In general, pervasive developmental disorders are characterized by impaired social interaction and communication skills, and a limited range of activities and interests. Associated behavioral and emotional difficulties are often present as well. Our medical diagnostic system recognizes five distinct types: 1) autism, 2) Asperger’s disorder, 3) Rhett’s disorder, 4) childhood disintegration disorder, and 5) pervasive developmental disorder not otherwise specified. However, multi-complex pervasive disorder is a category that is recently under investigation.
Other disorders can mimic symptoms or “look like” autism, especially at a young age. For instance language disorders, nonverbal learning disorder, developmental dyspraxia, attention-deficit, and anxiety to name a few and resemble the symptoms of autism.
An unspecified or not otherwise specified pervasive developmental disorder (PDD, NOS) is used when a child exhibits some traits/symptoms of autism or Asperger’s disorder, but not enough to make a diagnosis. On occasion, children may exhibit some unusual or bizarre symptoms that is not explained by another developmental, psychiatric, or neurological disorders (e.g., significant self-harming, breath-holding spells), though language and peer-relationships maybe fairly normal. Although autism and Asperger’s disorder is present at a very young age, it is often difficult to make a specific diagnosis in children 3 years or less, especially if they are seemingly higher functioning. Thus, a diagnosis of pervasive developmental disorder, not otherwise specified is used to describe the child’s current symptoms. As they age, their symptoms may become more clear or defined, and then a diagnosis of autism or Asperger’s disorder, or another syndrome can be made. However, this is not always the case, and children may only exhibit a few traits of autism throughout their lifetime. Some professionals consider this diagnosis as atypical autism.