Five major conditions make up the pervasive developmental disorder diagnosis:
- Autism -- The most well known PDD, autism is a neurological developmental disorder that can affect one in every 150 people [Source: WebMD]. Autistic people have problems with verbal and nonverbal communication and social interaction, and they display excessive repetition or an obsession with narrow interests. A majority are also mentally retarded. Autism does not affect every child the same way, so to that end, autism is also referred to as autism spectrum disorder. This spectrum allows for variances in behavioral patterns and skills in those with autism, from mild to highly debilitating.
- Asperger's syndrome -- This syndrome, named for Viennese pediatrician Hans Asperger, is considered by many medical professionals to be part of the autism spectrum. Children with Asperger's are often high functioning and intelligent, but they can have poor social skills and communication issues. Other typical traits of Asperger's include problems reading body language, understanding humor and creating obsessive routines or interests. Some children with Asperger's may be unusually sensitive to sensory stimuli that other people aren't bothered by, such as lights or noises.
- Childhood disintegrative disorder -- This is a rare condition in which children's skills regress over time. Children with this condition have normal development, but when they're between two and ten, they lose many of their abilities and skills. This can include social and language skills, but it also many include motor skills and other learned functions like bowel and bladder control. Mental retardation is a high possibility in children with this disorder.
- Rett's syndrome -- This is another rare disorder that affects girls only, because it's caused by a gene mutation on the X chromosome. Boys who are born with this syndrome die at a very young age because the disease affects them more severely. A girl with Rett's develops normally, but the syndrome kicks in when they're between six and 18 months old. Rett's attacks girls both physically and mentally. Language skills deteriorate until the girl can no longer speak, and sufferers also lose muscle tone and coordination, walk stiffly, and lose meaningful use of their hands. They may also experience seizures.
- Pervasive developmental disorder not otherwise specified (PDDNOS) -- PDDNOS is a condition similar to autism in that children may have communicative or sensory impairment, but they don't develop other marked characteristics of autism. Children with PDDNOS are generally more social than children with autism.
Next, we'll look at how you can see the symptoms of PDD.