Atypical Autism: Traits And Symptoms

Updated January 02, 2019

Atypical autism, which is also commonly known as Pervasive Development Disorder - Not Otherwise Specified (PDD-NOS), is a sub-type of autism that can affect both children and adults. While diagnoses are now confined to autism spectrum disorder (ASD) as of the DSM-5, the traits of atypical autism can still be recognized. This article will discuss the signs of this unique form of autism and the treatment methods that are available.

What Is Atypical Autism?

The introduction to this article briefly mentioned that atypical autism is also referred to as Pervasive Development Disorder - Not Otherwise Specified (PDD-NOS). While the name of this condition may sound technical, it can be explained in layman's terms.

PDD-NOS refers to the state of having traits on the autism spectrum but does not meet the specifications to be diagnosed with Asperger's Syndrome, or another ASD.


It can also indicate that a person has features or attributes of the autism spectrum, but the symptoms are mild. He or she may also exhibit strong symptoms in one area, but no signs in another. For instance, a person's social skills may be severely impacted, but there may be no repetitive behaviors [1]. One's strength may be another person's shortcoming.

Atypical Autism Symptoms

While it's been established that the signs of PDD-NOS can vary from person to person, research shows that individuals, children mainly, can fit into one of these three groups [2]:

  • 24 percent could be placed in a high-functioning group with transient language delay and cognitive impairment
  • Another 24 percent resembled cases of classic autism, but could not meet the full criteria for diagnosis
  • 52 percent could not be diagnosed with autism, because of the lack of stereotyped traits and behaviors

Despite there being a significant variation between possible patients of PDD-NOS, there are general features that people can be on the lookout for. These traits can include [1]:

  • A delay in social and communication skills and language use
  • An inability or difficulty in relating to others
  • Challenges to adapting to new routines or environments
  • Repetitive behaviors and movements

The atypical autism symptoms in adults are not any different than what has been observed in children. However, late age of onset could be an indicator of PDD-NOS.

Is It Any Easier?

Not all cases of atypical autism are mild. Even some people who have mostly tame symptoms may struggle severely in a single area which can lead to challenges in life.

It is shown that people with PDD-NOS may not integrate any better than those who may have a more severe case on the autism spectrum because of their communication issues.

One Norwegian study observed 74 children with autistic disorder (AD) and another 39 with PDD-NOS for 17 to 34 years to measure the adult outcomes in these conditions in regards to disability pensions, marital status, criminality, and mortality. The findings were that [3]:

  • There was a lower rate of disability pensions for the PDD-NOS group in comparison to the AD group
  • Nearly all members of both groups were unmarried
  • 3 percent of those with autistic disorder and 13 percent with PDD-NOS had been convicted of a crime ranging from aggression, threats, vandalism, and illegal drugs
  • There were comparable statistics for mortality rates: 1 male in each group and one female in the AD group had passed away by follow-up.

The reason that there were fewer disability pensions for those with PDD-NOS is mostly that of better psychosocial functioning in comparison to those with autistic disorder. However, the other statistics show that despite this, the hardships are mostly the same.

Is atypical autism in adults less demanding than other conditions on the autism spectrum? Not necessarily, and treatment is essential no matter the degree of severity.

How Atypical Autism Is Treated


Like all forms of autism spectrum disorder, atypical autism, or PDD-NOS is primarily treated by the use of different types of therapies. These methods can include:

  • Speech Therapy - a therapist in this field will work with an individual to improve their speech and language skills. This kind of therapy can benefit both verbal and non-verbal patients.
  • Occupational Therapy - Practitioners will help develop a patient's handwriting and daily life skills. They will also incorporate sensory integration.
  • Social Skills Therapy - Either a speech or occupational therapist can administer this type of therapy. While similar to speech therapy, this type focuses on developing a patient's social interaction with others.
  • Physical Therapy - Utilizing a social setting, a therapist in this area will work on a patient's motor patterns.

It's important to note that the earliest intervention possible has the highest chance for a better prognosis. If caught early, patients can learn the skills that they need to succeed throughout their lives.

This detail does not mean that adults cannot get better though. By utilizing the treatments shown above, older patients have demonstrated improvement. Some have even developed coping skills on their own.

The programs will need to be tailored to adults, however, and currently, the number of services for adults are being overshadowed by ones for children. Services for adults are still in its infancy, which is a reason why early treatment is optimal [4]

If you have any questions about therapy, or if you want information on how to receive services for you or someone else, counselors and therapists at are available to assist you. Our advice section can also be of use to you and may provide some insight to some of your inquiries.

