The terminology of autism has changed a great deal over the past 100 years as researchers gained knowledge about the condition. The current diagnostic criteria, in place since the fifth edition of the Diagnosis and Statistical Manual of Mental Disorders (DSM-5) was published in 2013, reclassifies all previously distinct autism-related diagnoses under one umbrella, that of autism spectrum disorder (ASD). The word spectrum describes the wide variety of behaviors and other symptoms at differing severity levels in people with autism. ASD describes symptoms in two areas:
The criteria also provide a basis for rating the severity of symptoms in both areas as 1 (requiring support), 2 (requiring substantial support), or 3 (requiring very substantial support).
Social (pragmatic) communication disorder (SCD) is a newer, separate diagnosis added in the DSM-5. SCD describes difficulties in social interaction, verbal and nonverbal communication, understanding of social situations, and pragmatics (language as used within different contexts). ASD must be ruled out before SCD can be diagnosed – no one would be diagnosed with both. Some people originally diagnosed in previous years with autism or another related condition might be diagnosed with SCD if tested again under the new criteria.
Autism spectrum disorder includes several conditions that were considered distinct diagnoses until 2013. The following classifications are no longer used: