Pervasive Developmental Disorder (PDD)

Pervasive developmental disorder (PDD) is an older umbrella term for conditions that affect social interaction, communication and behaviour from early childhood. The American diagnostic manual used it until 2013, when most conditions under it were merged into autism spectrum disorder. If a report or school file says “PDD” or “PDD-NOS”, it means an autism-spectrum diagnosis under the old system.

Also called: pervasive developmental disorders (plural, for the group); PDD-NOS (PDD not otherwise specified); now autism spectrum disorder (ASD), or simply autism.

Types

Under the fourth edition of the manual (DSM-IV), PDD covered five conditions:

Autistic disorder, sometimes called classic autism.
Asperger syndrome: autism without a delay in speech or general learning.
PDD not otherwise specified (PDD-NOS): autistic traits that didn’t fit the other labels fully. This was the most common PDD diagnosis.
Childhood disintegrative disorder: a rare condition in which a child loses skills after a period of ordinary development.
Rett syndrome: a genetic brain disorder, almost always in girls, in which development looks ordinary for 6 to 18 months before language, hand use and coordination are lost. Almost all cases come from changes in one gene, MECP2.

What changed in 2013

The fifth edition (DSM-5), published in May 2013, replaced the first four with a single diagnosis, autism spectrum disorder, graded by how much support a person needs. Rett syndrome was taken out, because it has its own genetic cause. WHO’s ICD-11 made the same move and lists autism spectrum disorder as one condition.

Most people keep their diagnosis under the new rules. In a study of every child aged 7 to 12 in one South Korean community, 99% of those with autistic disorder, 92% with Asperger disorder and 63% with PDD-NOS met the DSM-5 criteria for autism; most of the rest fitted a new label, social communication disorder. A smaller Japanese study found the new criteria could miss some older or more able people, which is why a current assessment matters if an old label is causing confusion.

Signs and symptoms

The signs are the signs of autism. In children they include starting to speak later than others, not responding to their name, using less eye contact and fewer gestures, little pretend play, repetitive movements such as rocking or hand-flapping, very strong interests, distress at changes in routine, and strong reactions, or none, to sounds, lights, textures and foods. Girls may copy other children, stay quiet in hard situations and show fewer repetitive behaviours, so they are missed more often. Signs usually appear in the first three years, though some people aren’t recognised until adulthood.

Treatment

There is no cure, and nothing to cure. Support is matched to the person: speech and language therapy, occupational therapy for sensory needs and daily living, adjustments at school or work, and support for the family. Anxiety and depression are common alongside autism and are treatable; a doctor may prescribe for those, but no medicine treats autism itself. Diets, supplements and “detox” products are not treatments, and some are harmful.

In Nigeria

Older Nigerian reports and school letters still use “PDD”, so parents meet the term without an explanation. Research on autism in Nigeria is thin and services are patchy. Child and adolescent teams at the federal neuropsychiatric hospitals in Yaba and Calabar name autism among the conditions they assess. At one such hospital, prayer houses, traditional healers and patent medicine stores were among the first places families had gone for help. Autism is not caused by vaccines, by parenting or by anything spiritual, and years spent in deliverance instead of speech therapy are years a child doesn’t get back.

PDD vs autism spectrum disorder

They describe the same group of people. PDD is the old heading, used from the 1990s to 2013; autism spectrum disorder is the current one. “Pervasive” meant the differences affect many areas of life, not that they are severe. Asperger syndrome was one PDD and is now part of the spectrum. Rett syndrome is the exception: it is a separate genetic condition.

When to get help

For a child, start with a paediatrician or family doctor, who can refer to a child development or child psychiatry service for a full assessment. If a child is distressed or unsafe, Cece Yara’s free 24-hour child line is 0800 800 8001. Parents can book a licensed therapist for themselves through family and parenting therapy. Adults who were given a PDD label as children, or who recognise themselves now, can ask a psychiatrist or clinical psychologist about an adult assessment; our guide to autism in adults explains what to expect.