(Formerly referred to as “Mental Retardation” – now outdated and stigmatizing)
1. Definition
Intellectual Disability (ID) is a neurodevelopmental disorder characterized by:
- Significant limitations in:
- Intellectual functioning (IQ ≤ 70-75)
- Adaptive behaviors (daily life skills like communication, self-care)
- Onset before age 18
Key Terms:
- Global Developmental Delay (GDD): Used for children under 5 when IQ testing isn’t possible.
- DSM-5 Severity Levels: Mild, Moderate, Severe, Profound.
2. Causes of Intellectual Disability
Genetic Factors (30-50% of cases):
- Down Syndrome (Trisomy 21)
- Fragile X Syndrome
- Phenylketonuria (PKU)
Prenatal/Perinatal Causes:
- Fetal Alcohol Syndrome
- Maternal infections (Rubella, Zika)
- Premature birth complications
Environmental/Childhood Factors:
- Severe malnutrition
- Traumatic brain injury (TBI)
- Lead/mercury poisoning
3. Diagnosis Criteria
A. Intellectual Impairment
- IQ score ≤ 70-75 (measured by tests like Stanford-Binet or WISC)
- Note: IQ alone is insufficient – must include adaptive functioning deficits.
B. Adaptive Behavior Deficits
- Conceptual skills (language, math, memory)
- Social skills (empathy, friendships)
- Practical skills (dressing, hygiene, money management)
C. Onset in Developmental Period
4. Severity Levels (DSM-5)
| Level | IQ Range | Functional Abilities |
|---|---|---|
| Mild | 50-69 | Can learn practical skills, live independently with support |
| Moderate | 35-49 | Requires supervision for daily tasks |
| Severe | 20-34 | Limited speech, needs 24/7 care |
| Profound | <20 | Total dependence on caregivers |
5. Management & Support Strategies
A. Early Intervention (0-3 years)
- Speech therapy
- Occupational therapy
- Special education programs
B. School-Age Support
- IEPs (Individualized Education Plans)
- Life skills training (cooking, hygiene)
C. Adult Living Options
- Supervised group homes
- Vocational training programs
- Community inclusion initiatives
D. Medical Treatments (Symptom-Based)
- Anticonvulsants (for comorbid epilepsy)
- Behavioral therapy for aggression/anxiety
6. Associated Conditions
- Autism Spectrum Disorder (ASD) (~30% comorbidity)
- Cerebral Palsy
- Hearing/Vision Impairments
- Mental Health Disorders (Anxiety, Depression)
7. Prognosis & Quality of Life
- Mild ID: Often marry, work with minimal support.
- Moderate-Severe ID: Require lifelong assistance but can achieve personal milestones.
- Key Factor: Early intervention dramatically improves outcomes.
8. Ethical & Social Considerations
- Avoid Outdated Terms: “Mental retardation” is offensive; use “intellectual disability” or “developmental disability.”
- Person-First Language:
✅ “A person with an intellectual disability”
❌ “An intellectually disabled person”