Excerpt from Pervasive Developmental Disorder: Asperger Syndrome

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Background

Asperger disorder is a form of pervasive developmental disorder characterized by persistent impairment in social interactions, repetitive behavior patterns, and restricted interests. Unlike what is seen in autistic disorder, no significant aberrations or delay occurs in language development or cognitive development. Asperger disorder is generally evident in children older than 3 years and occurs more often in boys.

Children with this disorder often exhibit a limited capacity for spontaneous social interactions, a failure to develop friendships, and a limited number of intense and highly focused interests. Although some people with Asperger disorder may have certain communication problems, including poor nonverbal communication and pedantic speech, many individuals have good cognitive and verbal skills. Bowler and colleagues have reported that, although people with Asperger disorder have fewer memories, the experiences of remembering are qualitatively similar in people with Asperger disorder compared with healthy control subjects.¹ Physical symptoms may include early childhood motor delays, clumsiness, fine motor difficulty, gait anomalies, and odd movements.

Individuals with Asperger disorder have normal or even superior intelligence and may make great intellectual contributions while demonstrating social insensitivity or even apparent indifference toward loved ones. Published case reports of individuals with Asperger disorder suggest an association with the capacity to accomplish cutting-edge research in computer science, mathematics, and physics. Although the deficits manifested by those with Asperger disorder are often debilitating, many individuals experience positive outcomes, especially those who excel in areas not dependent on social interaction.

Persons with Asperger disorder have exhibited outstanding skills in mathematics, music, and computer sciences. Many are highly creative, and many prominent individuals demonstrate traits suggesting Asperger syndrome. For example, biographers describe Albert Einstein as a person with highly developed mathematical skills who was unaware of social norms and insensitive to the emotional needs of family and friends.

Although normal language and cognitive development differentiate Asperger disorder from other developmental disorders, the severe social impairment associated with this condition overlaps with disorders such as high-functioning autism (HFA). De Spiegeleer and Appelboom (2007) have pointed out that Asperger syndrome is an autism spectrum disorder.² For clinical management purposes, Asperger disorder and HFA may be considered together. Impaired social skills are associated with several other conditions (eg, developmental learning disability of the right hemisphere, nonverbal learning disability, schizoid personality disorder, semantic-pragmatic processing disorder, social-emotional learning disabilities).

For further information about conditions characterized by social impairments, restricted interests, and mental retardation, see Pervasive Developmental Disorder: Autism.

Pathophysiology

The pathophysiology of Asperger disorder is unknown. Some individuals with Asperger disorder have a history of problems in the prenatal and neonatal periods and during delivery. The relationship between obstetric complications and Asperger disorder is unclear. Events in early development may play a role in the pathogenesis of Asperger disorder.

Neuroimaging of individuals with Asperger disorder and related conditions is described in PET Scanning in Autism Spectrum Disorders, an article that also includes hypotheses about the possible pathophysiology of Asperger disorder.

People with Asperger disorder demonstrate problems analyzing configurations. These deficits likely contribute to problems in facial recognition in people with Asperger disorder.³ Gaigg and Bowler (2007) hypothesize that impairments in the connections between the amygdala and associated structures of the brain may play a role in the pathogenesis of the symptoms of Asperger disorder.⁴

Frequency

United States

Because of the divergent diagnostic criteria used in the United States and Canada, estimates of Asperger disorder frequency widely vary. Various studies indicate rates ranging from 1 case in 250-10,000 children. Additional epidemiologic studies are needed, using widely accepted criteria and a screening instrument that targets these criteria.

International

A population study in Sweden estimates the prevalence of Asperger disorder as 1 case in 300 children. Although this estimate is convincing for Sweden, the findings may not apply elsewhere because they are based on a homogeneous population. Extrapolating from this study, Asperger disorder may be more common than clinicians once thought; pediatricians, family physicians, general practitioners, and other health professionals may underdiagnose this disorder.

Mortality/Morbidity

Individuals with Asperger disorder appear to have normal lifespans; however, they seem to endure an increased prevalence of comorbid psychiatric maladies (eg, depression, mood disorders, obsessive-compulsive disorder, Tourette disorder).

Race

Asperger disorder has no racial predilection.

Sex

The estimated male-to-female ratio is approximately 4:1.

Age

Asperger disorder is commonly diagnosed in the early school years and less frequently during early childhood or even adulthood.

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