*Intellectual Disability Statistics and Causes

Intellectual Disability Statistics

• Prevalence: 1-3% of the population.
    - Slightly higher prevalence observed in boys.

• Onset:
    - Onset occurs during the developmental period.
    - Exact age of onset depends on etiology and level of severity.
    - If intellectual disability (ID) is acquired, the onset may be abrupt, often occurring after certain illnesses, such as:
      - Meningitis
      - Encephalitis
      - Trauma

• Course:
    - Intellectual disability is generally lifelong.
    - Intervention can significantly improve intellectual functioning in many cases.
    - Certain individuals with ID may not meet the criteria in adulthood.

Intellectual Disability Causes

• Known Causes: 70% of cases.
    - Environmental Factors:
      - Prenatal: Exposure to diseases and drugs during pregnancy.
      - Perinatal: Difficulties during labor and delivery.
      - Postnatal: Factors such as deprivation, abuse/neglect, exposure to diseases/drugs, infections, and head injuries.

• Genetic Factors:
    - Mutation and Chromosomal Abnormalities:
      - Examples:
        - Rett Syndrome
        - Salem syndrome (potentially incorrect transcription of a known syndrome)
    - Inherited Conditions:
      - Fragile X syndrome
      - Down Syndrome, characterized by:
        - Flattened face, especially bridge of the nose.
        - Almond-shaped eyes that slant upward.
        - Short neck and small ears.
        - A tongue that tends to protrude from the mouth.
        - Caused by the presence of an extra chromosome 21 (trisomy 21).
        - Associated health issues include congenital heart problems and a high chance of developing dementia later in life.

• Unknown Causes: 30% of cases, which are not fully understood or identified yet.