Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS)

Three happy childrenWhat is Pervasive Developmental Disorder Not Otherwise Specified?

Pervasive Developmental Disorder Not Otherwise Specified (also known as PDD-NOS) is a developmental disorder characterized by impairments in reciprocal social interaction or the presence of stereotyped behavior, interests, and activities (American Psychiatric Association, 2000). A child with PDD-NOS does not fully meet the criteria for a specific Pervasive Developmental Disorder such as autism or Asperger’s Syndrome, but does demonstrate characteristics of the disorder.

Is PDD-NOS the same thing as PDD?

No. PDD-NOS is sometimes referred to incorrectly as PDD. A Pervasive Developmental Disorder (PDD) is not a diagnosis. It is a category of autism spectrum disorders identified in the DSM-IV. PDD includes: Autistic Disorder, Rett’s Disorder, Childhood Disintegrative Disorder, Asperger’s Syndrome, and PDD-NOS. PDD-NOS is a diagnosis.

How is PDD-NOS diagnosed?

Most practitioners rely on diagnostic criteria published in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition-Text Revision (DSM-IV-TR; American Psychiatric Association, 2000). The DSM-IV indicates that the category of PDD-NOS should be used when there is a severe and pervasive impairment in the development of social interaction (either verbal or nonverbal communication skills) or stereotyped behaviors/interests, but the criteria for other disorders are not met. There are at least three distinct subgroups represented in the category of PDD-NOS.

1. Individuals who display characteristics of Asperger’s Disorder, but present with mild cognitive or language delays.

2. Individuals with autistic-like tendencies, but with a later onset. Onset for autism occurs prior to the age of 3.

3. Individuals who display autistic-like tendencies, but with fewer stereotyped and repetitive behaviors.

PDD-NOS Treatment

Because guidelines for PDD-NOS are not as firm as other Developmental Disorders, there is often confusion regarding needed treatments and services. Some children with PDD-NOS can benefit from special education services provided by an IEP. However, not all students with PDD-NOS require specially designed instruction. Individuals with the same diagnosis may have very different strengths and weaknesses. It is important for school based teams to gather individualized information in order to determine the specific needs of the child. Regardless of the services needed, research overwhelmingly supports early interventions for students with PDD-NOS due to problems in the area of social interaction.


It is important to remember that within the school setting, multidisciplinary teams do not “diagnose” PDD-NOS, but rather determine eligibility for special education services based on the categories of eligibility established in IDEA (2004). PDD-NOS is not identified under IDEA, but most states allow its inclusion in either the category of Autism, Other Health Impaired, or Speech Language Impaired. Young children (usually under the age of 9) may also receive services under the umbrella of Developmental Delay.

Some symptoms associated with PDD-NOS can be difficult to distinguish from other developmental delays. Additionally, symptoms in young children identified with PDD-NOS can change over time. It is recommended that children diagnosed before the age of 3 be reevaluated one or two years after the initial diagnosis.

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