Pervasive Developmental Disorder-Not Otherwise Specified

shutterstock_175293785Sometimes people do not ‘fit in’ to any of the ASD’s described above. However, they do manifest an impairment in the development of social interaction, or non-verbal or verbal communication skills, or stereotyped behaviors. These behaviors manifested may not meet the criteria for any of the ASD’s due to late onset, or insufficient characteristics specified each ASD. It is said then that the person has Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS).

PDD-NOS is a “sub-threshold” condition in which some features of autism or any other ASD are identified. PDD-NOS is at times referred as “atypical personality development” or “atypical autism”.


People with PDD-NOS have :
• Deficits in social behavior
• Impairment in non-verbal communication
• Deficit in understanding and development of language
• Unusual pattern of behavior

Deficits in social behavior
Children with PDD-NOS have deficits in social behavior but not as severe as that in autism. There may be lack of eye contact but the child may enjoy a tickle or physical contact. The child may have a bonding with parents or familiar adults. However, he/she is unable to build peer relationships and may not be able to cope well in group activities. As they become older people with PDD-NOS may become affectionate but still have issues in managing complex social relationships well.

Impairment in non-verbal communication
People with PDD-NOS may develop instrumental communication in early childhood and require concrete referents for indicating desires. But by middle childhood, they begin to understand other people’s gestures. However, they are still poor in using gestures themselves. They may use some repetitive gestures to denote joy, fear or anger but only the extreme forms of these emotions.

Deficit in understanding and development of language
Those with co-morbidity of intellectual disability may not develop more than a limited understanding of language. Most people are able to understand instructions if given in immediate context and accompanied with gestures. However, comprehension of puns, adages, idioms and phrases is difficult. Echolalia is a common feature in early years. Though echolalia reduces in later childhood there is distinct problem in pronunciation of words. Use of abnormal grammar in spontaneous speech is also often seen.

Unusual patterns of behavior
Like those with autism, persons with PDD-NOS also resist change in the routine. Many have stereotypical behaviors and abnormal attachments to objects and specific behaviours. Hyper or hypo sensitivity to sensory stimuli may be seen in some people with PDD-NOS.

Diagnosis of PDD-NOS is based on the set of criteria given in the DSM for the ASD. When autistic
feature/behaviors are present but do not meet the full criteria of any of the ASD, the diagnosis of
PDD-NOS may be arrived at. This does not indicate that PDD-NOS is a milder than other ASD. It only means that
while a specific ASD diagbostic criteria is not applicable the person still falls within the autistic spectrum.

Children with PDD-NOS require educational program similar to those with other ASD. Decision about placement in mainstream or special class depends on their functioning level. Instructional programs should be based on ABA principles. Speech and language therapy along with occupational and sensory integration therapies should part of the services given to them.

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