Special Advice: A look at a non-specific developmental disorder

Do not stare or turn away when you meet a child or a person with special needs. Respond to them as you would to anyone else. Every fortnight, we bring you general information on special conditions, backed by expert knowledge, to help you understand the people with these conditions better. We hope it benefits you or someone you know


PDDNOS is a neurological abnormality for which no specific cause has been identified yet


We continue from where we left off in our last article on pervasive developmental disorders (PDD) by discussing the fifth disorder under its umbrella – Pervasive Development Disorder Not Otherwise Specified (PDDNOS).

Children with PDDNOS either do not fully meet the criteria of symptoms clinicians use to diagnose any of the four specific types of PDD mentioned earlier and/or do not have the degree of impairment described in any of the four specific types of PDD.

According to the Diagnostic Statistical Manual – IV (DSM-IV), this category should be used "when there is a severe and pervasive impairment in the development of social interaction or verbal and non-verbal communication skills, or when stereotyped behaviour, 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."

Despite the DSM-IV concept of Autistic Disorder and PDDNOS being two distinct types of PDD, there is clinical evidence suggesting that Autistic Disorder and PDDNOS are on a continuum – that is an individual with Autistic Disorder can improve and be rediagnosed as having PDDNOS, or a young child can begin with PDDNOS and develop more autistic features, and be rediagnosed as having Autistic Disorder.

To add to the list of labels that parents, teachers and others may encounter, a new classification system was recently developed by Zero To Three: National Center for Infants, Toddlers, and Families (1994). Under this system, called the Diagnostic Classification of Mental Health and Developmental Disorders of Infancy and Early Childhood, the term Multisystem Developmental Disorder, or MSDD, is used to describe pervasive developmental disorders.

However, amidst all this confusion, it is very important to remember that, regardless of whether a child's diagnostic label is autism, PDDNOS, or MSDD, his or her treatment is similar.

Cause of PDDNOS

Both behavioural and biological studies have generated sufficient evidence to suggest that PDDNOS is caused by a neurological abnormality. However, no specific cause has been identified.

Generally, children are three to four years old before they exhibit enough symptoms for parents to seek a diagnosis. There is no set pattern of symptoms and signs in children with PDDNOS. All the behavioural patterns described are common in these children, but a child seldom displays all them at one time. Because of the possibility that PDDNOS and Autistic Disorder are on a continuum, many clinical features described in the following section are very similar to those being described in the literature for Autistic Disorder.

Deficits in social behaviour: Some infants with PDDNOS tend to avoid eye contact and demonstrate little interest in the human voice. They may seem indifferent to affection and seldom show facial responsiveness. As a result, parents often think the child is deaf. In children with fewer delays, lack of social responsiveness may not be obvious until well into the second or third year of life. They do not develop typical attachment behaviour, and there may seem to be a failure to bond. Many such children show a lack of interest in being with or playing with other children. They may even actively avoid other children.

In middle childhood, such children may develop a greater awareness or attachment to parents and other familiar adults. However, social difficulties continue. They still have problems with group games and forming peer relationships and they still have difficulty understanding the complexity of social relationships. Some individuals with less severe impairments may have a desire for friendships. Generally, they are able to show joy, fear or anger, but only in extremes. They often do not use facial expressions that ordinarily show subtle emotion.

Impairment in understanding speech: Comprehension of speech in children with PDDNOS is impaired to varying degrees, depending on where the child is within the wide spectrum of PDDNOS. Individuals with PDDNOS who also have cognitive delays may never develop more than a limited understanding of speech. When impairment is mild, only the comprehension of subtle or abstract meanings may be affected. Humour, sarcasm, and common sayings (e.g. "it's raining cats and dogs") can be confusing for individuals with even very mild PDDNOS.

Impairment in speech development: When the child develops speech, he or she often exhibits abnormalities. Echolalia (seemingly meaningless repetition of words or phrases) may be the only kind of speech some children acquire. Though echolalic speech might be produced quite accurately, the child may have limited comprehension of the meaning. The actual production of speech may be impaired. The child's speech may be like that of a robot, characterised by a monotonous, flat delivery with little change in pitch, change of emphasis or emotional expression.

Problems of pronunciation are common while the children are younger, but often diminish as they get older. Abnormal grammar is frequently present in their spontaneous speech. Words of similar sound or related meaning may be muddled, some objects may be labelled by their use and new words may be coined and prepositions, conjunctions, and pronouns may be dropped from phrases or used incorrectly.

Unusual patterns of behaviour: This takes several forms. Many children are upset by changes in familiar environment. Ritualistic or compulsive behaviours are commonly present. These include an insistence on eating particular foods or repetitive acts, such as hand flapping or finger mannerisms.

Some children develop odd preoccupations like memorising weather information, state capitals, or birth dates of family members. Some children develop intense attachments to odd objects, such as pipe cleaners, batteries or film canisters. Some children may have a preoccupation with certain features of favoured objects such as their texture, taste, smell or shape.

Associated features: The emotional expression of some children with the condition may be flattened, excessive, or inappropriate to the situation. For no obvious reason, they may scream or sob inconsolably one time, yet giggle and laugh hysterically another time. Real dangers, such as moving vehicles or heights, may be ignored, yet the same child might seem frightened of a harmless object, such as a stuffed animal.

Take the case of three-year old Tom. He wasn't talking and didn't seem to want to play with his sister. At day care, Tom wouldn't join in any activities with the other kids, but he really enjoyed playing with water. After about a year of expressing concern to their paediatrician, Tom's parents finally obtained a referral to a develo