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MENTAL RETARDATION
DR SEDDIGH
HISTORY


Mental retardation recognized perhaps
longer than any other currently studied in
psychology
Written documents from ancient Egypt
made oblique reference to the condition as
early as about 1500 BC
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was often viewed as part of mental illness
relatively common
Historical Treatment of MR
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Egypt 1500 B.C.
Ancient Greece
200 A.D. Rome
Middle Ages
Reformation
Mental Retardation
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defined in the Diagnostic and Statistical
Manual of Mental Disorders-IV as:
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significantly subaverage intellectual functioning:
an IQ of approximately 70 or below
concurrent deficits or impairments in present
adaptive functioning in at least two of the following
areas:communication, self-care, home living,
social/interpersonal skills, use of community
resources, self-direction, functional academic
skills, work, leisure, health, and safety; and
onset before age 18 years.
Mental Retardation

defined in the Diagnostic and Statistical
Manual of Mental Disorders-IV as:
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
significantly subaverage intellectual functioning:
an IQ of approximately 70 or below
concurrent deficits or impairments in present
adaptive functioning in at least two of the following
areas:communication, self-care, home living,
social/interpersonal skills, use of community
resources, self-direction, functional academic
skills, work, leisure, health, and safety; and
onset before age 18 years.
Features of Mental Retardation
DSM-IV Criteria
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significantly subaverage IQ (<70)
concurrent deficits or impairments in adaptive
functioning
characteristics evident prior to age 18
Describing and Classifying
Mental Retardation
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5 DSM-IV-TR severity classifications for
mental retardation
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Mild – IQ of 50-55 to about 70 (Educable)
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Moderate – IQ of 35-40 to 50-55 (Trainable)
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Severe – IQ of 20-25 to 35-40 (Custodial)
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Profound – IQ below 20 or 25 (Custodial)
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Unspecified – presumption of mental
retardation but intelligence not testable with
standardized instruments
Mild Retardation
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Some 85% of all people with mental retardation
fall into the category of mild retardation (IQ 50–
70)
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They are sometimes called “educably retarded”
because they can benefit from schooling
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typically not identified until elementary school years
People with mild retardation typically need
assistance but can work in unskilled or
semiskilled jobs
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Intellectual performance seems to improve with age
Mild Retardation
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Research has linked mild mental
retardation mainly to sociocultural and
psychological causes, particularly:
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Poor and unstimulating environments
Inadequate parent-child interactions
Insufficient early learning experiences
Mild Retardation
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Although these factors seem to be the
leading causes of mild mental retardation,
at least some biological factors may also be
operating
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Studies have linked mothers’ moderate
drinking, drug use, or malnutrition during
pregnancy to cases of mild retardation
Moderate, Severe, and
Profound Retardation
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Approximately 10% of persons with mental
retardation function at a level of moderate
retardation (IQ 35–49)
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They can care for themselves and benefit
from vocational training
About 4% of persons with mental
retardation display severe retardation (IQ
20–34)
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They usually require careful supervision and
can perform only basic work tasks
Moderate, Severe, and
Profound Retardation
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About 1% of persons with mental
retardation fall into the category of
profound retardation (IQ below 20)
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With training they may learn or improve
basic skills but they need a very structured
environment
Severe and profound levels of mental
retardation often appear as part of larger
syndromes that include severe physical
handicaps
Prevalence
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1-3% of population (depending on cutoff)
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Slightly more males than females
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More prevalent in lower SES and in
minority groups, especially for mild MR;
no differences for more severe levels
Developmental Course
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Often children with mental retardation experience
helplessness and frustration in their learning
environments, which leads to low expectations and
limited success
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With appropriate training and opportunities, children who
have mild mental retardation may develop good adaptive
skills in other domains
Language and Social
Development
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Expressive language development may be weak in children with
Down syndrome
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Fewer signals of distress or desire for proximity with primary
caregiver, which can influence attachment
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Self-recognition often delayed, but positive
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Problems in the development of self-other understanding
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Deficits in social skills and social-cognitive ability; can lead to
rejection by peers
Emotional and Behavioral
Problems
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Emotional and behavioral disturbances four times greater than the
general population
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Impulse control problems, anxiety problems, and mood problems
common
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ADHD-related symptoms also common
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Pica and self-injurious behavior also common among those with
severe and profound MR
Other Disabilities Associated
with MR
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Can be associated with other pervasive
physical and developmental disabilities,
including sensory impairments, cerebral
palsy, and epilepsy
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Chance of other disability increases as
degree of intellectual impairment increases
Other Disabilities Associated
with MR (cont.)
