102b - Intellecutal Disability

Question 1

What is the most common cause of mild intellectual disability?

Answer 1

Familial Intellectual Disabilty

Usually IQ > 50

(Often, people with mild intellectual disability have family members with mild ID; Intelligence is highly heritable)

Question 2

The majority of people with Intellectual Disability have an IQ of [range]

Answer 2

The majority of people with Intellectual Disability have an IQ of 50-70

This is considered “mild” intellectual disability

Can receive an education, may live independently

Question 3

What is the difference between deterioration and degeneration?

What does this tell us about the cause of intellectual disability?

Answer 3

• Deterioration
  
  • Period of normal development, followed by an obvious injury and loss of neurologic function
  • Cause = the injury
• Degeneration
  
  • Period of normal development, followed by a gradual and progressive loss of function without obvious injury
  • Cause = likely metabolic disorder or progressive neurologic disease

Question 4

What is the most common inherited (genetic) cause of intellectual disability?

Answer 4

Fragile X syndrome

Question 5

What is the mean and standard deviation for IQ?

Answer 5

Mean = 100

Standard deviation = 15

Question 6

At which stage of development does intellectual disability most often begin?

Answer 6

Prenatal development

Includes the following etiologies:

• Chromosomal (Down Syndrome)
• Single gene (Fragile X)
• Malformation syndromes
  
  • Neural tube, hydrocephalus, microcephaly, anencephaly

Question 7

List 3 causes of intellectual disability with postnatal origin

Answer 7

• Hypoxic birth injury
• Brain injury
• Metabolic disorders
  
  • Technically the mutation is there prenatally, but no pathologic changes have occured until the postnatal period

Question 8

Give an example of a cause of intellectual disability with perinatal origin

Answer 8

Infectious disease

Question 9

IQ < __ defines intellectual disability

Answer 9

IQ < 70 defines intellectual disability

Standard Deviation = 15

<70 is more than 2 standard deviations below the mean

Question 10

What is the most common chromosomal cause of intellectual disability?

Answer 10

Down Syndrome