1.
INTRODUCTION
The term Pervasive Developmental Disorders was first used
in the 1980s to describe a class of disorders. This class
of disorders has in common the following characteristics:
impairments in social interaction, imaginative activity,
verbal and nonverbal communication skills, and a limited
number of interests and activities that tend to be repetitive.
The
manual used by physicians and mental health professionals
as a guide to diagnosing disorders is the Diagnostic and
Statistical Manual of Mental Disorders (DSM). The DSM was
last revised in 1994. In this latest revision, known as
the DSM-IV, five disorders are identified under the category
of Pervasive Developmental Disorders: (1) Autistic Disorder,
(2) Rett's Disorder, (3) Childhood Disintegrative Disorder,
(4) Asperger's Disorder, and (5) Pervasive Developmental
Disorder Not Otherwise Specified, or PDDNOS.
Many
of the questions parents and education professionals ask
NICHCY have to do with children who have been diagnosed
with "PDD." Doctors are divided on the use of
the term PDD. Many professionals use the term PDD as a short
way of saying PDDNOS. Some doctors, however, are hesitant
to diagnose very young children with a specific type of
PDD, such as Autistic Disorder, and therefore only use the
general category label of PDD. This approach contributes
to the confusion about the term, because the term PDD actually
refers to a category of disorders and is not a diagnostic
label. The appropriate diagnostic label to be used is PDDNOS--Pervasive
Developmental Disorder Not Otherwise Specified--not PDD
(the umbrella category under which PDDNOS is found).
Accordingly,
this Briefing Paper will use the term PDD to refer to the
overall category of Pervasive Developmental Disorders and
the term PDDNOS to refer to the specific disorder, Pervasive
Developmental Disorder Not Otherwise Specified. The majority
of this Briefing Paper will focus on PDDNOS.
All
of the disorders that fall under the category of PDD share,
to some extent, similar characteristics. To understand how
the disorders differ and how they are alike, it's useful
to look at the definition of each disorder. Therefore, before
we begin our discussion of PDDNOS, let us look first at
the definition of the general category PDD and its specific
disorders.
Definition
of the PDD Category and its Five Specific Disorders
All types of PDD are neurological disorders that are usually
evident by age 3. In general, children who have a type of
PDD have difficulty in talking, playing with other children,
and relating to others, including their family.
