People with intellectual disabilities are those who develop at a below average rate and experience difficulty in learning and social adjustment. Intellectual disabilities are not diseases, nor should they be confused with mental illness.

Intellectual disabilities means significantly subaverage general intellectual functioning existing concurrently with deficits in adaptive behavior and manifested during the developmental period, that adversely affects a child's educational performance.
    
'General intellectual functioning' is typically measured by an intelligence test. Persons with intellectual disabilities usually score 70 or below on such tests.

Intellectual disabilities are not diseases, nor should they be confused with mental illness. Children with intellectual disabilities become adults -- they do not remain "eternal children." They do learn, but slowly, and with difficulty.

Some studies suggest that approximately one percent of the general population has intellectual disabilities (when both intelligence and adaptive behavior measures are used).

Many authorities agree that people with intellectual disabilities develop in the same way as people without intellectual disabilities, but at a slower rate. Others suggest that persons with intellectual disabilities 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 intellectual disabilities will develop differently in academic, social and vocational skills.

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