Pervasive Developmental Disorder is a description that requires that there is an impairment is social interaction. However, this impairment presents differently in each individual. It can include non-verbal communication/social behaviors (eye contact, facial expressions, gestures, etc.), ability/willingness to speak and share about themselves, and the skill with which they are able to interact with others. Additionally, there are also delays or abnormal behaviors that occur in other areas. These may include communication, and restriction of behaviors or repetitive behaviors. It is rare for two children to present alike.

The Categories of Pervasive Developmental Disorders (PDD) include Autistic Disorder, Asperger Syndrome, Rett Syndrome, Childhood Disintegrative Disorder, and Pervasive Developmental Disorder NOS.

A brief description of these categories follows:

Autism is the most well known of the PDD’s, and must have a number of different symptoms across three different categories: a minimum of two social deficits, one communication deficit, and one restrictive/repetitive behavior. Additionally, they must appear before age 3. Most have a language delay in early childhood, but those who are higher functioning may not. The cognitive functioning levels of those with Autistic disorder range from severe mental retardation to above-averge or superior.

Aspergers Sundrome is characterized by having normal or near-normal formal language abilities (such as vocabulary), coupled with social difficulties. These might include problems with social language, social awkwardness, problems with nonverbal expressiveness, idiosyncratic interests, and motor clumsiness. It is also more common than Autism. Current research is debating whether there is a difference between high-functioning Autism and Aspergers Syndrome.

Retts Syndrome is a progressive deterioration of functioning, and has only been reported in females. Development must have been normal through pregnancy and the first 5 months, with a normal head circumference for this diagnosis to be considered. Development is normal for the first 5 to 28 months, after which there is a period of decelerated head growth lasting up to 48 months of age. This is accompanied by a porogressive loss of motor coordination followed by cognitive skills. Social engagement is also lost, but social interaction often develops later. It is associated with severe to profound mental retardation.

Childhood Disintegrative Disorder is shown through the appropriate development for the first two years, then a significant loss of skills in at least two areas: expressive or receptive language; social or adaptive skills; bowel or bladder control; play; and/or mor skills. The child must also show impairments in two of the followings: social, communication and/or repetitive/restricted behavior. It normally occurs between 3 and 4 years, although it can occur anytime before 10 years.

Pervasive Developmental Disorder Not Otherwise Specified (NOS) is also referred to as atypical autism. The diagnosis is given when the child demonstrates clinically signficant impairment in social interaction and communication and restricted/repetitive behaviors, but does not meet any other diagnosis. This may be because of too few symptoms or because the symptom does not have the severity required for the diagnosis.