What Is a PDD-NOS Diagnosis?

Prior to 2013, there were five separate diagnoses that existed on the autism spectrum. One of them was called pervasive developmental disorder not otherwise specified (PDD-NOS). It is now known as atypical autism, autistic tendencies, or autistic traits in people with the diagnosis.

The five subtypes were folded into a single diagnosis of autism spectrum disorder (ASD) in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) published in 2013. This includes an assessment of the severity of the disorder, as defined by a level of 1, 2, or 3.

This article briefly explains signs and symptoms associated with this ASD diagnosis and how healthcare providers arrive at it. It also offers ideas on how to access quality care and resources for people living with ASD.

Two children working on their homework together

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Symptoms of Atypical Autism

Symptoms of atypical autism tend to be milder than many people with autism experience. As with all types of ASD, atypical autism likely includes difficulties with social communication. The symptoms may include:

  • Atypical or inappropriate social behavior
  • Difficulty with fine or large motor skills, visual or spatial organization, or cognitive skills
  • Delays in speech or language comprehension
  • Difficulty with transitions
  • Deficits in nonverbal and/or verbal communication
  • Increased or decreased sensitivities to taste, sight, sound, smell and/or touch
  • Repetitive or ritualistic behaviors

Children with atypical autism, like those with any form of ASD, can have a wide range of intellectual and verbal abilities. They also may have severe symptoms in one area, perhaps communication, but don't have problems with another symptom like repetitive behaviors.

Diagnostic Challenges

PDD-NOS was essentially a diagnosis of exclusion, a "catchall" term used for people who were on the autism spectrum but didn't fully meet the criteria for another autistic disorder in use at the time. The category was so general and so vague that it told parents, therapists, and teachers very little. A PDD-NOS diagnosis could mean virtually anything.

The new approach introduced in the DSM-5 may offer more insight. One study found that roughly a third (32%) of prior PDD-NOS diagnoses actually fit a diagnosis of social communication disorder.

There is no simple test used to diagnose atypical autism. Healthcare providers assess the skills and behaviors of someone who may have this form of ASD. They rely on parents and teachers who observe a child when deciding on a diagnosis, or similar information when dealing with an adult.


Atypical autism, formerly called PDD-NOS, is often a mild form of autism. Like others living with an ASD diagnosis, people may experience difficulty with speech or skills. Many will have problems with social communication or behavior. An autism evaluation will help to determine the diagnosis and next steps for treatment. Be sure that the healthcare provider you choose has experience with and knowledge of autism spectrum disorders.


Many of the recommended treatments for people with ASD are likely to be very similar, even though each case is unique. Therapy is an important part of treatment and may include:

  • speech therapy
  • occupational therapy
  • physical therapy
  • social skills therapy

In some cases, appropriate medication may be used to help people with specific symptoms of atypical autism. While there is no cure, these treatments may be of great benefit to a child's development, or for an adult with ASD as they move forward with improved quality of life.


People with atypical autism who benefit from treatment will still have challenges in life. It's one reason for why they and the people close to them should have access to books, support groups, professional autism organizations, and other sources of support. These may include:


Since 2013, people who were once diagnosed as having a PDD-NOS autism disorder are now placed in the overall autism spectrum disorder (ASD) category. The PDD-NOS diagnosis is most often called atypical autism, autistic tendencies, or autistic traits in a person. In most cases, the symptoms are mild but include the same social communication and other issues found generally in people with ASD. Therapy and other treatments may be the same as those used to help others with mild forms of ASD.

A Word From Verywell

Life with someone who has an ASD diagnosis is full of challenges. Your healthcare provider can guide you through a process of diagnosing and treating the disease, but there is a wealth of resources to offer you and your loved ones support. Be sure to find ways to connect with others in the ASD community who can help.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Institute of Child Health and Human Development. About Autism.

  2. Centers for Disease Control and Prevention. Diagnostic Criteria.

  3. Kim YS, Fombonne E, Koh YJ, Kim SJ, Cheon KA, Leventhal BL. A comparison of DSM-IV pervasive developmental disorder and DSM-5 autism spectrum disorder prevalence in an epidemiologic sample. J Am Acad Child Adolesc Psychiatry. 2014;53(5):500-8.

Additional Reading

By Lisa Jo Rudy
Lisa Jo Rudy, MDiv, is a writer, advocate, author, and consultant specializing in the field of autism.