eMedicine Specialties > Pediatrics: Developmental and Behavioral > Medical Topics

Pervasive Developmental Disorder

Author: Sufen Chiu, MD, PhD, Assistant Clinical Professor (Volunteer Faculty), University of California Davis Medical School; Consulting Staff, Child and Adolescent Psychiatry of Sacramento County; Consulting Staff, Sutter Center for Psychiatry; Consulting Staff, Transcultural Wellness Center
Coauthor(s): Randi Jenssen Hagerman, MD, FAAP, Professor of Pediatrics, Medical Director MIND Institute, Endowed Chair in Fragile X Research, Division of Developmental/Behavioral Pediatrics, University of California Davis Medical Center; Henrietta Leonard, MD, Program Director, Child and Adolescent Psychiatry, Professor of Psychiatry and Human Development, Division of Child and Adolescent Psychiatry, Rhode Island Hospital and Brown University
Contributor Information and Disclosures

Updated: Mar 26, 2008

Introduction

Background

Pervasive developmental disorders (PDDs) include a spectrum of behavioral problems commonly associated with autism. The Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) includes autism, Rett syndrome, childhood disintegration, Asperger syndrome, and PDD not otherwise specified under the spectrum of PDD.¹ These individual disorders are discussed briefly in this article. For detailed reviews of each, see the eMedicine articles listed above.

The most notable behavioral problems arise in social interaction and communication. Other problematic areas include stereotyped behaviors, restrictive interests or activities, and cognitive deficits. Autistic disorder in its most severe presentation may describe a child aged 3 years who presents with no expressive language, seeking comfort from parents in atypical ways, with pervasive hand flapping, no eye contact, and battles over toilet training. In the mildest presentation, PDD not otherwise specified may be used to describe a child aged 9 years with poor peer interactions and normal verbal and nonverbal intelligence. This child's preoccupation with one of a few restricted interests even tires the patience of typically developing peers with similar interests.

Pathophysiology

The underlying pathophysiology of PDD is under investigation. Current research implicates several CNS systems at different levels. For example, at the molecular level, the type of serotonin-transporter gene promoter may modulate the severity of PDD. Recent data suggest a role for immune system. At the neuroanatomic level, preliminary brain imaging studies have shown differences.² No single anomaly has been demonstrated reliably because of differences between studies related to intelligence quotient (IQ), medication exposure, age of the patient sample, and methods for case ascertainment (low vs high functioning, autistic disorder vs Asperger disorder).

Children with PDD may have other specific cognitive deficits, including central auditory processing problems, which imply distorted pathways between hearing and cortical processing. They may also have specific cognitive strengths. In isolated cases, these special cognitive talents lead to these individuals being labeled savants.

Frequency

United States

A survey of existing literature by Fombonne in 2003 indicated that the current rates for PDD are 30-60 cases per 10,000 population for all forms of PDD, 2.5 cases for 10,000 population for Asperger disorder, and 0.2 case per 10,000 population for childhood disintegrative disorder.³ Fombonne attributes the increase in prevalences over time to changes in case definitions and to improved awareness. Available surveys lack sufficient proof to support an increase in the prevalence of PDD for other reasons.

International

No evidence suggests that international prevalence of the disease differs from prevalence in the United States.

Mortality/Morbidity

• Obsessive-compulsive disorder (OCD) and attention deficit hyperactivity disorder (ADHD) are often comorbid psychiatric symptoms that some clinicians label separately, whereas others include them as part of the presentation of PDD. Regardless of the approach, these symptoms of OCD and ADHD may be disabling and require treatment with standard approaches that include but that are not limited to medications and behavioral therapy.
• Aggression is a symptom not specific to any particular psychiatric disorder. The etiologies are broad and include constipation, depression, anxiety, psychosis, or adjustment disorder. Treatment requires clarification of etiology to help select medications and other appropriate therapies.
• Psychosis is often the most difficult symptom to elicit and diagnose appropriately in children with PDD. Not long ago, children with PDD were often identified as having childhood-onset schizophrenia. The DSM establishes criteria that clearly distinguish PDD from childhood-onset schizophrenia. The DSM recognizes that children with PDD may develop psychotic disorders if they present with clear evidence of auditory, visual, tactile, and/or olfactory hallucinations. Nevertheless, determining whether a child has PDD or psychosis may be difficult during the initial clinical evaluation. For example, individuals with mental retardation may present with cognitive disorganization; they may link irrelevant thoughts together or have beliefs in magical beings, even as adults. These findings are considered normal in a person with intellectual disability.

Race

Race has not been implicated as a risk factor for PDD.

Sex

Sex bias for PDD is significant.

• Autism and PDD not otherwise specified may affect boys up to 5 times more often than girls.
• In Asperger syndrome, boys may be affected 10 times more often than girls.
• Only in Rett syndrome are girls more commonly affected than boys; Rett syndrome is rarely diagnosed in boys. However, new molecular testing for Rett syndrome is identifying more affected boys than previously reported.

Age

Autistic disorder carries an onset criterion; evidence of the disorder must be present by age 3 years. Rett syndrome and childhood disintegrative disorder are also usually apparent by age 3 years. Regression, or the loss of developmental milestones, remains controversial in autistic disorder. The loss of developmental milestones traditionally suggested Rett syndrome or childhood disintegrative disorder. However, growing evidence suggests that regression may be an important subtype of autistic disorder.

Clinical

History

Reactive attachment disorder is an important differential diagnostic entity for pervasive developmental disorder (PDD). If any child has a clinically significant history of physical or emotional deprivation, a PDD diagnosis should be deferred until the child has had an opportunity to recover in an enriched environment. Any history of deficiencies in the following areas is an indication for an evaluation for PDD.

• Language development
  • Delay - Suggests autism or PDD not otherwise specified
  • Regression⁴ - Consistent with Rett disorder or childhood disintegrative disorder but may also be an important subtype of autistic disorder
  • Normal language development - Diagnostic feature of Asperger disorder
• Poor social interaction
  • Social isolation
  • Poor eye contact
  • Attachment to unusual objects
  • Overdeveloped circumscribed interests in odd or specific topics
  • Inability to engage in imaginative play
• Stereotyped behaviors
  • Hand flapping
  • Self-injurious behavior (eg, head banging)
  • Difficulty making a transition between activities
• Sensory integration difficulties
  • Oral aversion to certain textures or colors
  • Olfactory aversion
  • Tactile aversion to certain fabrics (eg, tags on clothing, position of socks)
  • Auditory aversion to loud noises or types of music

Physical

Physical examination findings are usually normal, but the evaluation should be thorough to exclude genetic or metabolic disorders.⁶ Children with PDD often have no physical findings. The most important exception is Rett disorder; almost all patients who present with this disorder have the characteristic findings of hand-wringing, hyperventilation, or both.

Causes

Identified organic disorders that occur with PDD include epilepsy (the most common medical condition associated with PDD), cerebral palsy, fragile X syndrome (see Media file 1), tuberous sclerosis, phenylketonuria, neurofibromatosis, Down syndrome, and congenital rubella. Roughly 10% of patients with PDD present with a known medical disorder. Seizures are the most frequent comorbidity.

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