A Stage Set for Confusion
PDD is an acronym for pervasive developmental disorder. As a classification of conditions, PDD made its first appearance in the Diagnostic and Statistical Manual of Mental Disorders (DSM-III) in 1980. PDD encompassed infantile autism, childhood onset pervasive developmental disorder, and a residual category known as Atypical PDD. The Atypical PDD diagnosis has led to a plethora of confusion between autism and PDDs.
In 1994, PDD-NOS, or Pervasive Developmental Disorder, Not Otherwise Specified replaced Atypical PDD in the DSM-IV. In short, both PDD-NOS and Atypical PDD described conditions where a child met certain criteria for an autism spectrum diagnosis, but not enough for an identifiable disorder such as Asperger’s or classic autism. This has led to much confusion for parents and caregivers new to an autism spectrum diagnosis, especially since many labels and descriptions of PDDs such as Atypical PDD are still used in some literature.
So What is the Difference Between Autism and PDD?
In simplest terms, the easiest way to understand what is the difference between autism and PDD is by understanding umbrella terms. Pervasive development disorder is an umbrella term or categorical classification. PDDs, at least in terms of diagnostic criteria, are a group or spectrum of disorders and conditions characterized by similar symptoms. Those symptoms include impairment in social interactions, delays in verbal communication or language skills, stereotypical behaviors, and impaired nonverbal communication skills. The severity of symptoms, types of stereotypical behaviors and other factors differentiate the disorders classified under pervasive developmental disorders.
In short, autism, whether infantile, high functioning or classic is a disorder classified under PDDs in the DSM-IV. Therefore, it is reasonable to say that autism is a type of PDD, under current diagnostic criteria. Specifically, it is classified as Autistic Disorder. Patients must present with six or more symptoms or behaviors from a list of common impairments and developmental disabilities. These include impairments in social skills such as maintaining eye contact, nonverbal communications (body language,) poor peer relationships, lack of two-way displays of emotional or social responses, restrictive preoccupations with patterns of interest or behaviors, and verbal communication impairments.
Proposed Changes to the DSM-V
The American Psychiatric Association (APA), publishers of the DSM, have proposed changes to the way autism spectrum disorders and PDDs are classified in the DSM-V, scheduled for publication in May, 2013. Under the proposed changes, autism spectrum disorders would receive their own classification in the new DSM. The APA proposes to remove rare disorders such as Retts and move autism spectrum disorders such as Autistic Disorder and Asperger’s to their own category.
The APA proposes to subsume current disorders such as PDD-NOS into other disorders to further reflect the belief that autism is a spectrum of disabilities ranging in severity from mild to severe. Therefore, rather than having a distinct PDD, children would be diagnosed according to the severity of their impairments on the autism spectrum. Such actions would help prevent future confusion between autism and PDD. The new category and diagnostic criteria would identify children with autism spectrum disorders (ASDs) rather than PDDs.
References and Resources
Centers for Disease Control: https://www.cdc.gov/ncbddd/autism/hcp-dsm.html
National Institute of Neurological Disorders and Stroke: https://www.ninds.nih.gov/disorders/pdd/pdd.htm
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