Special Olympics Africa > What is Intellectual Disability?

According to the World Health Organization (WHO) in the World Health Report 2001...

• Mental retardation is a condition of arrested or incomplete development of the mind characterized by impairment of skills and overall intelligence in areas such as cognition, language, and motor and social abilities.

• Also referred to as intellectual disability or handicap, intellectual disability can occur with or without any other physical or mental disorders.

• Although reduced level of intellectual functioning is the characteristic feature of this disorder, the diagnosis is made only if it is associated with a diminished ability to adapt to the daily demands of the normal social environment.

• Mental retardation is further categorized as mild (IQ levels 50-69), moderate (IQ levels 35-¬49), severe (IQ levels 20-¬34), and profound (IQ levels below 20).

According to the definition by the American Association on Mental Retardation (AAMR)...

• An individual is considered to have intellectual disability based on the following three criteria:

1. Intellectual functioning level (IQ) is below 70-75;
2. Significant limitations exist in two or more adaptive skill areas; and
3. The condition manifests itself before the age of 18.

• Adaptive skill areas are those daily living skills needed to live, work and play in the community and include: communication, self-care, home living, social skills, leisure, health and safety, self-direction, functional academics, community use and work.

• Adaptive skills are assessed in the person’s own environment across all aspects of his/her life. A person with limits in intellectual functioning who does not have limits in adaptive skill areas may not be diagnosed as having intellectual disability.

• Children with intellectual disability grow into adults with intellectual disability; they do not remain “eternal children.”

Prevalence of Intellectual Disability

• The prevalence figures vary considerably because of the varying criteria and methods used in the surveys, as well as differences in the age range of the samples. The overall prevalence of intellectual disability is believed to be between 1% and 3%, near 170 million individuals worldwide.
(World Health Organization, World Health Report 2001)

• Intellectual Disability is...

50 times more prevalent than deafness
25 times more prevalent than total blindness
10 times more prevalent that cerebral palsy
28 times more prevalent than neural tube defects such as spina bifada