might not be noticed until a child fails to meet a common developmental goal. Almost all cases of MR/ID are diagnosed by the time a child reaches 18 years of age.