Chapter III - References
Most experts agree that it is important to identify children with developmental delays or disorders as early as possible. Intervention at earlier stages in the child's development may have a greater chance of reducing the short-term and long-term negative consequences of these disorders (Guralnick, 1998).
There is no single way that autism is first identified in young children; this will vary somewhat depending on the individual child. In addition, the sequence in which components of the assessment process are done may vary. Therefore, the order of the recommendations in this chapter of the guideline is not necessarily the order in which these actions will occur for a particular child. For example, the concern of possible autism may be the result of a developmental assessment, and therefore, may identify the need for more in-depth screening. In this situation, the developmental assessment would occur prior to the screening. Regardless of the order in which they appear, all elements of the assessment process discussed in this chapter are important for professionals and parents to consider when assessing young children with possible autism.
In some instances, information gathered in the assessment of autism may be used as a part of the process to determine if a child is eligible for various programs or services. The recommendations in this guideline, however, are intended only to consider issues related to clinical practice and, therefore, do not address issues specific to program eligibility.
Diagnostic criteria for autism in DSM-IV
The diagnostic labels and diagnostic criteria for autism and similar disorders have changed several times since autism was first defined almost 50 years ago. The diagnostic criteria for autism that are currently most widely accepted within the US are those specified in the American Psychiatric Association, Diagnostic and Statistical Manual for Mental Disorders, Fourth Edition, which is commonly referred to as "DSM-IV."
The DSM-IV divides the general category of pervasive development disorders into several subcategories including: (1) autistic disorder, (2) pervasive developmental disorder not otherwise specified (PDD-NOS), (3) Asperger's disorder, (4) Rett's disorder, and (5) childhood disintegrative disorder.
Defining "autism" to include autistic disorder and PDD-NOS
As noted in Chapter I, in this guideline the term autism is used to include both autistic disorder and PDD-NOS as defined in the DSM-IV. The panel considered this appropriate because autistic disorder and PDD-NOS are not qualitatively different conditions, but are merely parts of a continuum of the more general category of pervasive developmental disorders. In addition, since the clinical picture can change over time for a child with autism, a particular child may at times meet the criteria for PDD-NOS and at other times meet the criteria for autistic disorder. Therefore, the panel considered it both appropriate and simpler to define autism in this guideline to include both autistic disorder and PDD-NOS. DSM-IV diagnostic criteria are shown in Table III-1 for autistic disorder and in Table III-2 for PDD-NOS.Diagnoses not covered in this guideline
This guideline does not deal with Asperger's disorder, Rett's disorder, or childhood disintegrative disorder, since these three conditions are usually not diagnosed until a child is over 3 years old. For this reason, discussions of assessment and intervention methods for these three conditions were considered to be outside the scope of the guideline.
Use of changing diagnostic criteria in studies reviewed
Some of the studies discussed in later sections of the guideline use older or different diagnostic criteria for autism. Many studies use earlier versions of the DSM, specifically the DSM-III (released in 1980) or the DSM-III-R (released in 1987). The DSM-IV was issued in 1994. Another criterion cited in some studies is the International Classification of Disease, 10th Edition (ICD-10) which is very similar to the DSM-IV. Still other studies use diagnostic criteria for autism proposed by Rutter in 1978. In addition, some of the studies reviewed evaluated children with autistic disorders and children with PDD-NOS in separate groups, while other studies combined these children into the same group.
To avoid confusion, descriptions of specific scientific studies presented in this guideline all specify the diagnostic criteria for autism used in that study and describe the study using the same diagnostic terms as used by the authors of that study.
A diagnosis of autistic disorder is made when the following criteria from A, B, and C are all met.
A diagnosis of pervasive developmental disorder, not otherwise specified (PDD-NOS) is made when there is a severe and pervasive impairment in the development of reciprocal social interaction or verbal and nonverbal communication skills, or when stereotyped behavior, interests, and activities are present, but the criteria are not met for a specific pervasive developmental disorder, schizophrenia, schizotypal personality disorder, or avoidant personality disorder. For example, this category includes "atypical autism" presentations that do not meet the criteria for autistic disorder because of late age at onset, atypical symptomatology, or subthreshold symptomatology, or all of these.
Reprinted with permission from the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. Copyright 1994 American Psychiatric Association.
<Alternative diagnostic terminology
The DSM-IV criteria were determined through an extensive process of consensus building and field testing, and they represent the most widely accepted and utilized diagnostic model across the country. Recently, an alternative diagnostic model has been proposed by Zero to Three: National Center for Infants, Toddlers, and Families. However, to date, that model lacks a formal research base and may define a different population of children. The Zero to Three diagnostic model has not yet gained broad acceptance among developmental specialists, and is offered by its authors as a "first step" and "evolving framework." Thus, while provocative, it is not felt to be appropriate as a basis for the diagnosis of autism at this time.
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Revised: November 1999