Insight into PDD-NOS Symptoms

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What is PDD NOS?

Pervasive developmental disorder, not otherwise specified (PDD-NOS) is a neurological disorder that falls, with classic autism and Asperger syndrome (AS), under the umbrella term of autistic spectrum disorders (ASD). According to the Centers for Disease Control and Prevention, an individual diagnosed with an ASD, has qualitative impairments in three main areas:

  • Language and communication
  • Social interaction
  • Restrictive and repetitive interest, activities and behaviors

When an individual is diagnosed with PDD-NOS, symptoms from these three areas are present but specific sub-criteria for AS or classic autism have not been met.

PDD-NOS Symptoms

There is no specific set of traits that delineates PDD-NOS. Symptoms can vary widely and are usually considered by a multi-disciplinary team before a diagnosis is given. Characteristics present in childhood may change, and may increase or decrease in severity as a child develops and experiences new situations. Since the symptoms of PDD are the same as those in classic autism and Asperger syndrome, the difference in diagnosis usually comes from the number or pattern of characteristics displayed.

Individuals with PDD-NOS may have difficulty communicating effectively. Some may not be able to talk or understand speech. Others may use an advanced vocabulary but have trouble processing a teacher’s oral instructions. Some may have a very literal understanding of language and have difficulty starting or maintaining conversations. It is common for students with PDD-NOS to speak with unusual tone of voice, rhythm or pitch and to have trouble understanding body language and facial expressions.

People with PDD-NOS are often unable to make friends or keep friendships going. They may approach peers but not know how to join in on a conversation or they may seem uninterested in other people. They may not be able to understand or communicate feelings and they may be ostracized because of inappropriate reactions to situations (e.g. laughing when someone is upset) or odd behaviors.

Some people with PDD-NOS may have symptoms that include repetitive movements like hand-flapping or spinning. Children may play with toys in an unusual way such as lining cars up. Some may have interests or activities that seem obsessive and a strong need for familiar routines. Others may have difficulty transitioning from one activity to another.

Other PDD-NOS Symptoms

Understanding PDD-NOS can be challenging because no child or adult will present with the same symptoms. To further complicate matters, some people will display characteristics from outside of the three main areas. Some may experience intense reactions to sounds, lights or other sensory input while others may seem not to notice them at all. A cognitive delay may or may not be present.

PDD-NOS, Autism, or Asperger Syndrome?

When PDD-NOS symptoms are considered in the grand scheme of education or daily living, a professional at Emory Autism Center sums up the topic nicely; “For parents and educators, the important thing to focus on is not the specific label a child receives, but what can be done to help the child develop skills in the areas of concern.”


Autism Speaks: Be Informed, Navigating the Spectrum, PDD-NOS,

Centers for Disease Control and Prevention: Diagnostic Criteria, Autism Spectrum Disorders,

Emory Autism Center,

Matson, J. L., Wilkins, J., Smith, K., and Ancona, M. (2008). PDD-NOS Symptoms in Adults with Intellectual Disability: Toward an Empirically Oriented Diagnostic Model. Journal of Autism and Developmental Disorders, 38, 530-537.