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Mental Retardation


Characterized by 'significantly subaverage intellectual functioning' AND ' ... Heredity. Inborn errors of metabolism (e.g., Tay-Sachs) ... – PowerPoint PPT presentation

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Title: Mental Retardation

Mental Retardation
  • Psy 610A
  • Gary S. Katz, Ph.D.

Mental Retardation
  • Characterized by significantly subaverage
    intellectual functioning AND concurrent
    deficits or impairments in adaptive functioning.
  • Subaverage below 70 (Mean 100, SD 15)
  • VERY IMPORTANT low IQ is not sufficient
    evidence of mental retardation. Necessary, but
    not sufficient.
  • Onset before age 18.
  • Coded on Axis II

  • Measure of ones cognitive ability.
  • Usually consists of tests of verbal and nonverbal
  • SB-V
  • UNIT
  • TONI-3
  • Standard scores
  • Mean 100, SD 15
  • Score of 70 falls at roughly the 2nd percentile
  • Very rare IQs in Mental Retardation

Adaptive Functioning
  • How effectively individuals cope with common
    life demands and how well they meet the standards
    of personal independence expected of someone in
    their particular age group, sociocultural
    background, and community setting.
  • Typical measuring tool
  • Vineland Adaptive Behavior Scales II
  • Communication
  • Daily Living Skills
  • Socialization
  • Motor Skills (younger children)

Mild Mental Retardation (317)
  • IQ 50-55 to 70 (IQ of 50 .0429ile)
  • Largest group of MR patients (about 85)
  • Used to be referred to as educable
  • As a group, they often develop social,
    communication, and motor skills during the
    preschool years without concern.
  • At a later age, the MR becomes apparent.
  • In late teens, can acquire academic skills
    commensurate with a 6th grader.
  • As adults, can achieve social and vocational
    skills adequate for minimum self-support, but may
    need supervision, particularly when stressed.
  • Can usually learn to live independently or in
    supervised settings.

Moderate Mental Retardation (318.0)
  • IQ 35 to 55 (IQ of 35 .00073ile)
  • About 10 of the MR population
  • Used to be called trainable misnomer these
    folks can benefit from education. Avoid this
  • Most acquire communication skills during early
  • Can benefit from vocational training and with
    moderate supervision, attend to personal care.
  • Unlikely to progress beyond 2nd grade in academic
  • May learn to travel independently in familiar
  • Difficulties in social skills and recognizing
    social conventions can interfere with peer
    relationships in adolescence.
  • As adults, most can perform unskilled or
    semiskilled work under supervision.
  • Can live in the community, usually with

Severe Mental Retardation (318.1)
  • IQ 20-40 (IQ of 20 .0000048ile, 5 in
  • 3-4 of the MR population
  • During early childhood, acquire little or no
    communicative speech
  • During school-age period, may learn to talk and
    be taught elementary self-care skills.
  • Unlikely to progress beyond pre-academic skills
    (e.g., letter recognition, simple counting) but
    can master some survival sight words.
  • Most adapt well to life in the community in group
    homes or with their family members.

Profound Mental Retardation (318.2)
  • IQ below 25
  • About 1-2 of the MR population
  • Most of these individuals have an identifiable
    neurological condition that accounts for their MR
  • Considerable impairments in early childhood in
    sensorimotor functioning.
  • Optimal development may occur in
    highly-structured environments.
  • Motor development, self-care, and communication
    skills may improve if appropriate training is

Mental Retardation, Severity Unspecified
  • Used when there is a strong presumption of MR,
    but no scores to support the diagnosis.
  • VERY young children are hard to test young
    children with low IQs are even harder.
  • Difficulty could be to level of impairment or
    cooperation with testing procedures.

Associated Features and Disorders
  • No specific personality and behavioral features
  • Some are passive, others impulsive
  • Communication problems can lead to behavior
    problems, particularly in young children
  • Individuals with MR are vulnerable to
    exploitation by others
  • Rates of comorbid mental disorders in individuals
    with MR is 3-4 times greater than in the general
  • Common comorbidities ADHD, Mood Disorders, PDD,
    Stereotypic Movement Disorders
  • MR due to Down syndrome at a higher risk for
    Dementia of the Alzheimers Type.

Predisposing Factors
  • 30-40, no clear etiology is present.
  • More likely to have a specific etiology with
    Severe or Profound Mental Retardation
  • Heredity
  • Inborn errors of metabolism (e.g., Tay-Sachs)
  • Chromosomal abnormalities (Down Syndrome
    Trisomy 21)
  • Early alterations of embryonic development
  • Maternal alcohol consumption

Predisposing Factors
  • Environmental influences
  • Severe deprivation (nurturance, social
  • Mental disorders
  • Autistic Disorder, other PDD
  • Pregnancy and perinatal problems
  • Hypoxia, fetal malnutrition
  • General medical conditions acquired in infancy or
  • Lead poisoning, traumas, infections

Other Findings
  • No clear laboratory findings or physical exam
    findings in most cases.
  • Severe to profound MR often is accompanied by
    other lab/physical findings
  • Phenylketonuria
  • Seizures
  • Neuromuscular malformations

Culture, Age, Gender Features
  • Care should be taken to ensure that testing
    procedures reflect the ethnic, cultural, and
    linguistic background.
  • This is sometimes difficult to accomplish.
  • Some factors are linked to SES
  • Lead poisoning in low SES cultures
  • When no biological factors are present, MR
    severity is usually mild.
  • MR more common among males, 1.51 MF ratio.

Course Differential Diagnosis
  • Onset must be before 18yrs of age
  • Milder forms noticed later
  • Milder forms can, with appropriate training,
    develop good adaptive skills to no longer warrant
    the diagnosis as an adult.
  • No exclusion criteria make the diagnosis
    whenever the clinical findings indicate
  • Rule-outs
  • Learning Disorders (adequate IQ)
  • Communication Disorders (impairment limited to
    expressive/receptive skills)
  • Dementia (onset after a period of normal

Borderline Intellectual Functioning (V62.89)
  • IQ 71 to 84
  • NO impairment in adaptive skills
  • Coded on Axis II
  • Note IQ in the 71 to 84 range with accompanied
    adaptive skill deficits may be coded as Mild
    Mental Retardation

Case Material
  • Patient Stephanie
  • 10yrs old, 5th grade
  • History of special education support in her prior
    school settings
  • Referred to clinic because current school setting
    not providing adequate instructional support for

Case Material
  • Adopted in infancy from former Soviet republic
  • Adoption records indicated that biological mother
    was mildly mentally retarded and experienced
    hyperemesis (severe vomiting) during pregnancy.
  • Early infancy placed in an orphanage noted to
    have below average gross and fine motor skills.
  • At time of adoption, Stephanie was nearly a year
    old and unable to sit, crawl, or turn over.

Case Material
  • After adoption, Stephanie was provided with
    considerable early education support.
  • Developmental milestones reached late (walking at
    18mos, 1st words at 24mos)
  • Prior testing
  • 2007 WISC-IV IQ
  • FSIQ 54, VCI 57, PRI 53, WMI 56, PSI 88
  • Socially manipulated by older peers at older
    school no abuse reported.
  • Throughout elementary school, struggled with
    reading and expressive writing.

Case Material
  • Current assessment
  • Invited psychologist to her birthday party at
    first meeting.
  • Some expressive speech problems noted (wabbit
    and seep over)

Case Material
Case Material
Diagnostic Considerations?
Diagnostic Considerations