For medication, there may be some approved and non-approved drug treatments for atypical autism symptoms. For example, the FDA has approved the antipsychotic drugs risperidone and aripiprazole to address irritability in patients with autism spectrum disorder [4]. It can also reduce aggression and self-injury.

Additionally, while not approved, it is common for people with autism spectrum disorder to be prescribed sleep aids, anti-depressants, and stimulants to treat the comorbid conditions, which can include [4]:

  • Insomnia
  • Obsessive-Compulsive Disorder (OCD)
  • Attention Deficit Hyperactivity Disorder (ADHD)

Medication is usually not the main course of treatment because of the side effects that are involved with prescription drugs. These adverse effects lead to drugs being reserved for severe cases and make the various therapeutic methods the primary choice.

As always, consult with a psychiatrist or a specialist in autism spectrum disorders before taking any medication. A practitioner will be able to answer whether or not this is the right choice and can provide you with further information regarding dosages and side effects.

Summary And Conclusion


Atypical autism, or Pervasive Development Disorder - Not Otherwise Specified (PDD-NOS), in the psychiatric literature contrasts with other conditions on the autism spectrum in that individuals cannot be placed in one single group or diagnosis. This is what makes it atypical.

People with PDD-NOS can be categorized into three different categories based on the degree of disability. Regardless of an individual's degree of functionality, their symptoms are usually mild in more than one area, and this is why a strict diagnosis could not be made.

However, as of 2013 and the addition of the DSM-5, a ruling of atypical autism is no longer possible either. This version combines previous conditions, such as PDD-NOS, into a single category known as autism spectrum disorder.

Regardless of diagnoses and categorization, we know that patients may have mild traits. Others may struggle immensely in one area but have no symptoms in others. There is no test for atypical autism specifically, but this goes hand-in-hand with the overall complexity that autism spectrum disorder brings. For this, the Autism Spectrum Quotient test (AQ) would be appropriate.

Even if atypical autism tends to display more tameness, this does not signify that patients have a more comfortable life than those with more prominent traits on the autism spectrum.

No matter the variation between individuals, patients who are affected by autism spectrum disorder to some degree or another benefit from the same general treatments.

Participating in therapy has the most potential for people, especially if someone is diagnosed early on. Usually, this will be some form of speech, occupational, physical, and social skills therapy to help people develop the skills that they need in life.


Other than allowing more time for growth and improvement, one reason why it is best to receive treatment early is that there is a lack of adult programs in comparison to ones for younger people. Even though this is the case, adults can still improve once they have access to the resources that they need.

By visiting, you will be able to connect with qualified counselors and therapists who can help answer your questions. If you do not know where to begin treatment, this would be an excellent starting point for anyone.

Despite the changes in the DSM-5, we can still apply what we have learned about atypical autism traits in the past. Condensing what we've previously known into a single autism spectrum disorder diagnosis is better in the long run because we know that two people with ASD are not exactly alike; there is a great deal of diversity.

Rather than having up to five different possible diagnoses, we can now focus on just one and the treatment for it.


  1. PDD-NOS. (2013, December 10). Retrieved from
  2. Walker, D. R., Thompson, A., Zwaigenbaum, L., Goldberg, J., Bryson, S. E., Mahoney, W. J.,. .Szatmari, P. (2004). Specifying PDD-NOS: A Comparison of PDD-NOS, Asperger Syndrome, and Autism. Journal of the American Academy of Child & Adolescent Psychiatry, 43(2), 172-180. doi:10.1097/00004583-200402000-00012
  3. Mordre, M., Groholt, B., Knudsen, A. K., Sponheim, E., Mykletun, A., & Myhre, A. M. (2011). Is Long-Term Prognosis for Pervasive Developmental Disorder Not Otherwise Specified Different from Prognosis for Autistic Disorder? Findings from a 30-Year Follow-Up Study. Journal of Autism and Developmental Disorders, 42(6), 920-928. doi:10.1007/s10803-011-1319-5
  4. Murphy, C., Wilson, C. E., Robertson, D. M., Ecker, C., Daly, E. M., Hammond, N., . . . Mcalonan, G. M. (2016). Autism spectrum disorder in adults: Diagnosis, management, and health services development. Neuropsychiatric Disease and Treatment, Volume 12, 1669-1686. doi:10.2147/ndt.s65455

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