Pervasive developmental disorder

The diagnostic category pervasive developmental disorders (PDD), as opposed to specific developmental disorders (SDD), was a group of disorders characterized by delays in the development of multiple basic functions including socialization and communication. It was defined by the Diagnostic and Statistical Manual of Mental Disorders (DSM) (from 1980 to 2013), and the International Classification of Diseases (ICD) (until 2022).

The pervasive developmental disorders included autism, Asperger syndrome, pervasive developmental disorder not otherwise specified (PDD-NOS), childhood disintegrative disorder (CDD), overactive disorder associated with intellectual disability and stereotyped movements, and Rett syndrome. As of the publication of the DSM-5 in 2013, the first four of these disorders are now known collectively as autism spectrum disorder; the last disorder is much rarer, and is sometimes placed on the autism spectrum and sometimes not.

The onset of pervasive developmental disorders occurs during infancy, but a specific condition is usually not identified until the child is around three years old. Parents may begin to question the health of their child when developmental milestones are not met, including age appropriate motor movement and speech production.

There is a division among doctors on the use of the term PDD. Many use the term PDD as a short way of saying PDD-NOS. Others diagnose the general category label of PDD because they are hesitant to diagnose very young children with a specific type of PDD, such as autism. Both approaches contribute to confusion about the term, because the term PDD is intended by its coiners and major bodies to refer to a category of disorders and not be used as a diagnostic label. The fifth edition of the DSM removed PDD as a category of diagnoses, and largely replaced it with ASD and a measure of the relative severity of the condition. The eleventh edition of the ICD also removed the category.

Symptoms of PDD may include behavioral and communication problems such as:

Children with PDD vary widely in abilities, intelligence, and behaviors. Some children do not speak at all, others speak in limited phrases or conversations, and some have relatively normal language development. Repetitive play skills and limited social skills are generally evident. Unusual responses to sensory information—loud noises, lights—are common.

Diagnosis is usually made during early childhood. Individuals who received diagnoses based on the DSM-IV maintain their diagnosis under the autism spectrum disorders. However, an editorial published in the October 2012 issue of American Journal of Psychiatry notes that, while some doctors argue that there is insufficient evidence to support the diagnostic distinction between ASD and PDD, multiple literature reviews found that studies showing significant differences between the two disorders significantly outnumbered those that found no difference.

The World Health Organization's International Classification of Diseases, 10th edition (ICD-10) categorized PDD into five distinct subtypes, each with their own diagnostic criteria. The five subtypes, childhood autism, atypical autism, Rett syndrome, Asperger syndrome and childhood disintegrative disorder, are characterized by abnormalities in social interactions and communication.