Intellectual disability classification

ID Diagnosis - Brains & Behavior

• Core Criteria: Deficits in both intellectual & adaptive functioning, onset during developmental period.
• Intellectual Functioning: Assessed by IQ testing.
  • Mild: 50-70
  • Moderate: 35-49
  • Severe: 20-34
  • Profound: <20
• Adaptive Functioning: Failure to meet sociocultural standards for independence. 3 domains:
  • Conceptual (e.g., language, memory)
  • Social (e.g., empathy, social judgment)
  • Practical (e.g., personal care, job skills)

⭐ Etiology: Fetal alcohol syndrome is the leading preventable cause of intellectual disability in the United States.

The Severity Spectrum - More Than a Number

• DSM-5 shifted the primary basis for severity classification from fixed IQ scores to adaptive functioning.

• Severity is determined by the level of support required across three key domains.

• 📌 "Can Sam Play?" recalls the domains: Conceptual, Social, Practical.

• Mild (IQ ~50-70)

  • • Conceptual: Academic skills up to approximately 6th-grade level. Abstract thinking is impaired.
  • • Social: Immature in social interactions; difficulty regulating emotion and behavior.
  • • Practical: Can achieve independence in personal care (ADLs); needs support with complex tasks like legal decisions or healthcare management.

• Moderate (IQ ~35-50)

  • • Conceptual: Skills develop slowly, remaining at an elementary level in adulthood.
  • • Social: Marked differences from peers in social behavior; requires significant support for relationships.
  • • Practical: Can manage personal needs with extensive teaching; requires considerable support for household tasks and employment.

• Severe (IQ ~20-35)

  • • Conceptual: Limited attainment of conceptual skills; little understanding of written language or concepts involving numbers.
  • • Social: Spoken language is limited to single words or phrases.
  • • Practical: Requires support for all ADLs, including meals, dressing, and bathing; constant supervision is essential.

• Profound (IQ <20)

  • • Conceptual: Generally involves the physical world rather than symbolic processes.
  • • Practical: Dependent on others for all aspects of daily physical care, health, and safety.

⭐ Mild intellectual disability is the most common form, accounting for approximately 85% of all cases. These individuals can often live independently with minimal support.

ID Origins - Roots & Roommates

• Etiologies (often multifactorial):
  • Prenatal (~35%): Genetic syndromes (e.g., Down, Fragile X), inborn errors of metabolism, maternal infections (📌 TORCH), toxins (Fetal Alcohol Syndrome).
  • Perinatal (~10%): Hypoxic-ischemic encephalopathy, extreme prematurity, birth trauma.
  • Postnatal (~20%): Traumatic brain injury, meningitis/encephalitis, severe malnutrition, lead poisoning.
• Common Comorbidities ("Roommates"):
  • ADHD, Autism Spectrum Disorder (ASD), Cerebral Palsy, Epilepsy.

⭐ Fragile X Syndrome is the most common inherited cause of intellectual disability.

High-Yield Points - ⚡ Biggest Takeaways

• Intellectual disability requires deficits in both intellectual and adaptive functioning with onset during the developmental period.
• Adaptive functioning has three domains: conceptual, social, and practical.
• Severity (mild, moderate, severe, profound) is determined by adaptive functioning, not just the IQ score.
• Mild ID (IQ ~50-70): Can achieve 6th-grade academic skills; capable of independent living with support.
• Moderate ID (IQ ~35-50): Can achieve 2nd-grade skills; requires supervised living arrangements.