Mental retardation

Mental retardation refers to significantly below-average intelligence. Mental retardation is categorized according to scores on tests that determine intelligence quotient (IQ) and other tests.

  • Mild mental retardation (IQ = 50 to 70): Mild mental retardation may not be obvious.
    • Children who are mildly mentally retarded usually learn to walk, talk, and do other activities of daily living, but at a slower pace than children who are not retarded.
    • They can learn to read, write, and do basic math.
    • As adults, they usually are able to live independently and provide for themselves with some assistance.
  • Moderate mental retardation (IQ = 35 to 55): Children who are moderately retarded develop much slower than children who are not retarded.
    • They usually do not progress beyond a second grade education level. However, they can learn routine tasks and talk in simple sentences.
    • As adults, they can function in well-supervised work situations and can live in group homes. They can live independently.
  • Severe mental retardation (IQ = 20 to 35): Children who are severely retarded have difficulty learning self-care activities, such as feeding themselves.
    • They develop few communication skills, but they can understand and respond to what other people say.
    • They usually can do things that a 2- to 3-year-old can do, such as feed themselves, use the bathroom, and dress themselves.
    • As adults, they may not be able to live alone.


Author: Jan Nissl, RN, BS
Sydney Youngerman-Cole, RN, BSN, RNC
Last Updated: October 12, 2006
Medical Review: Renée M. Crichlow, MD - Family Medicine
Adam Husney, MD - Family Medicine
Siobhan M. Dolan, MD, MPH - Reproductive Genetics
Renee H. Martin, PhD - Medical Genetics

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