Pervasive developmental disorder

# Overview
The diagnostic category pervasive developmental disorders (PDD), as opposed to specific developmental disorders (SDD), refers to a group of five disorders characterized by delays in the development of multiple basic functions including socialization and communication. The most commonly known PDD is (1) Autism, with the remaining identified as (2) Rett syndrome, (3) Childhood disintegrative disorder, (4) Asperger syndrome, and (5) Pervasive Developmental Disorder Not Otherwise Specified (or PDD-NOS).
Parents may note symptoms of PDD as early as infancy and typically onset is prior to 3 years of age. PDD itself generally does not affect life expectancy.
There is a division among doctors on the use of the term PDD. Many use the term PDD as a short way of saying PDDNOS. Others use the general category label of PDD because they are hesitant to diagnose very young children with a specific type of PDD, such as autism.  Both approaches contribute to confusion about the term, because the term PDD actually refers to a category of disorders and is not a diagnostic label.

# PDD-NOS and terminology
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. To further complicate the issue, PDD-NOS can also be referred to as atypical personality development, atypical PDD, or atypical Autism.

# Symptoms
Symptoms of PDD may include communication problems such as:
- Difficulty using and understanding language
- Difficulty relating to people, objects, and events
- Unusual play with toys and other objects
- Difficulty with changes in routine or familiar surroundings
- Repetitive body movements or behavior patterns

# Types and degrees
Autism, a developmental brain disorder characterized by impaired social interaction and communication skills, and limited range of activities and interests, is the most characteristic and best studied PDD. Other types of PDD include Asperger's syndrome, childhood disintegrative disorder, Rett syndrome, and PDD not otherwise specified (PDD-NOS).
Children with PDD vary widely in abilities, intelligence, and behaviors. Some children do not speak at all, others speak in limited phrases or conversations, and some have relatively normal language development. Repetitive play skills and limited social skills are generally evident as well. Unusual responses to sensory information  loud noises, lights  are also common.

# Diagnosis

## In early childhood
Some clinicians use PDD-NOS as a "temporary" diagnosis for children under the age of 5, when for whatever reason there is a reluctance to diagnose autism. There are several justifications for this: very young children have limited social interaction and communication skills to begin with, therefore it can be tricky to diagnose milder cases of autism in toddlerhood. The unspoken assumption is that by the age of 5, unusual behaviors will either resolve or develop into diagnosable autism. However, some parents view the PDD label as no more than a euphemism for autism spectrum disorders, problematic because this label makes it more difficult to receive aid for Early Childhood Intervention.

# Cure and care
There is no known cure for PDD. Medications are used to address certain behavioral problems; therapy for children with PDD should be specialized according to the child's specific needs.
Some children with PDD benefit from specialized classrooms in which the class size is small and instruction is given on a one-to-one basis. Others function well in standard special education classes or regular classes with support. Early intervention, including appropriate and specialized educational programs and support services play a critical role in improving the outcome of individuals with PDD. PDD is very commonly found in individuals and especially in children with the range of 2 to 5 years of age. These signs can be easily detected within the classroom settings, home, etc.