is a Neurodevelopmental Disorders

(previously called Intellectual Disability, changed in DSM-V TR)


Is based on IQ? It was heavily based on IQ but now (as of 2024), needs “a score of two or more standard deviations below the population norm (approximately less than the 2nd/3rd percentile) on a standardized measure of adaptive skills such as the vineland adaptive behavior scales”^[]

Categories based on IQ levels

  1. mild (55-69)
  2. moderate (40-54)
  3. severe (25-39)
  4. profound (1-24)


Difficulty speaking delayed milestones socially impaired cognitively impaired temper tantrums aggressive behaviour struggle to remember difficulty in problem solving do not understand social cues difficulty expressing emotions can not take care of themselves - getting dressed, bath, etc

Mild intellectual disability: A majority of people with intellectual disability experience a mild to moderate form. They can learn practical life skills and function daily with minimal support. However, they might struggle to understand how things work and develop social skills.

Severe intellectual disability: experience significant developmental delays need more support than children with mild intellectual disabilities and have limited communication skills.

Profound intellectual disability: find difficulty in communication difficulty performing physical activities more likely to develop other medical conditions typically require round-the-clock care and support





Risk Factors

  1. Pathogens - drugs, lead, etc
  2. Illnesses or infections while in utero
  3. Head injuries
  4. Parental low IQ
  5. Low Oxygen levels during birth


Fragile X Down Syndrome Fetal Alcohol Spectrum Disorders Autism