I have posted several times about the high "co-morbidity" relationship between intellectual disability and autistic disorder (not autism spectrum disorder). The Canadian Psychological Association 2006 Canadian Senate Brief indicated that 80% of persons with autism (exclusive of Aspergers) have an intellectual disability. Two CDC surveys indicated that 44% and 41% of persons with an autism spectrum disorder have an intellectual disability. Since the autism spectrum includes Aspergers and persons who, by definition, do not have an intellectual disability the CPA and CDC figures appear to be fairly consistent. With such a high number of persons with classic autism or autistic disorder having an intellectual disability it is shocking that very little is mentioned about the relationship between intellectual disability and classic autism. The stigma associated with intellectual disability is so strong that the relationship is either ignored or outright disavowed.
For those who are ashamed of the large intellectually disabled segment of the classic autism population no information about intellectual disability and its role in autism will be allowed to breach the walls protecting their romanticized view of autism. For those who are more intellectually honest though I thought it would be helpful to post the DSM 5 definition of mental retardation which will now officially be called intellectual disability.