© cengage learning 2016 eric j. mash david a. wolfe intellectual disability (intellectual...
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© Cengage Learning 2016 © Cengage Learning 2016
Eric J. MashDavid A. Wolfe
Intellectual Disability (IntellectualDevelopmental Disorder)
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• Prior to mid-19th century: children and adults with intellectual disabilities were ignored or feared even by the medical profession
• Intellectual disability: a significant limitation in intellectual functioning and adaptive behavior which begins before age 18
Intelligence and Intellectual Disability (ID)
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• In the mid-19th century: Samuel G. Howe opened the first humanitarian institution in North America
• By the 1940s: parents increased humane care for their children
Intelligence and Intellectual Disability (cont’d.)
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• 1950: National Association for Retarded Children was formed
• 1962: President John F. Kennedy formed the President’s Panel on Mental Retardation
Intelligence and Intellectual Disability (cont’d.)
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• Evolutionary degeneracy theory– Pervasive in 19th century
– Intellectual and social problems of children with mental retardation were viewed as regression to an earlier period in human evolution
– J. Langdon H. Down interpreted “strange anomalies” as throwbacks to the Mongol race
The Eugenics Scare
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• Eugenics: “the science dealing with all influences that improve the inborn qualities of a race” ~ Sir Francis Galton– Led to the view that individuals with ID (moral
imbeciles, or morons) were threats to society
The Eugenics Scare (cont’d.)
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• Alfred Binet and Theophile Simon (1900s)– Commissioned by the French government to
identify schoolchildren who might need special help in school
– Developed the first intelligence tests• Measure judgment and reasoning of school
children (Stanford-Binet scale)
Defining and Measuring Children’s Intelligence and Adaptive Behavior
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• General intellectual functioning is now defined by an intelligence quotient (IQ or equivalent)
• ID is no longer defined on the basis of IQ– Level of adaptive functioning is also important
• Adaptive functioning: how effectively individuals cope with ordinary life demands and how capable they are of living independently
Defining and Measuring Children’s Intelligence and Adaptive Behavior (cont’d.)
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Specific Examples of Adaptive Behavior Skills
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• IQ is relatively stable over time– Except when measured in young, normally-
developing infants
• Mental ability is always modified by experience
• The Flynn Effect: the phenomenon that IQ scores have risen about three points per decade
• Are IQ tests biased or unfair?
The Controversial IQ
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• Clinical description - considerable range of abilities and interpersonal qualities– DSM-5 diagnostic criteria
• Deficits in intellectual functioning
• Concurrent deficits or impairments in adaptive functioning
• Below-average intellectual and adaptive abilities must be evident prior to age 18
Features of Intellectual Disabilities
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Diagnostic Criteria for Intellectual Disability
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• About 85% of persons with ID
• Typically not identified until early elementary years
• Overrepresentation of minority group members
• Develop social and communication skills
• Live successfully in the community as adults with appropriate supports
Severity Level: Mild
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• About 10% of persons with ID
• Usually identified during preschool years
• Applies to many people with Down syndrome
• Benefit from vocational training
• Can perform supervised unskilled or semiskilled work in adulthood
Severity Level: Moderate
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• About 3%-4% of persons with ID
• Often associated with organic causes
• Usually identified at a very young age– Delays in developmental milestones and
visible physical features are seen
• May have mobility or other health problems – Need special assistance throughout their lives
– Live in group homes or with their families
Severity Level: Severe
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• About 1%-2% of persons with ID
• Identified in infancy due to marked delays in development and biological anomalies
• Learn only the rudimentary communication skills
• Require intensive training for:– Eating, grooming, toileting, and dressing
behaviors
• Require lifelong care and assistance
Severity Level: Profound
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Examples of Support Areas
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• Approximately 1-3% of population (depending on cutoff)
• Twice as many males as females among those with mild cases
• More prevalent among children of lower SES and children from minority groups, especially for mild cases– More severe levels - identified almost equally
in different racial and economic groups
Prevalence
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Factors Accounting For Racial Differences
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• Developmental-versus-difference controversy– Do all children—regardless of intellectual
impairments—progress through the same developmental milestones in a similar sequence, but at different rates?
• Developmental position– Similar sequence hypothesis
– Similar structure hypothesis
Developmental Course and Adult Outcomes
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• Difference viewpoint: cognitive development of children with ID is qualitatively different in reasoning/problem-solving– Familial versus organically based ID
Developmental-Versus-Difference Controversy (cont’d.)
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• Many children with mild ID are able to learn and attend regular schools
• Often susceptible to feelings of helplessness and frustration in their learning environments
• Children who have mild ID are able to stay on task and develop goal-directed behavior – With stimulating environments and caregiver
support
Motivation
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• IQ scores can fluctuate in relation to the level of impairment
• Major cause of ID affects the degree to which IQ and adaptive abilities may change
• Slowing and stability hypothesis– IQ of children with Down syndrome may
plateau during middle childhood, then decrease over time
Changes in Abilities
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• Development follows a predictable and organized course
• Characteristics displayed with Down syndrome– The underlying symbolic abilities of children
are believed to be largely intact
– There is considerable delay in expressive language development; expressive language is weaker than receptive language
Language and Social Behavior
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• Fewer signals of distress or desire for proximity with primary caregiver
• Delayed, but positive, development of self-recognition
• Delayed and aberrant functioning in internal state language– Reflects emergent sense of self and others
• Deficits in social skills and social-cognitive ability; can lead to rejection by peers
Characteristics Displayed With Down Syndrome (cont'd.)
