Intellectual Disability At IMFAR: Underdiagnosis of Autism Spectrum Disorders in Persons with Intellectual Disability

It comes as no surprise but very little is said  about Intellectual Disability at the IMFAR 2012 autism research convention oral presentations.  Prominent autism experts, including Catherine Lord, have noted in the past that intellectually disabled autistics are under represented in autism studies.  This is true even though the vast majority of persons with Autistic Disorder have intellectual disabilities.  The exclusion of the intellectually disabled from autism research reflects the challenges presented by working with low functioning, severely autistic, intellectually disabled subjects.  None of the oral presentations to date focused on the intellectually disabled autistics or discussed issues specific to them. Some studies mentioned that low cognitive subjects were not included but generalized their conclusions to all persons with autism. If you look hard enough though you can find mention of the intellectually disabled hidden in the IMFAR poster sessions.

One such poster involved a Gent University study by Herbert Roeyers and Martine Thys titled Underdiagnosis of Autism Spectrum Disorders in Individuals with Intellectual Disabilities.  The authors point out that only a limited number of studies have examined the prevalence of ASD in ID populations;  of intellectually disabled persons with autism spectrum disorders.  The authors felt it is important to study this co-occurrence relationship between ASD and ID in order to improve quality of life for persons with this co-morbidity relationship. In their study the authors arrived at a prevalence rate of 12.5% of persons with ASD in the ID population studied or approximately 10 times the percentage for persons with ASD in the general population.  Of the numbers identified with ASD only 38% were previously identified as having ASD indicating very serious underdiagnosis of ASD in the Intellectually Disabled population.

While the New York Times expresses great concern over possible future DSM5 exclusion of high functioning autistics, and prompts much reaction from autism experts, neither the NYT, nor most of the experts, even mention current underdiagnosis of autism in people with intellectual disability.