Mental Health



Mandy Kloppers

What is Pervasive Developmental Disorder?

Pervasive developmental disorder covers the following disorders.

The pervasive developmental disorders are:
  • Pervasive developmental disorder not otherwise specified (PDD-NOS), which includes atypical autism, and is the most common (47% of diagnoses);
  • Autism, the best-known;
  • Asperger syndrome (9% of autism diagnoses);
  • Rett syndrome; and.
  • Childhood disintegrative disorder (CDD).

Currently, there is no known cure for PDD. There are ways to manage PDD however as well as minimise symptoms. Early intervention can protect intellectual development and improve family stress but the progression of the disroder isn’t completely halted.

People suffering from one of the  disorders under the ‘umbrella’ of pervasive developmental disorder can be high functioning and manage fairly well in daily life. This has mainly been seen in children though and there isn’t much research on adults with PDD. Autism can be seen in varying degrees and it may be hard to understand how Pervasive Developmental Disorder (PDD) differs from another type of autism, Asperger’s syndrome. These two types are the more mild forms of autism, so we will be taking an in-depth look at both to help you better understand them and their differences.

What is Asperger’s Syndrome?

This subtype of autism is considered a “high-functioning” form on the spectrum. Children and adults with this form of autism typically have difficulties with social interactions and understanding social norms. Their range of interests is usually restricted and they may also exhibit repetitive behaviors. According to Autism Speaks, people with Asperger’s may also have developmental delays, uncoordinated motor movements, and general clumsiness.

When comparing Asperger’s syndrome with the more severe forms of autism, these children and adults do not tend to have very significant delays in language or cognitive development. And even though they may have restricted interests, those with this type of autism tend to be very intelligent and specialized within those fields of interest.

The most common behaviors and/or symptoms of Asperger’s syndrome are as follows:

  • Repetitive speech
  • Inappropriate or limited social interactions
  • Nonverbal communication challenges (facial expressions, lack of eye contact, etc.)
  • Overall inability to understand social or emotional issues
  • Obsession with very specific topics
  • Tendency to hold one-sided conversations
  • Awkward mannerisms
  • Possible developmental delays, although not significant

What is Pervasive Developmental Disorder (PDD)?

This subtype of autism may be considered the mildest form on the spectrum. Also known as Pervasive Developmental Disorder-Not Otherwise Specified, this diagnosis became the go-to answer for children and adults who can be classified on the autism spectrum, but do not completely meet the criteria for the other subtypes. According to Autism Speaks, Pervasive Developmental Disorder is “the diagnosis they use for someone who has some but not all characteristics of autism or who has relatively mild symptoms.

Like Asperger’s, those with Pervasive Developmental Disorder tend to have significant challenges when it comes to social and language development. This diagnosis is typically used for people who meet the basic requirements for autism, but do not exhibit the more severe characteristics, like extreme repetitive behaviors, intellectual limitations, or inappropriate mannerisms.

Usually a person is diagnosed with Pervasive Developmental Disorder if they exhibit social and communication challenges, but simply do not exhibit other symptoms of Asperger’s, like obsessions over certain topics, developmental delays, or awkward mannerisms. People with Pervasive Developmental Disorder typically live mostly ordinary lives and are considered the highest-functioning of all autism subtypes, but can have issues relating to people, understanding language, accepting change in surroundings or routines, and dealing with their own emotions.

Pervasive Developmental Disorder – Not Otherwise Specified (NOS)

A PDD-NOS diagnosis is given when a child does not fully meet the criteria for Autism Spectrum Disorder (ASD), Asperger’s Syndrome, Rett Syndrome or Childhood Disintegrative Disorder, but has several of the characteristics.

What are the common features of Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS)?

Children are generally 3 to 4 years old before they exhibit enough symptoms for a diagnosis. There is no set pattern of symptoms or signs in children with PDD-NOS. Children with PDD-NOS may exhibit some of the following features:

Social and Emotional

  • Poor social skills
  • Experience difficulties interacting meaningfully.
  • Reluctant to give eye contact.
  • Appears to lack desire to share activities with others.
  • Prefers to be alone.
  • May want to make friends, but doesn’t know how.
  • Lacks an understanding of issues from another person’s point of view – social empathy.
  • Difficulty understanding that other people have their own beliefs, desires and intentions, which guide their behaviour.
  • Difficulty in taking turns and/or sharing with peers.
  • Difficulty differentiating between familiar and unfamiliar people.
  • May be unintentionally aggressive in an attempt to be social.
  • Treats people as tools or equipment – something to use to open a door, get food, get carried by or lean on.
  • Is limited in their play skills and may become fixated on only playing with specific toys in a particular way.
  • Has poor imaginative play skills.
  • Has low self-esteem