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• Rate is three to seven times greater than in typically developing children– Largely due to limited communication skills,
additional stressors, and neurological deficits
• Most common psychiatric diagnoses:– Impulse control disorders, anxiety disorders,
and mood disorders
• Internalizing problems and mood disorders in adolescence are common
Emotional and Behavioral Problems
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• ADHD-related symptoms are common
• Pica is seen in serious form among children and adults with ID
• Self-injurious behavior (SIB)– Can be life-threatening
– Affects about 8% of persons across all ages and levels of ID
Emotional and Behavioral Problems (cont'd.)
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• Health and development are affected
• Degree of intellectual impairment is a factor
• Prevalence of chronic health conditions in ID population is much higher than in the general population
• Life expectancy for individuals with Down syndrome is now approaching 60 years
Other Physical and Health Disabilities
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Chronic Health Conditions Among Children With Intellectual Disabilities
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• Scientists cannot account for the majority of cases, especially the milder forms
• Genetic or environmental causes are known for almost two-thirds of individuals with moderate to profound ID
Causes
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• Prenatal: genetic disorders and accidents in the womb
• Perinatal: prematurity and anoxia
• Postnatal: meningitis and head trauma
Prenatal, Perinatal, and Postnatal Causes
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• Organic group – there is a clear biological basis– Associated with severe and profound MR
• Cultural-familial group – there is no clear organic basis– Associated with mild MR
The Two-Group Approach
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• Four major categories of risk factors – Biomedical
– Social
– Behavioral
– Educational
Risk Factors
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CausesRisk Factors (cont'd.)
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• Genetic influences are potentially modifiable by environment
• Genotype: a collection of genes that pertain to intelligence
• Phenotype: the expression of the genotype in the environment (gene-environment interaction)
Inheritance and the Role of the Environment
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• Heritability describes the proportion of the variation of a trait attributable to genetic influences in the population– Ranges from 0% to 100%
– The heritability of intelligence is about 50%
• Major environmental variations affect cognitive performance and social adjustment in children from disadvantaged backgrounds
Inheritance and the Role of the Environment(cont'd.)
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• Chromosome abnormalities– Down syndrome is usually the result of failure
of the 21st pair of the mother’s chromosomes to separate during meiosis ► causes an additional chromosome
• Fragile-X syndrome is the most common cause of inherited ID
• Prader-Willi and Angelman syndromes– Both are associated with abnormality of
chromosome 15
Genetic and Constitutional Factors
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• Single-gene conditions: inborn errors of metabolism– Excesses or shortages of certain chemicals
which are necessary during developmental stages
– Cause of 3-7% of cases of severe ID
– Phenylketonuria results in lack of liver enzymes necessary to metabolize phenylalanine
• Can be treated successfully
Genetic and Constitutional Factors (cont’d.)
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• Adverse biological conditions– Examples: infections, traumas, and accidental
poisonings during infancy and childhood
• Fetal Alcohol Spectrum Disorder (FASD)– Estimated to occur in one-half to two per 1000
live births
• Teratogens increase risk of ID
Neurobiological Influences
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• Least understood and most diverse factors causing ID
• Environmental influences and other mental disorders account for 15-20% of ID – Deprived physical and emotional care and
stimulation of the infant
– Other mental disorders accompanied by ID, such as autism
• Parents are critically important
Social and Psychological Dimensions
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• Child’s overall adjustment is a function of:– Parental participation, family resources, social
supports, level of intellectual functioning, basic temperament, and other specific deficits
• Treatment involves a multi-component, integrated strategy– Considers children’s needs within the context
of their individual development, their family and institutional setting, and their community
Prevention, Education, and Treatment
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• ID related to fetal alcohol syndrome, lead poisoning, rubella) can be prevented if precautions are taken
• Prenatal programs for parents caution about use of alcohol, tobacco, drugs, and caffeine during pregnancy
Prenatal Education and Screening
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• Early intervention– One of the most promising methods for
enhancing the intellectual and social skills of young children with developmental disabilities
– Carolina Abecedarian Project provides enriched environments from early infancy through preschool years
– Optimal timing for intervention is during preschool years
Psychosocial Treatments
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• Initially seen as a means to control or redirect negative behaviors
• Association for Behavior Analysis (ABA) Task Force advocates that:– Each individual has the right to the least
restrictive effective treatment and the right to treatment that results in safe and meaningful behavior change
Behavioral Approaches
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• Self-instructional training and metacognitive training
• Verbal instructional techniques
• Teaching the child to be strategical and metastrategical
Cognitive-Behavioral Therapy
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• Help families cope with the demands of raising a child with ID
• Some ID children and adolescents benefit from residential care or out-of-home placement
• The inclusion movement integrates individuals with disabilities into regular classroom settings – Curriculum is adapted to individual needs
Family-Oriented Strategies