The category of pervasive developmental disorder (PDD-NOS) in DSM-IV included the previous separate disorders for which the following names were given: infantile autism, childhood autism, Kanner’s autism, high-functioning autism, atypical autism, pervasive developmental disorder NOS, Childhood Disintegrative Disorder and Asperger’s disorder (American Psychiatric Association 2000; Gibbs et al. 2012). The notion that these were discrete disorders began to unravel as the distinctions between PDD-NOS and for example, Asperger’s eroded. Reflecting the porosity of boundaries and with the literature now replete with ASD studies, DSM-5 followed suit.

DSM-5 has two main criteria sets: Diagnostic “A” criterion contains both deficits in social communication and social interaction. The disturbance in social relatedness includes marked impairment in non-verbal communication, peer relationships and social-emotional reciprocity. Impairments in communication include either a delay or total lack of spoken language (without an attempt to compensate through other means) or, for verbal individuals, a marked difficulty in the ability to sustain or initiate conversation, stereotyped and repetitive (or idiosyncratic) language and lack of developmentally-appropriate make-believe or social play. There are three items with descriptors around the items. The first of these: social-emotional reciprocity is conceived as a range from failure of the reciprocal behavior at one end of the range to a reduced quantity and quality of reciprocal behavior at the other end. The second item, nonverbal communicative behavior spans poor eye contact to the absence of nonverbal communication. Third is the area of social relationships. Here the range includes awkwardness of interaction to absence of peer interest. All three are required to fulfill “A” criterion. To capture the range of dysfunction for criterion “A” the severity scale from “1” denoting support required to and “3” substantial support such as the presence of an specialized caretaker should be applied.

Criterion B has four items that describe the behaviors of ASD. The first is repetitive motor stereotypies, repetitive use of objects, or repetitive speech. Echolalia, stereotypies and lining up toys are examples. The second focuses on routines and rituals. The behaviors could be verbal such as greeting rituals, or thinking patters such as expecting furniture to remain exactly in place or simply changing from one behavior to another as is required in transitioning from one play activity to another. The third is overvalued interest in an object, sensation or activity with a significant disinterest in other possible stimuli. Collecting every version of the same song for example shows the narrowness of the person’s interest. Lastly is sensory abnormalities that can vary from hyper to hypo-reactive. The variety of behaviors associated with sensory experiences with, for example, water play that might be due to the fascination with the temperature or the way light plays on it or the characteristics of liquids demonstrates the innumerable variations to be considered for this item. Compared to “A” criterion that requires every item to be satisfied, only two of these four items must be met for a total of six items. As with Criterion “A” a severity level should be applied that specifies whether low (level one) to high (level three) support is appropriate.

Criterion C changes the expected onset to be identified to the early developmental period as noted above. Criterion D like all disorders must be accompanied by clinically significant functional impairment. And finally, criterion E is the exclusion criterion that eliminate ASD if another disorder better describes the findings. The most common example of this would be global developmental delay which would include motor and/or sensory delays as part of the total presentation.

In addition to the specification of severity, other specifies are now part of the DSM-5 diagnostic package (McPartland et al. 2012). Instead of indicating cognitive impairment on Axis 2, the ASD diagnosis will include the presence or absence of accompanying intellectual impairment. DSM-5 has done away with the multiaxial system. The place for this common comorbid problem finds its way as a modifier of ASD. Although social communication can be severely delayed in ASD, a separate diagnostic item is no longer part of the criteria. Item 2 under criterion A is about nonverbal communication and echolalia which was part of verbal deviances in previous DSM editions and is no longer a main item and is found under repetitive movement’s item 1 criterion “B”. Hence it is important to specify whether ASD exists with or without a language impairment.