What is mental retardation?

The American Association on Mental Retardation gives the following definition: [2]

Mental retardation (MR) refers to substantial limitations in present functioning. It starts before age 18 and is characterized by significantly subaverage intellectual functioning, existing concurrently with related limitations in two or more of the following applicable adaptive skill areas:
  • communication
  • self-care
  • home living
  • social skills
  • community use
  • self-direction
  • health and safety
  • functional academics
  • leisure
  • work
Traditionally, MR has been classified into 5 categories:
  • mild MR – IQ from (50-55) to 70
  • moderate MR – IQ from (35-40) to (50-55)
  • severe MR – IQ from (20-25) to (35-40)
  • profound MR – IQ below (20-25)
  • MR, severity unspecified – this is diagnosed when there is a strong suspicion of MR, but the individual cannot be tested with standardized intelligence tests.