Mental Retardation - Incidence & Characteristics
Some studies suggest that approximately 1% of the general population has
mental retardation (when both intelligence and adaptive behavior measures
are used). According to data reported to the U.S. Department of Education
by the states, in the 1998-99 school year, 610,445 students ages 6-21
were classified as having mental retardation and were provided special
education and related services by the public schools. This figure does
not include students reported as having multiple disabilities or those
in non-categorical special education pre-school programs who may also
have mental retardation.
Many authorities agree that people with mental retardation develop in
the same way as people without mental retardation, but at a slower rate.
Others suggest that persons with mental retardation have difficulties
in particular areas of basic thinking and learning such as attention,
perception, or memory. Depending on the extent of the impairment -- mild,
moderate, severe, or profound -- individuals with mental retardation will
develop differently in academic, social, and vocational skills.
For a table showing the typical support requirements
for different levels of mental retardation, click
Adapted from information
published by the National Information Center for Children and Youth with Disabilities