Language and Communication

  • Difficulty understanding or using appropriate forms of communication including verbal language, body language, facial expression, tone of voice and gestures.
  • Difficulty in developing and understanding other forms of communication, such as gestural systems or picture-based systems.
  • Limited or no speech and/or lack typical communicative gestures.
  • As babies, a child with PDD-NOS may not babble or when they do learn words, they exhibit “echolalia” repeating words or phrases over and over again.
  • Children with PDD-NOS often take language literally and do not understand when someone is joking or being sarcastic.
  • Speech may develop to varying degrees but rarely develops to an age-appropriate level of ability.
  • Does not always clearly communicate wants, express concerns or fears, or answer questions reliably.

Sensory Processing

  • May experience great difficulty processing information received from senses (e.g. touch, sound, visual information).
  • Over-sensitive to surroundings and unable to screen out irrelevant stimuli.
  • May appear to ignore some sounds but over-react to other sounds.
  • May focus intently on the small visual details of walls, furniture, objects, prints, pictures or body parts whilst not seeing the whole picture.
  • May show intense interest in light or shiny reflective surfaces (e.g. may filter light through fingers or stare at lights or reflections in glasses or watch water going down the plughole).
  • May explore by smelling or mouthing objects, people and surfaces.

Adaptation to the Environment

  • Finds it very difficult to interpret and process new information.
  • Small changes to routine, activity or surroundings may cause stress and anxiety.
  • Has difficulty coping with change.
  • May avoid strangers or new activities due to fear and anxiety.
  • Develops routines and rituals and may stay involved with them for long periods or be upset if interrupted.
  • Becomes very concerned about doing work perfectly and may become unwilling to attempt work that he/she feels they cannot do perfectly.
  • May want to be in control of situations and may become very successful at manipulating people in order to maintain control.


  • May have learning difficulties.
  • May have poor memory and attention span resulting in difficulty persisting with activities.
  • Requires repetition of instructions or directions and may require time to process before responding or acting.
  • May have difficulty understanding concepts such as turn taking, sharing or how to enter into play situations.

Common difficulties often (but not always) experienced by those with Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS):

  • Poor understanding of the conventions of social interaction.
  • Immature play skills/interests.
  • Resistant to change and very rigid in routine.
  • Poor non-verbal communication.
  • Poor understanding of instructions, questions and/or jokes.
  • Difficulty with fine and gross motor skills.
  • Difficulties accessing the school curriculum.
  • Poor conversational skills and may talk too much or too little.
  • Poor ‘listening’ skills, despite intact hearing.
  • Fails to notice that other people are not interested in what they are saying.
  • Finds it difficult to understand the non-verbal language/cues of others (such as facial expressions, gestures      and/or body movements) or the rules of social behaviour.

Management strategies that support the child with Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS) (at preschool, school and/or home):

  • Routine/planned and structured events.
  • A good knowledge of the child’s strengths, weaknesses, interaction preferences and early signs of distress.
  • Social stories to help teach the child how to act in given situations.
  • Use of visual cues to describe the routine. Visual cues are especially useful when preparing for changes in routine.
  • Extra time/support to transition to school

Occupational Therapy approaches and activities that can support the child with Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS) or their carers include:

  • Expanding abilities: Developing a gradually broadening range of skill areas.
  • Social stories: Providing ideas and education around social story development.
  • School transition: Advocating and professionally supporting the transition to school and liaising with teachers, as required.
  • Behaviour management: Teaching families to use a consistent approach to manage behaviour (e.g. if the child finds that every time they are given a direction, the same response is expected, or that every time they react in a certain way, the same consequence follows, they will learn the appropriate behaviour far more quickly).
  • Structure and routine: Supporting families in providing structure and routine so that the child has clear information about what is going to be happening and what will be expected of the child. This allows the child the chance to prepare for the event and to work out how to behave appropriately.
  • Visual cues can be used at home and preschool/school to reduce anxiety regarding expectations of tasks, to support routine and to introduce new, or a change in, tasks.
  • Sensory processing: Improving sensory processing of the child so they are able to demonstrate their skills across a wider variety of environments.
  • Pre-warning: Giving advance notice of change to routine and instructing parents and teachers of appropriate strategies to implement in other environments.

