About Pervasive developmental disorder (PPD) is an umbrella of behavioral disorders that affects communication, speech, social interaction, and encompasses a repetitive type compulsive behavior. PDD is NOT a diagnosis, it’s a category. What is commonly knows as autism falls under this definition, but there are 5 types of PPDs: Autism Spectrum Disorders (childhood autism & Asperger’s syndrome), childhood disintegrative disorder, Rett’s disease, and PPD NOS – pervasive developmental disorder not otherwise specified.
Childhood autism
Behaviors indicative of childhood autism present themselves before age 3. Children affected by this disorder have poor eye contact, language delay, ignore others, and often seem to be “in their own world.” Children with autism have severe speech, communication, and social delays. The Diagnostic and Statistical Manual of Mental Disorders IV (DSM – IV) criteria for an autism diagnosis are quite specific, but all center on a delay in – or total lack of – development in the areas of communication, social interaction, and emotion. Repetitive gestures are also a hallmark of autism.
Asperger’s syndrome
Children affected by Asperger’s syndrome do have difficulties with appropriate speech and communication, but their language use is less affected than those with childhood autism. Children with Asperger’s may have very high IQ’s, but may lack skills needed to care for themselves or to live independently. These children may lack the ability to understand how they are perceived by others.
Children with Asperger’s may talk repetitively about a topic with no understanding that it is boring to others. Children with Asperger’s may be thought of as simply “odd” or lacking social skills, and they may remain un-diagnosed because of their abilities to compensate with their memory skills or academic abilities.
No clinically significant delays in language or cognitive development are present in these children; the DSM-IV criteria for diagnosis focus on impairment in social interaction and repetitive, restrictive, and stereotyped behavior patterns.
Childhood disintegrative disorder
Children with childhood disintegrative disorder develop normally during the first 3 years of their lives then they seem to develop autistic features and to demonstrate a severe functional impairment, including loss of speech.
Seizures that affect the speech centers of the brain may be a factor in this disorder, so children who exhibit symptoms should be thoroughly evaluated for such seizure activity. Motor skills and social interaction may also be affected in children with this impairment; the DSM-IV offers specific criteria for diagnosis of this condition.
Rett’s disease
Rett’s disease affects only girls; they develop normally until the age of 6 months and then regress. The regression is associated with a small head; the head stops growing from 6 months and on. Girls with this disorder have normal head circumference at birth, however.
Recently there has been a specific chromosomal marker associated with this disorder. The DSM-IV specifies also a loss of purposeful movement of hands as diagnostic criteria.
Pervasive developmental disorder not otherwise specified (PDD NOS)
The term PDD NOS is used to describe children with a severe impairment but who do not fully qualify for other autistic diagnoses. Age of onset or the combination of autistic features differentiates this diagnosis from an autism diagnosis. Children with PPD NOS exhibit behaviors similar to those with autism, but have a lesser degree of impairment.
Resources & References
Read the DSM-IV criteria for these disorders here.