Intellectual Disability

Question 1

The majority of cases of ID result from…

Answer 1

Changes in early brain development - believed to be related to a disruption of neuronal proliferation, apoptosis, migration, synaptogenesis, and/or dendritic pruning.

Question 2

Most prevalent form of ID with a known genetic etiology.

Answer 2

Down syndrome

Question 3

Most common familial or inherited form of ID with a known genetic etiology

Answer 3

Fragile X syndrome

Question 4

The leading worldwide preventable cause of ID is…

Answer 4

iodine deficiency causing thyroid hormone deficiency during pregnancy.

Question 5

Common environmental and preventable cause of ID is…

Answer 5

Fetal alcohol syndrome.

Question 6

Prevalence of ID with range of severity

Answer 6

85% mild (~ 6th grade level)
10% moderate (~2nd grade level)
3-4% severe
1-2 profound

Question 7

Life expectancy for individuals with Tay-Sachs disease is…

Answer 7

4 or 5 years

Question 8

Life expectancy for individuals with Down syndrome is…

Answer 8

60 years.

Question 9

Autism vs William’s syndrome cognitive profile

Answer 9

Autism: visual > verbal
William’s: verbal > visual

Question 10

The leading preventable cause of ID in the U.S. is…

Answer 10

Fetal alchohol syndrome

Question 11

How many known genetic causes of ID?

Answer 11

> 1,000

Question 12

Maple syrup urine disease

Answer 12

Rare genetic disorder characterized by deficiency of particular enzymes to metabolize certain protein amino acids properly (a.k.a., inborn errors of metabolism)

The condition gets its name from the characteristic sweet odor of affected infants’ urine, which resembles maple syrup.

Question 13

All states are mandated to screen for which two preventable causes of ID at birth?

Answer 13

phenylketonuria (PKU) and congenital hypothyroidism

Question 14

Intellectual Disability

Answer 14

1. IQ score ~2 SD below the mean (65-75)
2. Deficits in adaptive functioning relative to expectations for chronological age and sociocultural background.
3. onset occurs during developmental periods (childhood or adolescence)
4. Severity based on adaptive functioning, NOT IQ.

Question 15

Neuropathology of ID

Answer 15

1. Reduced cerebral volume
2. microcephaly with differential volume reductions (e.g., FAS)
3. enlarged head circumference (e.g., ASD) w/ mild ventricular enlargements

Question 16

What is the male to female ratio of ID?

Answer 16

1.5 to 1

Question 17

What are some GENETIC causes of ID?

Answer 17

Down syndrome
Fragile X syndrome
Williams Syndrome
Tay-Sachs disease
Maple syrup urine disease
Prader Willi Syndrome
Angelman Syndrome
Klinefelter syndrom
Tuberous Sclerosis

Question 18

What are some ACQUIRED causes of ID?

Answer 18

prematurity/low birth weight
exposure to alcohol and other drugs
environmental toxins
TBI
infections
iodine deficiency
stroke
epilepsy
meningitis
whooping cough
anoxia

Question 19

What are the first indicators of ID?

Answer 19

Failure to meet developmental milestones and/or physical characteristics associated with certain conditions (e.g., facial features in Down syndrome, growth deficiency and/or craniofacial abnormalities in fetal alcohol syndrome)

Walking in ~ 12 months
Speech in ~ 12 months

Question 20

What are prevention efforts to reduce incidence of ID?

Answer 20

1. Education regarding proper nutrition and eliminating alcohol and drug use during pregnancy
2. Childhood helmet utilization
3. Childhood vaccinations
4. Screening of medical and genetic conditions that are known to cause ID if not treated early (e.g., phenylketonuria, hypothyroidism)

Question 21

Mild ID

Answer 21

Approximately 85% of individuals with ID score in the mild range. Such individuals show delays in language but are usually fluent speakers in adolescence.

Acquire upto 6th grade level of ed.

They often require intermittent supervision and guidance.

Immature in social interactions
concrete language and problem solving

Question 22

Moderate ID

Answer 22

Approximately 10% of individuals with ID score in the moderate range. Such individuals normally attain functional language by adolescence

Acquire up to 2nd grade level.

require moderate levels of supervision

difficulty perceiving social cues, wiht limited social judgement and decision making skills.

Can care for basic personal needs with LOTS of teaching.

Question 23

Profound ID

Answer 23

Approximately 1–2% of individuals with ID score in the profound range. Such individuals may learn single words, acquire no academic skills, and require extensive supervision. They are dependent on others for physical care.

Question 24

Severe ID

Answer 24

Approximately 3–4% of individuals with ID score in the severe range. Such individuals display limited language, may demonstrate familiarity with the alphabet and simple counting, and require extensive supervision.

May understand very basic instructions or gestures, though they express themselves primarily through nonverbal or non-symbolic communication.

Question 25

Primary prevention in ID

Answer 25

improving nutritional status of women of child-bearing age (e.g., folic acid, iodine supplements)

Immunizations prior to pregnancy

avoid harmful exposure to chemical during pregnancy (e.g., alcohol, nicotine, illicit drugs)

Education regarding increased complications in pregnancy with advancing maternal age.

detection and care for high risk pregnancies

maternal screening and treatment (e.g., syphilis, Rh incompatibility)

Immunization of children, and genetic counseling.

Advances in prenatal screening and diagnosis also offer preventative options but carry ethical implications.

Question 26

Secondary prevention in ID

Answer 26

neonatal screening and appropriate medical treatment (e.g., phenylketonuria, galactosemia, hypothyroidism)

intensive early intervention services for children at risk for developing ID

Question 27

Tertiary prevention in ID

Answer 27

Tertiary prevention includes appropriate education, training, and support for families and caregivers.