intellectual disability

DSM-5 vs DSM-4 naming

now called intellectual disability change from previous "mental retardation". Change due to stigma; followed the guidelines of the American Association on Intellectual and Developmental Disabilities (AAIDD)

The AAIDD definition of intellectual disability?

o Intellectual disability is characterized by significant limitations both in intellectual functioning and in adaptive behavior as expressed in conceptual, social, and practical adaptive skills

o This disability begins before age 18 (distinguishing between developmental disability vs. deterioration

diagnostic criteria for intelectual disability?

3 main criteria: significant limitations in intellectual ability, significant limitations in adaptive functioning; onset before age 18

the current definition of intellectual ability is based on what?

IQ testing; BUT a child who scores low on an IQ test and functions well in his/her community is not a candidate for this diagnoses.

severity of intellectual disability is assessed in 3 domains:

Diagnostic Adaptive Behavior Scale (DABS):

1. Conceptual skills

2. social skills

3. practical skills

5 assumptions essential to the application of the AAIDD definition:

• Limitations in present functioning must be considered within the context of community environments typical of the individual's age, peers, and culture

• Valid assessment considers cultural and linguistic diversity as well as differences in communication, sensory, motor, and behavioral factors

• Within an individual, limitations often coexist with strengths

• An important purpose of describing limitations is to develop profile of needed supports

• With appropriate personalized supports over a sustained period, the life functioning of the person with intellectual disability generally will improve

DSM-5 changes to diagnostic criteria of intellectual disability?

→ There is explicit recognition that an IQ score must be considered within the cultural context of a person

→ Adaptive functioning must also be assessed and considered within the person's age and cultural group

→ No longer distinguish among mild, moderate, and severe intellectual disability based on IQ scores alone

Mild intellectual disability IQ range?

IQ of 50-55 to 70

moderate IQ range

IQ of 35-40 to 50-55

severe IQ range

IQ of 20-25 to 35-40

Profound IQ range

IQ below 20 or 25

mild intellectual disability prevalence?

85% of people w/ disability ail have mild. 15% will have moderate/severe/profound.

detail mild intellectual disability

o few physical impairments

o generally reach approximately the 6th grade level academically

o can develop vocational skills

o usually live in community

moderate intellectual disability prevalence?

10% of those w/ disability have moderate.

detail moderate intellectual disability

o often have obvious physical abnormalities

o academic achievement to 2nd grade level

o close supervision needed for both work and living situations

Severe intellectual disability prevalence?

3-4% of those w/ disability will have severe.

detail severe intellectual disability

• abnormal motor development

• communicative speech limited

• close supervision needed

profound intellectual disability prevalence?

1-2% of those w/ disability will have profound.

detail profound intellectual disability

• Motor skills, communication, self-care very limited

• Constant supervision needed

• Often institutionalized; tend to die prematurely

Models of intellectual disability?

Difference and developmental models

difference model

People with intellectual disability are qualitatively different from people with higher (normal) IQs due to their cognitive defect

developmental model

People with intellectual disability are not qualitatively different from those with higher (normal) IQs, but they develop more slowly and reach a lower ceiling of performance. People who are intellectually disabled are not qualitative different from their normal developing peers but they have a slower developmental trajectory.

causes of intellectual disability

• Genetic & Chromosomal factors

• Infection & Toxic Agents

• Prematurity or Other Trauma

• Ionizing Radiation

• Malnutrition

• Psychosocial Disadvantages

--> lead/mercury poisoning

gender differences

around 3/5 of those diagnosed are male.

neurological factors of down syndrome

• Chromosomal trisomy 21: an extra copy of chromosome 21

• 47 instead of 46 chromosomes

• can test for this (test is risky but risk is worth it)

neurological factors of fragile-x syndrome

mutation in the fMRI gene on the X chromosome. Second most common chromosomal cause of intellectual disability. Born with an X chromosome that has a genetic abnormality, leaving it prone to breakage and loss.

Recessive-gene disease

Phenylketonuria (PKU); PKU is a recessive-gene disease. The most common metabolic disorder to cause intellectual disability.

PKU

babies with PKU appear normal at birth but cannot break down the amino acid phenylalanine. The chemical builds up and is converted into substances that poison the system, causing severe intellectual dysfunction and several other symptoms. Recessive gene on Chromosome 12 (inherited as a genetically recessive trait)

Tay-Sachs disease

metabolic disorder resulting from a pairing of recessive genes. Children progressively lose their mental functioning, vision, and motor ability over the course of 2 to 4 years, and eventually die. 1 out of every 900 Jewish couples is at risk for having a child w/ this. Defect of lipid metabolism. Death almost certain by age 6.

maternal infections during pregnancy?

Cytomegalovirus, toxoplasmosis, rubella, herpes simplex, HIV and syphilis

turner's syndrome

• A single X chromosome and no Y chromosome

• Mental retardation is more common in this disorder than in the general population, although most are not significantly disabled

Klinefelter's syndrome

• Two X chromosomes and one Y chromosome

• Phenotypically male, small testes, occasionally mild mental disability

fetal alcohol syndrome

most have IQ's between 40-80. ~1-3 out of every 1,00 babies born in the US shows FAS

facial appearance of FAS

smooth ridge between nose and lip, thin edge around lip, small separation between upper and lower eyelids

growth problems of FAS

height, weight, or both at or below the 10th percentile

Central nervous system abnormalities

smaller head circumference and brain abnormalities visible on imaging. Neurological problems not due to injury or fever. Performance on functional measures substantially below that expected for an individual's age, schooling, or circumstances

maternal alcohol exposure

confirmed prenatal alcohol exposure; if this info is not available, children who meet all three of the above criteria would be referred for further testing.

infections agents

• infections & viruses during pregnancy, at birth, or in infancy to early childhood

o e.g. cytomegalovirus, toxoplasmosis, rubella, AIDS, syphilis, genital herpes, encephalitis

treatment of intellectual disability

residential treatment: small to medium sized community residences that teach self-sufficiency, devote more staff time to pt. care, and offer educational and medical services.

normalization

the principle that institutions and community residences should provide people with intellectual disability types of living conditions and opportunities that are similar to those enjoyed by the rest of society.

behavioral treatments of intellectual disability?

• Language, social, and motor skills training

• Method of successive approximation to teach basic self-care skills in severely intellectually disabled

o e.g., holding a spoon, toileting

• Applied behavioral analysis

other treatments for intellectual disability?

1. cognitive treatments: problem-solving strategies

2. computer-assisted instruction