Pervasive Developmental Disorders

Pervasive Developmental Disorders (PDD) are also known as Autistic Spectrum Disorders. They include a group of five neurological disorders characterized by developmental delays of basic functions such as the ability to communicate, understand language, and socialize with others including peers and family. The five developmental disorders are:

  • Autistic Disorder
  • Rett’s Disorder
  • Childhood Disintegrative Disorder
  • Asperger’s Disorder
  • Pervasive Developmental Disorders Not Otherwise Specified

Many parents are often confused by the term Pervasive Developmental Disorders when their child is diagnosed. Often this is because a lot of doctors are hesitant to diagnose very young children with a specific PDD, but PDD is not a true diagnosis, but a category that includes all five of the disorders listed above. The official diagnosis in this case should be Pervasive Developmental Disorders Not Otherwise Specified (PDDNOS) which simple means that there is a pervasive developmental disorder present, but the doctor has yet to narrow down which exact disorder it is.

I could write a very long post that tried to cover all of the PDDs, but that would be very long and perhaps confusing, so what I am going to do is post one at a time over the next few days. To understand each PDD it is good to have a definition of the overall disorder and so we will start with PDDNOS.

Pervasive Developmental Disorders Not Otherwise Specified

All PDDs are neurological disorders that are usually evident by the time the child is three years old. They generally have trouble playing with their peers, socializing and relating to others. They also often have stereotyped behavior, interest and activities, inappropriate fascination with objects and often don’t like changes, even small ones. One parent vented her frustration to me saying that it felt like her child was always rejecting her.

Children with PDDNOS either do not fully meet the criteria of the other PDDs or do not have the degree of impairment usually considered suitable to fulfill the diagnosis of the other four disorders. According to the Diagnosis and Statistical Manual of Mental Disorders IV (DSM-IV), this diagnosis should be used “when there is a severe and pervasive impairment in the development of social interaction or verbal and nonverbal communication skills, or when stereotyped behavior, interests, and activities are present, but the criteria are not met for a specific Pervasive Developmental Disorder, Schizophrenia, Schizotypal Personality Disorder, or Avoidant Personality Disorder” (American Psychiatric Association).

In general, children are usually diagnosed with PDDNOS when they have behaviors that are seen in Autism, but doesn’t meet the full diagnostic criteria.

Part of the confusion with PDDs is that the DSM-IV should be used as a guideline for diagnosing PDDS. Many doctors use it as a checklist. There are no clear guidelines for measure severity of symptoms which cause the lines between Autism and PDDNOS to become blurred. Confusion is also added in the fact that some doctors feel that Autistic Disorder only covers those who show extreme symptoms that meet every single criteria for it, while other doctors are comfortable using Autistic Disorder to define those with a broad range of symptoms related to language and social skills. Therefore, it is not uncommon for an individual to be diagnosed by one doctor as having Autistic Disorder and by another as having PDDNOS. There is growing evidence that PDDNOS and Autistic Disorder aren’t actually separate disorders, but are on a continuum which is why the term Autistic Spectrum Disorders is now frequently used to refer to PDDs. Multisystem Developmental Disorders is another term thrown around seldomly, but it is the same as PDDNOS and Autistic Spectrum Disorder.

Causes of PDDNOS

Studies that include behavioral and biological studies all suggest that PDDNOS is caused by neurological abnormalities (problems with the nervous system). However, no specific cause is known. There’s been controversy about childhood vaccinations being responsible for PDDNOS, but no clear evidence or studies have been able to show consistent evidence supporting that.

Symptoms/Signs of PDDNOS

These are some of the symptoms and signs of PDDNOS. Since it is a spectrum disorder, not all children will show the same symptoms, all of the symptoms or have the same intensity of symptoms as other children with PDDNOS.

  • Impairment in Nonverbal Communication
  • Impairment in Understanding Speech
  • Impairment in Speech Development
  • Abnormal Attachments and Behaviors
  • Unusual Responses to Sensory Experiences
  • Disturbance of Movement
  • Resistance to Change
  • Intellectual and Cognitive Deficits

They may also have associated features such as emotional expressions that are flat, excessive or inappropriate to the situation. They may scream, cry or laugh at any time for no apparent reason. They may not be afraid of real dangers such as falling or getting hit by a car, yet be terrified by a specific doll or stuffed animal.


The DSM-IV is only one tool used to help diagnose PDDNOS. Medical assessments, occupational assessments (used to determine how the child’s different senses work together), interviews with the child’s parents, teachers, behavioral rating scales, psychological assessments, educational assessments and direct behavioral observations are some of the many other tools used to help diagnose PDDNOS. There are no specific test such as blood tests, or x-ray exams that can determine if a child has PDDNOS or not.


Treatments for PDDNOS are usually the same used to treat all PDDs, but no one treatment will help all children and often they need to be individualized. Common treatments include:

  • behavior modification
  • structured educational approaches
  • medications
  • speech therapy
  • occupational therapy
  • counseling
  • family counseling
  • psychological treatment
  • facilitated communication
  • Auditory Integrative Therapy
  • Sensory Integrative Therapy
  • Dietary Therapies
The aim is typically to promote more acceptable and appropriate social and communication behavior as well as to minimize negative behaviors such as repetitive behaviors, self-injury, hyperactivity and aggression.

It is also important for parents of children with PDDNOS or any PDD (just like parents of children with any other disorder) to seek out help in the form of parent support groups in order to educate, remember that they are not alone and also to replenish themselves.

I hope that this post on PDDNOS was helpful. I realized halfway through writing this how tough it was going to be to try to cover PDDNOS in one post, partway through I was like, “What was I thinking” but hopefully I’ve laid out a decent basis to start discussing the other four disorders starting with Autistic Disorder tomorrow.

For those of you who want more information I’ve included the names, contact information and web addresses of some organizations below.


Autism Coalition

Autism Patient Center

Autism-PDD Resources Network

Division TEACCH:

Indiana Resource Center for Autism

National Institute of Child Health and
Human Development

Asperger Syndrome Coalition of the United States, Inc. (ASCU.S.)
2020 Pennsylvania Ave., NW, Box 771, Washington, DC 20006
Telephone: 1-866-427-7747
Autism Society of America
7910 Woodmont Avenue, Suite 300
Bethesda, MD 20814
Telephone: 1-800-328-8476

International Rett Syndrome
Association, 9121 Piscataway Road,
Clinton, MD 20735. Telephone:
1-800-818-RETT; (301) 856-3334.

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