Pervasive Developmental Disorder, Not Otherwise Specified (PDD-NOS)
PSS-NOS is an Autism Spectrum Disorder.
The term or label PDD-NOS is included in DSM-IV (diagnostic manual) to encompass cases where there is marked impairment of social interaction, communication, and/or stereotyped behavior patterns but just falls short of an Autism or similar ASD diagnosis.
Basically PDD-NOS is a diagnosis on the 'subthreshold' of the Autism diagnosis.
Therefore, to understand PDD-NOS, see instead ....
www.rainchild.ie/content/book-page/autism
and
www.rainchild.ie/content/book-page/symptoms-autism-spectrum-disorders
Notes
PDD-NOS is often incorrectly referred to as simply ‘PDD’ The term PDD refers to the class of conditions to which autism belongs. PDD is not itself a diagnosis, while PDD-NOS is a diagnosis of an Autism Spectrum Disorder.
When the DSM-V is published in 2012 it is expected that PDD-NOS will be renamed to ASD-NOS and the term "PDD" will be discarded from terminology completely.
