Pervasive Developmental Disorder (PDD), sometimes used interchangeably with Autism Spectrum Disorder (ASD), refers to children or adults who have been diagnosed as being on the autism spectrum but do not fully meet the criteria for full-fledged autistic disorder or Asperger syndrome. According to Autism Speaks, PDD is referred to by some health professionals as Subthreshold Autism and is applied to those experiencing some symptoms or mild symptoms of autism.
Diagnosis. The following problems are present with someone who has PDD. Keep in mind that these symptoms can also be an indicator of autistic disorder.
- An impairment in verbal and nonverbal communication
- Restricted, repetitive behaviors
- Lag in language development
- Mild cognitive impairment
Classifications. Someone diagnosed with PDD is usually classified in one of three categories:
- A high-functioning group — About 25 percent of those diagnosed with PDD fall into the high functioning group. Their symptoms mostly overlap with those of Asperger syndrome. In addition, individuals in this group have a lag in language development and mild cognitive impairment, symptoms not prevalent with Asperger's.
- Autistic disorder group — About 25 percent of those diagnosed with PDD show symptoms that closely resemble an autistic disorder but do not fully meet its signs and symptoms.
- Another autistic disorder group — About 50 percent of those diagnosed with PDD "meet all the diagnostic criteria for autistic disorder, but whose stereotypical and repetitive behaviors are noticeably mild," according to Autism Speaks.
Treatment. The key to treating PDD is early diagnosis and intervention. The earlier the disorder is diagnosed and treated, the more likely an individual is to have success in mainstream classrooms in school, as well as at achieving independence and a high quality of life in adulthood. It is, however, never too late to begin behavioral therapy. Treatment for PDD is highly individualized and should begin with an evaluation from a qualified developmental specialist. The specialist will take into account behavioral history, current symptoms, communication patterns, social competence and neuropsychological functioning. Parents of children diagnosed with PDD should pursue an Early Intervention Program for young children and an Individualized Education Plan for a school-age child.