MENTAL RETARDATION

What is mental retardation?

core features:

intellectual functioning

adaptive behaviour

begins early in life

levels of functioning:

mild MR 50-55 to 70

moderate MR 35-40 to 50-55

severe MR 20-25 to 35-40

profound MR below 25

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Intelligence

Definition and diagnosis:

AAMR 1992MR refers to substantial limitations in present

functioning. It is characterized by significantly subaverage intellectual functioning, existing concurently with related limitations in two or more of the following applicable adaptive skill areas:

communication self-care home living social skills community use self direction health and safety functional academics leasure Work manifests before 18

DSM-IV definition:

a. significantly subaverage intellectual functioning: an IQ of approximately 70 or below

b. concurrent deficits or impairment in present adaptive functioning in at least two of the following skill areas:

communication, self-care, home living,

social interpersonal skills, use of community resources, self-direction, functional academic skills, work, leisure, health, and safety

c. onset is before age 18 years

provides codes for mild, moderate, severe and profound MR

Developmental course

Stability of intelligence:

in normal children:

in children with MR:

at lower levels …stability

mild MR ….. fluctuations

 

Stability and type of retardation:

children with Downs Syndrome:

decrease in IQ  fragile x:

middle childhood or teen years

ages 10-15 

 

Stability of adaptive behaviour:

Downs: no gains between 7 and 11 years

fragile x slowing in early teen years

intervention programs 10-15 points gains in IQ

Prevalence:adaptive functioning consideredmild MR instablemild MR and schoolingdeath of low MR

overall 2% severe levels .4%

Epidemiology

Epidemiology

sex differences:

more males than females

social class:

Low SES

severe MR

ethnic minorities

 

Theoretical frameworksI. Developmental approaches

ZIGLER (1969)

“familial mental retardation”

similar sequence approach

similar structure approach

matched on MA

when familial supported

 

 

Theoretical frameworks

famial MR: deficits in

memory

information processing skills

??……..motivational factors

 but similar on Piagetian tasks

organic MR:

worse than MA matched

specific areas of deficit:

Downs linguistic grammar

Fragile x sequential processing

Williams Syndrome high language abilities

domains are modular

different MR different behavioural functioning

 

II. Families and Ecologies:

Stress and coping:

extra stressor

effects

Factors help to cope:

SES

two parent

women in better marriages 

II. Families and Ecologies:

Mothers

social-emotinal support

information about child

help in child care

Fathers

financial cost

childs temperament

relationship with the child

Double ABCX model: crises of raising the child X childs characteristics A family resources B family’s perception of the child C

mothers may have many reactions

 

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Etiology

Cause not known in 30-40% of clinic cases Cause harder to determine in mild cases Organic versus Cultural-familial (table 11-6) Organic (Table 11-7)

Prenatal Perinatal Postnatal

Genetic Syndromes Table 11-8 Down Syndrome

Most common single disorder

Caused by Trisomy 21 Higher risk with

maternal age Alzheimer’s Moderate to severe MR Delayed speech, verbal

short term memory and auditory processing deficits

Genetic Syndromes Fragile X

Most common inherited form

Fractured X chromosome More common in boys-

they have more severe forms

Long faces, prominent jaws, large ears (males)

Visual-spatial, sequential processing, motor coordination and executive function deficits

Social impairments

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Genetic Syndromes

Williams SyndromeRareDeletions on Chromosome 7Mild to moderate MRGeneral knowledge & visual spatial deficitsRelative strengths in language Elfin appearance

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Multifactor Causation

Current theories posit a complicated interaction between biology and environment (Table 11-9)

ETIOLOGIES

“two group approach” 

organic familial

social functionmarked imp. Minor to none

 cause majority organic minority org.

 family history normal low IQ

organic familial

background equal SES low SES

 

appearance dysmorphic normal

 

medical comp. Low fertility normal

physical hand.

Short life expect.

 

Psychiatric comp. Severe disord. similar dis.

Autism to normal but

Self injury more freq.

Hyperactivity

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Behavioral Problems and Co-occurring Diagnoses

These include: Depression Attention Problems and Hyperactivity Aggression Obsessive-compulsive behavior Schizophrenia Autism Stereotyped behavior Self Injurious Behavior