Autism Spectrum Disorders

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

Etiology - Roots & Risks

• 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.

⭐ 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.