Autism Spectrum Disorders

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ASD Overview - Defining the Spectrum

  • Neurodevelopmental disorder.
  • Core features (DSM-5 criteria A & B):
    • Persistent deficits in social communication & interaction.
    • Restricted, repetitive patterns of behavior, interests, or activities (RRBs).
  • "Spectrum": wide variation in symptom presentation & severity levels (1, 2, 3).
  • Symptoms present in early developmental period.
  • Causes clinically significant functional impairment. ASD 2 main areas of impairment

⭐ ASD diagnosis requires BOTH social communication deficits AND at least two types of RRBs (Criterion B).

Etiology - Roots & Risks

Multifactorial Etiology of Autism Spectrum Disorder

  • Genetic Factors (Major Role):
    • High heritability: MZ twins ~70-90% vs DZ ~0-30%.
    • Polygenic: Many genes (e.g., SHANK3, NLGN).
    • Syndromic ASD: Fragile X, Rett, Tuberous Sclerosis, 15q duplication.
    • De novo mutations contribute.

    ⭐ Fragile X: most common monogenic cause.

  • Environmental Modifiers:
    • Prenatal: Advanced parental age (>35/40 yrs), valproate, maternal infections (rubella), diabetes.
    • Perinatal: Prematurity (<37 wks), low birth weight (<2500g), hypoxia.
  • Neurobiological Underpinnings:
    • Atypical brain growth (early overgrowth).
    • Altered neural connectivity.
    • Neurotransmitter (serotonin, GABA) & immune dysregulation.

Clinical Features - Signs & Symptoms

  • A. Social Communication & Interaction Deficits (All 3 required):
    • Social-emotional reciprocity (e.g., ↓ shared interests, ↓ conversation).
    • Nonverbal communication (e.g., ↓ eye contact, gestures, facial expressions).
    • Developing & maintaining relationships (e.g., ↓ imaginative play, peer interest).
  • B. Restricted, Repetitive Behaviors, Interests, Activities (RRBs) (≥2 of 4 required):
    • Stereotyped motor movements, object use, speech (e.g., echolalia, lining toys).
    • Insistence on sameness, routines, rituals (e.g., distress at changes).
    • Restricted, fixated interests (abnormal intensity/focus).
    • Sensory hyper/hyporeactivity or unusual sensory interests.
  • Early developmental onset.
  • Clinically significant impairment.
  • Not solely ID or GDD.

⭐ Language/social skill regression (often 18-24 mo.) is a key red flag.

Diagnosis - ASD Toolkit

  • Screening: M-CHAT-R/F for toddlers (16-30 months); ASQ, PEDS for general screening.
  • Diagnostic Evaluation:
    • Clinical assessment using DSM-5 criteria.
    • Gold Standard Tools: ADOS-2 (direct observation), ADI-R (parent interview).
  • Key Differentials: GDD, ID, ADHD, Language Disorders, Rett.

⭐ Early diagnosis (by 2-3 yrs) is crucial for timely intervention, improving outcomes.

Management - Helping Hands

  • Goal: Maximize functional independence & quality of life.
  • Multimodal Approach:
    • Behavioral Therapies:
      • Applied Behavior Analysis (ABA) is a cornerstone.
      • Speech, occupational, & social skills training.
    • Educational Interventions:
      • Individualized Education Programs (IEPs).
      • Structured teaching (e.g., TEACCH program).
    • Pharmacotherapy (for associated symptoms/co-morbidities):
      • Risperidone, Aripiprazole for severe irritability/aggression.
      • Stimulants for ADHD; SSRIs for anxiety/depression.
  • Parental Training & Support: Essential for skill generalization.
  • Early Intensive Behavioral Intervention (EIBI): Critical for best outcomes.

Autism Spectrum Disorder Management Plan

⭐ Risperidone and Aripiprazole are the only FDA-approved medications for treating irritability associated with Autism Spectrum Disorder in children and adolescents.

High‑Yield Points - ⚡ Biggest Takeaways

  • Core features: Deficits in social communication/interaction & restricted, repetitive behaviors (RRBs).
  • Symptoms must be present in early developmental period for diagnosis.
  • M-CHAT-R/F is a common screening tool for toddlers aged 16-30 months.
  • Strong genetic predisposition; high concordance in monozygotic twins (approx. 70-90%).
  • Frequently co-occurs with intellectual disability, ADHD, anxiety, and epilepsy.
  • Management focuses on early intensive behavioral intervention (EIBI) like ABA (Applied Behavior Analysis).
  • No causal link between vaccines and ASD has been scientifically established, a crucial point for counseling.

Practice Questions: Autism Spectrum Disorders

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Infantile autism is characterized by:

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Flashcards: Autism Spectrum Disorders

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Patients of autism spectrum disorder have higher incidence of abnormal fingerprints (_____)

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Patients of autism spectrum disorder have higher incidence of abnormal fingerprints (_____)

dermatoglyphics

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