Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social communication and social interaction and the presence of restricted, repetitive behaviors.
Social communication deficits present in various ways and can include impairments in joint attention and social reciprocity as well as challenges using verbal and nonverbal communication behaviors for social interaction.
Restricted, repetitive behaviors, interests, or activities are manifested by stereotyped, repetitive speech, motor movement, or use of objects; inflexible adherence to routines; restricted interests; and hyper- and/or hypo-sensitivity to sensory input.
This definition is consistent with the diagnostic criteria for ASD described in the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5; American Psychiatric Association [APA], 2013).
The criteria specified in the DSM-5 reflect a number of changes from those in the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (Text Revision; DSM-IV-TR [APA, 2000]), the most notable of which are the following:
Elimination of the Pervasive Developmental Disorder (PDD) category that included diagnoses of Autistic Disorder, Asperger's Disorder, Childhood Disintegrative Disorder, Rett's Disorder, and Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS).
The DSM-5 criteria for ASD (the term used in place of PDD) encompass the social and behavioral deficits typically associated with these populations but no longer specify subtypes. (Note: The DSM-5 lists Rett syndrome, a genetic disorder, as a separate diagnosis in which disruptions of social interaction may be observed during the regressive phase).
Omission of criteria related to delay in or lack of development of spoken language and, instead, allowance for the clinician to specify whether ASD occurs "with or without accompanying language impairment."
Change in age of onset from "prior to 3 years" to the presence of symptoms "in the early developmental period."
Recognition of unusual reactions to sensory input (e.g., hyper- or hypo-reactivity to sensory input; unusual interest in sensory aspects of environment).
According to the DSM-5, individuals who meet the specified criteria are given the diagnosis of "autism spectrum disorder (ASD)" with one of three severity levels. Each severity level specifies the amount of support needed to function in the general community, given the individual's social communication skills and degree of restricted, repetitive behaviors. Severity may vary by context and may fluctuate over time. Severity ratings are used for descriptive purposes only and not to diagnose or determine eligibility for services (APA, 2013). See Paul (2013) for a more detailed discussion of DSM-5 changes and potential practice implications.
Although subtypes are no longer specified, the DSM-5 notes, "Individuals with a well-established DSM-IV TR diagnosis of autistic disorder, Asperger's disorder, or pervasive developmental disorder not otherwise specified should be given the diagnosis of autism spectrum disorder" (APA, 2013, p. 51).
Between 50% and 75% of individuals diagnosed with PDD under the DSM-IV-TR will maintain a diagnosis of ASD using DSM-5 criteria (see Smith et al.  for a review of relevant studies). The greatest decreases in diagnosis were among individuals with intelligence quotients (IQs) over 70 and those with a previous diagnosis of PDD-NOS or Asperger's Disorder (Maenner et al., 2014; Smith et al., 2015).
However, although ASD prevalence is likely to be lower under DSM-5 than under DSM-IV-TR, this trend may be offset by (a) increased awareness of ASD and the DSM-5 criteria; (b) more detailed description and documentation of behaviors that meet the new ASD criteria; and (c) adaptation of policies and tools for determining eligibility in response to DSM-5 changes (Maenner et al., 2014).
Some children who do not meet the criteria for ASD under DSM-5 may meet the criteria for social communication disorder. According to the DSM-5, "Individuals who have marked deficits in social communication, but whose symptoms do not otherwise meet criteria for autism spectrum disorder, should be evaluated for social (pragmatic) communication disorder" (APA, 2013, p. 51).
It is important to
differentiate between ASD and
social communication disorder (Rosin, 2016). Speech-language pathologists (SLPs) are instrumental in making this differential diagnosis and ensuring that individuals with ASD and those with social communication disorder gain access to services. See ASHA's Practice Portal page on
Social Communication Disorder.
Regardless of the presence or absence of difficulties acquiring the form and content of language, all individuals with ASD are eligible for speech-language services due to the pervasive nature of the social communication impairment. Therefore, SLPs need to advocate for inclusion of language intervention for individuals diagnosed with ASD and ensure that individuals with ASD also receive a diagnosis of language disorder (LD), when they meet the criteria. See ASHA's Practice Portal pages on
Spoken Language Disorder and
Written Language Disorder.
At its core, communication is a social process. The social communication issues experienced by individuals with ASD also affect their communication partners. Family members, friends, teachers, and coworkers face the challenge of learning to recognize and respond to subtle bids for communication and to interpret the communication functions of challenging behaviors.
Individuals with ASD report a desire to have friendships and relationships, despite their social communication challenges. However, peers often feel ineffective in social exchanges with an individual with ASD and may avoid that person or react to social overtures in a negative way (e.g., by teasing or bullying). This lack of appropriate engagement and bullying can have a negative impact on the development of social skills.