The Developmental Disorders

All the major psychiatric illnesses are published in the Diagnostic and Statistical Manual for Mental Disorders (DSM) currently in its 5th edition and known as DSM V.  In the DSM, the category for developmental disorders is called ‘Neurodevelopmental disorders’, and the major diagnoses are intellectual disability and autism. In the previous edition of the DSM (DSM-IV) the disorders on the autism spectrum included Autism, Asperger’s and Pervasive Developmental Disorder Not Otherwise Specified (NOS).  In DSM V the different types of Autistic spectrum disorders are all included by using the term ‘Autism Spectrum Disorders’ (ASD). How are Autism Spectrum Disorders related to Intellectual Disability? When the autism spectrum disorders are grouped together with intellectual disability the umbrella term developmental disabilities may be used. The reason for this is that these disorders describe abnormal patterns of development. Despite this common ground, there are distinct differences between the two populations, with intellectual disability focusing on deficits in cognitive development and the autism spectrum disorders  focusing on deficits in emotional and social development. Both disorders are evident throughout the person’s life but the presentation changes as the person matures and gets older.   However, perhaps not surprisingly, as the development of mental function is affected so are other areas. For this reason people with intellectual disability are at increased risk of having an autism spectrum disorder, and the reverse is also true as people with autism spectrum disorders are at increased risk of intellectual disability.  Approximately 1 in 150 people have Autism and of those around 70% will also have an Intellectual Disability.