Intellectual Disability Defined

WHAT IS IT?

Intellectual Disability (formerly known as mental retardation)

  • Official definition
    • Characterized by significant limitations both in intellectual functioning (IQ <70-75) and in adaptive behavior, which covers many everyday social and practical skills; originates before age 22 (American Association on Intellectual and Developmental Disabilities [AAIDD])
    • It is no longer defined by IQ alone, rather IQ is only part of the evaluation

CAUSE:

Intellectual disability can have many and varied etiologies, including

  • Acquired
    • Examples: Infection or injury
  • Genetic
    • Chromosomal
      • Examples:  Down syndrome or microdeletion syndrome
    • Molecular / Single Gene Disorder
      • Example: Fragile X syndrome

KEY POINTS:

Practical Definitions

  • Normal Intelligence
    • As an adult, able to reason, solve problems, think abstractly, comprehend complex ideas, and learn from experience
    • IQ >85
  • Learning, not intellectual, disability
    • As an adult, able to learn/understand complex information, but may require nontraditional teaching approaches
    • Normal IQ
  • Borderline intellectual disability
    • As an adult, able to learn/understand simplified information and probably able to live independently
    • Low normal IQ 75-85
  • Mild intellectual disability
    • As an adult, able to participate in most family activities and perform many independent tasks, but likely to need supervision similar to a middle school individual
    • Communication, conversation, and language are more concrete and immature than expected
    • IQ 50-75
  • Moderate intellectual disability
    • As an adult, able to participate in most family activities but likely to need supervision similar to a grade school person
    • Marked differences in conceptual skills
    • IQ 35-55
  • Severe intellectual disability
    • As an adult, attainment of conceptual skills is limited
    • Skills are similar to a toddler/preschool person (< 5-6 year old) requiring care and supervision accordingly
    • IQ 20-40
  • Profound intellectual disability
    • As an adult, very limited understanding of symbolic communication in speech or gesture
    • Skills are similar to an infant/toddler requiring care and supervision accordingly; dependent on others for all aspects of daily physical care, health, and safety
    • IQ < 20 or 25

Learn More – Primary Sources:

American Association on Intellectual Disabilities

Pediatrics: Comprehensive Evaluation of the Child With Intellectual Disability or Global Developmental Delays