Quick, according to the DSM-IV section on pervasive developmental disorders (PDDs), what are the differences between autism (offically "autistic disorder"), high-functioning autism, Asperger syndrome, and PDD not otherwise specified (PDD-NOS)? If you can tell me without looking it up that autism requires 6 total symptoms from 3 categories, Asperger syndrome requires 3 symptoms from 2 categories, PDD-NOS requires only 1 symptom, and there's no such thing as "high-functioning autism" in DSM-IV, then you're much more knowledgeable than I am.
Hopefully, it is easy to see why the workgroup tasked with revising the autism diagnosis in DSM-5 tried to simplify this complex chimera into something more comprehensible. Most experts post-DSM-IV have concluded that all of these conditions overlap quite a bit and are best conceptualized as different presentations along a continuum (clinically-speaking, of course; research into etiology is a whole different ball of wax). Hence the term autism spectrum disorder (ASD). Academia has favored using ASD instead of PDD for a while now, and this seems to have filtered into the popular culture over the past decade, as you can see in Google Trends. So what does the DSM-5 change when it comes to the diagnostic criteria for autism?
The 3 categories of autism symptoms in DSM-IV encompass impairments in social interaction, communication, and repetitive or stereotyped patterns of behavior. DSM-5 eliminates the communication category, partly by combining social communication deficits (such as difficulty initiating or sustaining a conversation) with the other social impairments (such as inability to make eye contact or share enjoyment) into one category. Thus, the 2 categories in DSM-5 are "social communication & interaction" and "restricted, repetitive behavior," and impairment in both have to be present to diagnose someone with ASD. The restricted behaviors can now include hypo- or hypersensitivity to sensory stimuli, which is seen in many who are on the spectrum. Language delay, which formerly distinguished autism from Asperger syndrome, is no longer part of the criteria for diagnosing ASD, since that is now felt to mainly reflect differences in IQ.
The impairments can also be "by history," which means that a child who previously had inability to make eye contact but improved after behavioral therapy can still have that count towards the diagnosis. The age criterion has been changed from "onset prior to 3 years" to onset during the "early developmental period." As with many other parts of DSM-5, there is now a dimensional aspect, with 3 different levels of ASD severity based on the extent of impairment in each individual. Also, different specifiers can be added to the diagnosis, e.g. ASD with intellectual disability, or speech delay, or regression in functioning, or specific genetic conditions.
No change is without controversy, and there are some big ones here. Not surprisingly, the elimination of Asperger syndrome as a separate entity sparked an outcry amongst some in the Aspie community. Another controversial aspect is that ASD, unlike other entities such as ADHD, now actually has tighter diagnostic criteria than some of the previous PDDs such as Asperger's and PDD-NOS, resulting in fear that some who already have those labels will lose their diagnosis after the DSM-5 comes out. In this month's Journal of the American Academy of Child and Adolescent Psychiatry, members of the DSM-5 Neurodevelopmental Disorders Workgroup sought to reassure the public (subscription required):
With respect to the PDDs, the DSM-5 has essentially moved from letter grades to a “pass-or-fail” system. Everyone with an existing autistic disorder, Asperger disorder, or PDD-NOS diagnosis (e.g., “A,” “B,” “C”) should simply be reassigned (e.g., “pass”), and not formally rediagnosed unless there is some clinical reason to do so.It will be interesting to see whether this guidance is followed out in the real world. While the DSM-5 taketh away, it also giveth, in the form of a new category called social communication disorder (SCD). This diagnosis is for someone who has difficulties with "using verbal and nonverbal communication for social purposes" but no restricted, repetitive behaviors. Some of the people who previously would have been diagnosed with PDD-NOS would likely fall under this category. It will also be all too easy to conclude that the DSM-5 is pathologizing social awkwardness and turning it into a disorder, just as many felt that DSM-IV turned shyness into a disorder called social phobia. The truth, unfortunately, will take time to emerge and will likely be complicated, as in the case of shyness vs. social phobia.
For me as a practicing clinician, the new ASD diagnosis is one of the best changes in DSM-5. Soon, I may not even have to reach for a reference book to see if someone meets criteria for an autism spectrum disorder.
