What is Asperger's Syndrome?
Asperger's syndrome is a former diagnostic category within autism spectrum disorders characterized by social communication difficulties and restricted interests, but without early language delays or intellectual disability—it is now subsumed under the single diagnosis of Autism Spectrum Disorder (ASD) in DSM-5. 1
Historical Context and Current Classification
Asperger's disorder was first described in 1944 but not officially recognized until DSM-IV. 1 The key distinguishing feature was that individuals with Asperger's disorder did not present with delays in language acquisition or unusual behaviors during the first years of life, so parents often had no early developmental concerns. 1
As of DSM-5 (2013), Asperger's disorder no longer exists as a separate diagnosis. 1 The various pervasive developmental disorders were consolidated into a single diagnosis of Autism Spectrum Disorder because there was insufficient evidence to support reliable and replicable diagnostic differences among the subcategories. 1
Core Clinical Features (Historical Definition)
Social Communication Pattern
- Children were precocious in learning to talk but then communicated in a formal, pedantic, one-sided manner, often fixated on circumscribed topics of interest. 1
- Social difficulties arose from this idiosyncratic, one-sided social interaction style rather than from lack of language ability. 1
Cognitive Profile
- No intellectual disability was present (distinguishing it from classic autism). 1
- Language development proceeded normally or even advanced in early childhood. 1
Behavioral Characteristics
- Restricted and repetitive patterns of behaviors and interests were present, similar to other autism spectrum conditions. 1
- Social interaction and communication deficits manifested despite intact language skills. 1
Prognosis and Outcomes
The outcome in Asperger's disorder generally appeared better than that for classic autism, although this may relate to better cognitive and verbal abilities rather than fundamental differences in the condition itself. 1 This observation contributed to the decision to view autism as a spectrum rather than discrete categories.
Current Diagnostic Approach
Under DSM-5, individuals previously diagnosed with Asperger's syndrome now receive a diagnosis of Autism Spectrum Disorder with specifiers indicating: 1
- No intellectual impairment (specifier)
- No language impairment (specifier)
- Severity level for social communication deficits and restricted/repetitive behaviors
The American Academy of Child and Adolescent Psychiatry emphasizes that ASD is now defined by two essential symptom domains: social communication/interaction deficits and restricted/repetitive behaviors, with most individuals having average to above-average intellectual ability. 2
Clinical Implications
Recognition Patterns
- Diagnosis is often delayed, sometimes into adulthood (average age 11 years), because early language development appears normal. 3
- Late diagnosis significantly impacts risk of depression and quality of life. 3
Genetic Considerations
- The phenotype is extremely heterogeneous with strong genetic contributions, though etiology involves both genetic and environmental factors. 1, 4
- Recurrence risk for siblings ranges from 4-7% for single affected children, increasing to 25-35% if two children are affected. 1
Common Pitfalls
Clinicians should not assume that normal early language development rules out autism spectrum disorder—the absence of language delay was the hallmark of what was formerly called Asperger's syndrome. 1 Approximately 90% of individuals with ASD have at least one co-occurring condition including depression, anxiety, ADHD, or sleep difficulties that require screening and management. 2