The APA website now hosts a downloadable PDF describing SCD as follows:
SCD is characterized by a persistent difficulty with verbal and nonverbal communication that cannot be explained by low cognitive ability. Symptoms include difficulty in the acquisition and use of spoken and written language as well as problems with inappropriate responses in conversation. The disorder limits effective communication, social relationships, academic achievement, or occupational performance. Symptoms must be present in early childhood even if they are not recognized until later when speech, language, or communication demands exceed abilities.Further details are provided in an accompanying article in Psychiatric News:
The criteria describe “persistent difficulties in the social use of verbal and nonverbal communication” in four areas: using communication for social purposes such as greeting or exchanging information; changing communication to match context or the needs of the listener; following rules for conversation or storytelling, such as taking turns in conversation; and understanding what is not explicitly stated and nonliteral or ambiguous meanings of language.This sounds a lot like autism (at least at the "high functioning" end of the spectrum). In fact the main difference between SCD and ASD in DSM-5 is not some subtle distinction in the type of social communication impairment involved but the fact that an ASD diagnosis also requires evidence of repetitive and restricted behaviours:
while autism spectrum disorder (ASD) does encompass communication problems, it also includes restricted, repetitive patterns of behavior, interests or activities and gives equal weight to both communication issues and repetitive behaviors.As Will Mandy and colleagues have pointed out, many (if not most) kids accurately diagnosed with PDD-NOS conform to this profile. And it seems as though SCD is essentially a rebranding of PDD-NOS.
Because the symptoms described in SCD were not defined in previous editions of DSM, many individuals with such symptoms may have been lumped under the not otherwise specified category of pervasive development disorder.In Psychiatric News, Sue Swedo from the DSM-5 Neurodevelopmental Work Group says this:
“We believe social communication disorder will capture those children who have in the past been diagnosed with PDD-NOS as a way of drawing attention to the patient’s social communication impairments despite the absence of restrictive interests and repetitive behaviors.”This is confusing, because the line all along has been that PDD-NOS would be "folded into" ASD. From the same Psychiatric News article:
Possibly the most significant change is... the consolidation of DSM-IV criteria for autism, Asperger’s, childhood disintegrative disorder, and pervasive developmental disorder-not otherwise specific (PDD-NOS)—into one diagnostic category called autism spectrum disorder (ASD).It also contradicts the APA line that ASD prevalence won't be affected by DSM-5 changes. This is repeated in another new downloadable PDF from the APA website, describing Autism Spectrum Disorder.
The DSM-5 criteria were tested in real-life clinical settings as part of DSM-5 field trials, and analysis from that testing indicated that there will be no significant changes in the prevalence of the disorder.
More recently, the largest and most up-to-date study, published by Huerta, et al... found that DSM-5 criteria identified 91 percent of children with clinical DSM-IV PDD diagnoses, suggesting that most children with DSM-IV PDD diagnoses will retain their diagnosis of ASD using the new criteria. However, the same article hints at the fact that some people will be re-assigned:
Anyone diagnosed with one of the four pervasive developmental disorders (PDD) from DSM-IV should still meet the criteria for ASD in DSM-5 or another, more accurate DSM-5 diagnosis [italics added]. While DSM does not outline recommended treatment and services for mental disorders, determining an accurate diagnosis is a first step for a clinician in defining a treatment plan for a patient.The implication is that people who meet these criteria will be better off with an SCD diagnosis than they would have been with an ASD diagnosis. Put another way, people with similar social communication difficulties should receive different treatments depending on whether or not they also have restricted and repetitive behaviours.
Even if this made sense in theory and even if there was evidence to support it, the main problem from a practical viewpoint is that there are currently no services provided for people with an SCD diagnosis - because it doesn't yet exist. PDD-NOS may have been an inelegant and poorly defined diagnosis, but at least in some (not all) places, it actually meant something in terms of access to support. Those battles will all have to be refought. And even if SCD does eventually become recognised, it is classified in DSM-5 as a form of language disorder, completely separate from ASD, so service provision is likely to be at the same level as that for other language disorders (i.e., not good).
One of the main reasons cited for ditching the distinction between PDD-NOS, Asperger's and autism was a study by Cathy Lord and colleagues indicating that the use of these different diagnoses varies widely across different clinics in different states. As these authors admitted, this variability was likely to be driven at least by regional differences in service provision for the different diagnoses (I think I'm right in saying that the main outlier was California where PDD-NOS and Asperger's diagnoses were never given). DSM-5 was supposed to fix that problem but the worry is that it's going to make things a whole lot worse.
A Spanish translation of this article can be found at Autismo Diario.
MSN News article featuring quotes from Fred Volkmar, Temple Grandin, Cathy Lord, and Ari Ne'eman.