ASD was first included in the APA DSM-III in 1980 as “infantile autism” (APA, 2010). In today’s DSM-5, it is referred to as “Autism Spectrum Disorder” (APA, 2013). The most recent change from the DSM-IV to the DSM-5 was a significant diagnostic change because of reasons explained by the chair of the DMS-5 Task Force: “In suggesting these revisions, the work group has considered the many advances in the field of ASD and neurodevelopmental disorders, as well as concerns of advocacy groups, family members and the medical groups who treat those living with autism disorders” (APA, 2010).
The DSM-IV had ASD divided into four separate disorders: autistic disorder, Asperger’s disorder, childhood disintegrative disorder and pervasive developmental disorder not otherwise specified. Consistency in diagnosis was complicated, so the DSM-5 brought them together under the same umbrella to improve diagnostic accuracy (APA, 2013b). The reason for this was explained by a member of the DSM-5 Neurodevelopmental Disorders Work Group as, “The recommendation of a new category of autism spectrum disorders reflects recognition by the work group that the symptoms of these disorders represent a continuum from mild to severe, rather than being distinct disorders” (APA, 2010). All diagnoses from the DSM-IV are still applicable to the DSM-5 criteria for ASD, but instead of separately defined conditions, they are now on defined on a continuum. In addition to combining the diagnoses, the APA also added new components - overall development, course and language - all in an effort to create a more sensitive and accurate diagnostic standard (APA, 2010). A final change to the DSM-5 was to the diagnostic criteria: in DSM-IV the onset of ASD was not defined, but the DSM-5 indicates that ASD characteristics must be present from early childhood.