Definition of mental retardation

Mental retardation is a developmental condition that is characterized by significantly lower then average level of general intellectual functioning. It is failure to develop cognitive abilities and achieve an intelligence level that would be appropriate for their age group.


  • Mild Mental Retardation About 85% of persons that are Mental Retarded fall into this group.

IQ level 50-55 up to about 70

  • Moderate Mental Retardation About 10% of persons that are Mental Retarded fall into this group.


IQ level 35-40 to 50-55


  • Severe Mental Retardation About 3% to 4% of persons that are Mental Retarded fall into this group.


IQ level 20-25 to 35-40


Profound Mental Retardation About 1% to 2% of persons that are Mental Retarded fall into this group.


IQ level below 20 or 25


When there is a "STRONG" presumption of Mental Retardation but standard test can not be used to determine level of impairment it is called Mental Retardation Severity Unspecified.

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