Etiology
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The causes of mental retardation are many
and varied
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In some cases, pathology of a
physiological or biological nature can be
identified
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for as many as 30–40% of those with
mental retardation, causation is unknown
Causes of MR
• Genetic Causes (65%) Chromosomal
defects; Structural anomalies;Inborn errors of
metabolism
• Intrauterine Risk Factors (15%)
Asphyxia; Developmental defects; Malnutrition/
Intrauterine growth retardation Maternal
infections or diseases; Maternal substance
abuse
• Perinatal Risk Factors (10%):Anoxia;
Birth trauma;Low birth weight;Prematurity
• Neonatal and Postnatal Causes
(10%):Childhood infections and diseases;
Environmental toxins; Severe malnutrition,
Trauma
Causes of Mental Retardation
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Many organic causes have been discovered but majority
of cases cannot be explained, especially for mild mental
retardation
The two-group approach:
 organic mental retardation- includes chromosome
abnormalities, single gene conditions, and
neurobiological influences
 cultural-familial mental retardation- includes family
history of mental retardation, economic deprivation,
inadequate child care, poor nutrition, and parental
psychopathology
Causes of Mental Retardation
(cont.)
Inheritance and the Role of the Environment
 heritability of intelligence is approximately 50%
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prenatal influences may be mistaken for genetic
when they are actually environmental
Causes of Mental Retardation
(cont.)
Causes of Mental Retardation
Genetic and Constitutional Factors
 chromosomal abnormalities are the most common cause of
severe MR
 Down syndrome due to an additional 21st chromosome
 Fragile-X syndrome, the most common cause of inherited MR,
is associated with the FMR-1 gene
 Prader-Willi and Angelman syndromes both associated with
abnormality of chromosome 15; believed to be spontaneous
genetic birth defects occurring around the time of conception
 inborn errors of metabolism (referred to as single-gene
conditions) can result in syndromes such as PKU
Causes of Mental Retardation
(cont.)
Neurobiological influences
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adverse biological conditions (e.g., malnutrition, exposure to
toxins, Rubella, prenatal and perinatal stressors)
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infections, traumas, and accidental poisonings during infancy
and childhood
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prenatal alcohol exposure can lead to a Fetal Alcohol Spectrum
Disorder (FASD)
Social and Psychological influences
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deprivation of physical and emotional care and social
stimulation particularly influential
Genetic Factors
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Down syndrome
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three types of Down syndrome, each
resulting from a different type of
chromosomal error.
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Nondisjunction
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Translocation
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Mosaicism
Mental Retardation: Trisomy 21
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Distinctive facial features
Mild MR
Parental age
Medical complications
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Mental
Retardation:
Fragile
X
Physical characteristics
Females vs. Males
Autism
Genetic Factors
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phenylketonuria (PKU), an inherited metabolic
disorder that occurs in about 1 of every 10,000
live births
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Affected infants lack the ability to process
phenylalanine, severely damages the central
nervous system
Mental Retardation: PKU (genetic)
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Phenylalanine metabolizing deficiency
MR
Restricted diet
Genetic Factors
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Maple syrup urine disease
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Affected infants tend to excrete urine that has a
distinctive odor of maple syrup
may cause severe intellectual impairment,
although more often than not the condition is fatal
cause of this condition has been linked to
metabolic deficiencies of three separate amino
acids causing extreme CNS damage in the
newborn
Untreated maple syrup urine disease is fatal;
few untreated infants survive more than a few
weeks
Genetic Factors
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Galactosemia involves difficulty in
carbohydrate (sugar) metabolism, rather
than amino acid metabolism
Infants with galactosemia are unable to
properly process certain sugar
components in milk
Results are toxic damage to the infant’s
liver, brain, and other tissues
Treatment of children with
mental retardation
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Three types of prenatal intervention
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Chromosomal analysis for Down
Syndrome or other genetic abnormalities
may result decision to abort fetus
Treatment for Rh blood incompatibility
between mother and fetus may prevent
fetal damage.
Prenatal identification of a PKU problem
may result in maternal dietary restrictions
Prevention, Education, Treatment
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Child’s overall adjustment is a function of parental
participation, family resources, social supports, level of
intellectual deficit, temperament, and other specific
deficits
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Treatment involves a multi-component, integrated
strategy that considers children’s needs within the context
of their individual development, family and institutional
setting, and community
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Prenatal education and screening may prevent some cases
of MR
Prevention, Education, Treatment
(cont.)
Risk and protective factors affecting the psychological adjustment of intellectually
disabled children
Prevention, Education, Treatment
(cont.)
Psychosocial treatments
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intensive, child-focused, early intervention efforts are very
promising (particularly for disadvantaged children)
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optimal timing for intervention is in the preschool years
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behavioral techniques include shaping, modeling, graduated
guidance, and social skills training
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cognitive-behavioral techniques, such as self-instructional
training and metacognitive training
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family oriented interventions help families cope with the
demands of raising a child with MR
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Postnatal Interventions
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Infant stimulation programs provide positive
developmental environment for very young
children who are at risk because of prenatal or
later environmental circumstances
Specific instruction for young children in
language skills appears promising and probably
should be implemented as early as possible
Inclusion of young children of school age in
classrooms with non disabled peers
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Continuous name shift
“Mental Retardation” and “Learning
Disabilities” are outdated and unacceptable
for users
“Intellectual Disabilities” adopted by
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IASSID / AAMR
US President´s Commission
DSM-IVTR 2005
WITH
THANKS
DR SEDDIGH