Autism Spectrum Disorders

Snapshot

• A 4-year-old boy presents to your office brought in by his parents.  They are concerned as he has no interest in interacting with his brother and demonstrates little to no interest in his mother or father.  The child knows only 10 words and his mother grows teary as she describes that he will not respond by hugging her when she tries to hug him.  The child spends most of his time stacking cans and organizing them by color in the kitchen pantry.

Introduction

• Overview
  • autism spectrum disorders (ASD) are neurodevelopmental disorders characterized by impairments in social communication and interaction
  • encompasses the following disorders (previously separate disorders until revised in the DSM-V)
    • autistic disorder
    • Asperger disorder
    • childhood disintegrative disorder
    • pervasive developmental disorder that is not otherwise specified
• Epidemiology
  • demographics
    • male:female ratio ~ 4:1 
    • usually diagnosed < 3 years of age
  • risk factors
    • family history of autism spectrum disorders
• Pathogenesis
  • remains unknown, but brain structure, connectivity, and functional abnormalities have been associated with autism spectrum disorders
• Associated conditions
  • intellectual disability and other developmental conditions (e.g., attention deficit hyperactivity disorder)
  • anxiety disorders
  • behavioral disorders
  • genetic syndromes (e.g., fragile X syndrome)
• Prognosis
  • difficult to determine in early childhood and depends on many factors
    • co-existing mental impairment
    • co-morbidities (i.e., chromosomal abnormalities)
• earlier intervention corresponds with better prognosis

Presentation

• Symptoms  
  • social communication and interaction deficits
    • increased attention towards inanimate objects and less attention towards people
    • lack of separation anxiety
  • restricted repetitive behaviors, interests, and activities
  • language impairment
  • majority have decreased IQ
    • minority have unusual talents (savants)
• Physical exam
  • DSM-V criteria for diagnosis of AS
    • social communication and social interaction deficit in many contexts such as
      • lack of social-emotional reciprocity
      • lack of nonverbal communicative behaviors
      • impairment in developing, maintaining, and understanding relationships
    • restricted and repetitive patterns of behavior, interests, or activities such as
      • motor movements that are stereotyped or repetitive (e.g., flipping objects)
      • inflexibility to change
      • restricted and fixated interests
        • typically with abnormal intensity or focus
      • hyper- or hyporeactivity or unusual interest in a sensory stimulus (e.g., fascination with lights)
    • symptoms must be present in the patient’s early developmental period in the absence of an organic etiology (e.g., hearing dysfunction) 
• symptoms cannot be better explained by other conditions (e.g., intellectual developmental disorder)

Differential

• Language disorder
  • key distinguishing factor
    • difficulty in communication stems primarily from comprehension and expression
    • restrictive repetitive behaviors are not present
• Rett syndrome
  • key distinguishing factor
    • exclusively in females
    • MECP2 gene mutation
• classic repetitive movements include mouthing, pill-rolling, and hand-twisting

Treatment

• Lifestyle
  • behavioral and educational intervention 
    • indication 
      • increase functional independence and quality of life
      • can improve communication and social skills
• Medical
  • second-generation antipsychotic agents (e.g. risperidone and aripiprazole)
    • indication
      • may alleviate repetitive behaviors