Speech Therapy approaches and activities that can support the child with Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS) or their carers include:

  • Speech and Language assessment to help the family to understand how the child is processing, understanding, learning and using language and communication.
  • Communication strategies: Providing the family with strategies and techniques to increase and enhance communication with the child.
  • Daily activities: Developing understanding of the environment, routines and language.
  • Developing language: Helping the child to understand and use richer language and to use language more spontaneously.
  • Conversation skills: Developing conversation skills (e.g. back and forth exchange, turn taking).
  • Concept skills: Developing concept skills, especially abstract concepts, such as time (e.g. yesterday, before, after).
  • Visuals can be used to help with understanding and the child’s ability to express their needs, wants, thoughts and ideas.
  • Social skills: Development of social skills (i.e. knowing when, how to use language in social situations).
  • Enhancing verbal and non-verbal communication including natural gestures, speech, signs, pictures and written words.
  • Visual strategies: Using visual information to help a child to understand, organise and plan the routine for the day.
  • Liaising with educational staff regarding the nature of the difficulties and ways to help the child to access the curriculum.

Why should I seek therapy for my child with Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS)?

Diagnosis alone is NOT the solution. It simply opens the door to getting the help that is needed by arming all involved with the relevant information.

The ‘help’ still needs to be provided. The help that is provided (at least from a therapy perspective) will reflect:

  • First and foremost what medical intervention is needed.
  • What the parents/teachers/carers biggest concerns are for the child (i.e. what are the most significant functional challenges).
  • The specific areas that are problematic to the child (which will vary even within children with the same diagnosis).
  • The capacity of the child’s environments to meet the child’s needs.

If left untreated, the child with Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS) may have difficulties with:

  • Following instructions within the home, kindergarten or school environment.
  • Understanding jokes and figurative language during interactions with others, and when watching TV shows and movies and reading books.
  • Managing a full school day due to poor strength and endurance.
  • Participating in sporting activities leading to an inactive lifestyle, increasing the risks of other health related issues such as obesity, diabetes, cardiovascular disease or similar conditions.
  • Self esteem and confidence when they realise their skills do not match their peers.
  • Bullying when others become more aware of the child’s difficulties.
  • Fine motor skills (e.g. writing, drawing and cutting) due to poor core stability, meaning they do not have a strong base to support the use of their arms and hands.
  • Completing self-care tasks (e.g. doing up shoelaces, buttons, zips, using cutlery).
  • Self regulation and behaviour, as the child is unable to regulate themselves appropriately to settle and attend to a task for extended periods of time.
  • Accessing the curriculum because they are unable to attend to tasks long enough to complete assessment criteria.
  • Sleep habits, impacting upon skill development due to fatigue.
  • Anxiety and stress in a variety of situations leading to difficulty reaching their academic potential.
  • Reading/understanding social situations and being perceived as ‘rude’ by others.
  • Social communication, such as eye contact, appropriate distance when talking to someone, turn-taking within a conversation.
  • Academic performance: Developing literacy skills such as reading and writing and coping in the academic environment.
  • Academic assessment: Completing tests, exams and academic tasks in higher education.

More specific implications of not seeking treatment will be influenced by the common difficulties that are most influencing your individual child.

For more information see the relevant fact sheets under areas of concern or refer to the other relevant resources section below.

What does the diagnosis of Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS) really mean for the child?

Diagnoses are used to label a specific set of symptoms that are being experienced by a child.

This label then helps to narrow down and specifically tailor what:

  • Other issues commonly occur simultaneously.
  • Medication might be appropriate.
  • Therapies might help the child (e.g. Medical, Occupational Therapy, Speech Therapy, Psychology).
  • Course of intervention (medical and/or allied health) might be and what outcome might be expected (prognosis).
  • Can be done to help the child.

A diagnosis helps the child and their carers (parents, teachers, health professionals, carers) to:

  • Access information about the relevant cluster of symptoms.
  • Communicate the salient features of the child’s challenges to all people involved in the child’s care.
  • Possibly interpret certain behaviours differently in light of the diagnosis.
  • Obtain information about what can be done to help the child.
  • Determine specifically where and how to help the child.
  • Access funding or services that might not otherwise be accessible.


30 best movies on PDD:  CLICK HERE


Photo by Michał Parzuchowski on Unsp


Pervasive Developmental Disorder – Not Otherwise Specified (PDD- NOS)