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OVERVIEW

DIAGNOSTIC CRITERIA

Autism spectrum disorder (ASD) is among the most common childhood disorders, with prevalence rates currently estimating 1 in 36 school-aged children (Maenner, Warren, Williams et al., 2023). ASD is four times more prevalent in males than females, but as will be highlighted later in this book, the diagnostic presentation of females assigned at birth is complex and, consequently, could suggest an underrepresentation of true female prevalence rates. Although the cause(s) of ASD is likely neurobiological/genetic in nature, the exact etiology remains unknown. As such, the diagnosis of ASD has historically been determined based on behavioral symptomatology that, through the lens of a medical model, are generally described as delays, deficits, impairments, or similar terminology that implies the need for remediation or a "cure" (Pellicano & den Houting, 2022). As the spectrum has broadened over the 21st century to include an increasing number of individuals with intact language and cognition, many autistic individuals identify as being neurodiverse or neurodivergent and do not seek to be cured or viewed as disordered, but rather wish to be accepted and supported for their unique differences (den Houting, 2019). Nevertheless, the label still implies that the individual is experiencing challenges, vulnerabilities, and in some cases delays/deficits that negatively affect multiple areas in life. The authors of this book have tremendous respect for neurodiversity, as we do for every individual across the extremely diverse and complex spectrum, including those more severely affected. Thus, in our aim to help educate and train clinicians on how to effectively identify ASD based on behavioral "symptoms," we strive to focus on the diagnostic label serving to enhance the quality of life and self-determination rather than to imply curing or fixing anybody. We will use terms such as symptoms, disorder, condition, and disability throughout the text given that this terminology is still part of the diagnostic criteria and medical nomenclature to which clinicians are exposed. We will also use identity-first language (autistic individual) opposed to person-first language (individual with autism) to respect that not all individuals view ASD as something separate from who they are.

The current diagnostic criteria for ASD put forth in the Diagnostic and Statistical Manual, Fifth Edition, Text Revision (DSM-5-TR; APA, 2022) require persistent symptoms in two broad areas: (1) the presence of delays/deficits/challenges in social communication and interaction in all three of the following areas either currently or by developmental history: (a) social-emotional reciprocity (e.g., shared interests, shared affect, and conversations), (b) nonverbal communication (e.g., integrated eye contact, and directed facial expressions, (c) use and understanding of gestures and body posture), and (d) in developing, maintaining, and understanding relationships (e.g., interactive imaginative play, interest in peers, and making friends); and (2) the presence of restricted, repetitive, or stereotyped behaviors that include at least two of the following four areas: (a) stereotypical motor movements or use of objects (e.g., hand flapping, spinning, lining up toys, and repetitive or stereotyped speech), (b) insistence on sameness or routine (e.g., difficulty with transitions, changes in routine, and rigidity in thinking), (c) highly restricted interests that become overly intense or all-consuming (e.g., intense interests on topics and fixation on objects), and (d) sensory processing impairments (e.g., hyper- or hypo-reactivity to sensory input, or seeking out sensory input). This combination of social vulnerabilities and stereotyped behaviors must be present in early development (even if symptoms go undetected until adolescence or adulthood) and clinically impairing across multiple contexts in life.

Rapid Reference 1.1

Social communication and interaction criteria (must include all three either currently or by history):

1. Challenges in social-emotional reciprocity
2. Challenges in nonverbal communication
3. Challenges in developing, maintaining, and understanding relationships

Restricted, repetitive, and stereotyped behaviors (must include at least two either currently or by history)

1. Stereotypical motor movements or use of objects
2. Insistence on sameness or routine
3. Highly restricted interests
4. Sensory processing impairments

In addition to listing the diagnostic criteria for the two categories of social communication/interaction symptoms and restricted, repetitive, and stereotyped behaviors, the DSM-5 has three severity levels that clinicians need to apply to both categories. Level 1 is specified for individuals who require support at the lowest level (e.g., symptoms interfere with functioning in one or more contexts, but they are mild); Level 2 is specified for those who require substantial support (e.g., there are marked impairments that interfere across multiple contexts); and Level 3 is specified for those who require very substantial support (e.g., delays or deficits are severe and entail comprehensive supports across contexts). Clinicians can specify different levels based on each category. For instance, an individual with intact language and cognition may only require Level 1 support for their social communication and interaction skills, but same individual's stereotypical behaviors might be so intrusive to life that Level 2 is required for this category.

DON'T FORGET

The DSM-5 has three levels of severity that need to be applied to each category of symptoms (social communication/interaction and restricted, repetitive, and stereotyped behaviors) as follows:

• Level 1: the individual requires support
• Level 2: the individual requires substantial support
• Level 3: the individual requires very substantial support

The DSM-5 also offers clinical specifiers for ASD that allow for descriptions of common co-occurring conditions. These include specifying whether ASD is accompanied by co-occurring intellectual impairment or language impairment (e.g., nonverbal, minimally verbal, phrase speech, and sentence speech), whether ASD is associated with a known genetic or other medical condition (e.g., Fragile X syndrome and Down syndrome), environmental factor, other neurodevelopmental (e.g., ADHD), mental (e.g., anxiety and depression), or behavioral problem, or whether co-occurring catatonia is present. Catatonic behaviors can include posturing, limited response to external stimuli, stupor, or mutism. Catatonia can be present in as many as 10% of autistic individuals, with features generally developing in late adolescence (Vaquerizo-Serrano, Salazar De Pablo, Singh, & Santosh, 2021).

DON'T FORGET

The DSM-5 has clinical specifiers that allow for indicating all co-occurring conditions. This helps inform levels of support needed as well as types of interventions.

• With or without accompanying intellectual impairment
• With or without accompanying language impairment
• Associated with a known genetic or medical condition, or environmental factor
• Associated with another neurodevelopmental, mental, or behavioral problem
• With catatonia

There is vast heterogeneity in symptom expression across the spectrum and throughout development, with some individuals experiencing only mild challenges in certain areas and other individuals experiencing quite debilitating challenges. Symptoms that impact autistic individuals are not just limited to the criteria for ASD, but also include varying levels of speech and language, cognition, emotional and behavioral regulation, and attention and executive functioning. Thus, clinicians need to be knowledgeable of these broader areas. When autism was first defined in the 1900s, the vast majority of individuals had co-occurring language and cognitive deficits that significantly affected development. However, current epidemiological data show that only about 38% of autistic children in the United States have co-occurring intellectual disability (ID; Maenner et al., 2023). This shift in levels of cognitive and language functioning has sparked a great deal of controversy in the field. Where historically there used to be a clear delineation of impairment to meet diagnostic criteria; currently, the diagnostic line between what is considered neurotypical and neurodiverse is quite blurred (Rodgaard, Jensen, Vergnes, Soulieres, & Mottron, 2019). This raises concerns about whether autism is a single condition or perhaps multiple disabilities, and whether the spectrum has become too broad to be accurately defined. Subtypes of autism were developed in the DSM-IV and DSM-IV-TR (APA, 1994, 2000) with autistic disorder, Asperger's disorder, pervasive developmental disorder, not otherwise specified, Rett's disorder, and childhood disintegrative disorder. However, research failed to show that these subtypes indeed had distinct phenotypes. Rather, research indicated that the main factor differentiating subtypes was the geographical site or clinicians providing the diagnoses (Lord, Petkova, Hus et al., 2012). Even expert...