Transcript Intellectual Disability: Definition, Classification

SW 644: Issues in Developmental Disabilities
Intellectual Disability: Definition,
Classification and Assessment
Lecture Presenter:
Lara S. Head, Ph.D.
Post Doctorate Fellow in Psychology
Waisman Center
University of Wisconsin-Madison
Issue of Change: Providing Context
 Terminology
 Shift from ‘mental retardation’ to
‘intellectual disability’
 Definition
 Evolving
 Assessment
 Balance between intelligence and
adaptive behavior
 Implications
 Increasing consistency
Issue of Change - Terminology
 Historical conceptualizations
 Presence of individuals with intellectual
impairments in society has been well documented
over time (Example: Roman and Greek Culture)
 Early religious leaders were among first to
advocate for humane treatment
 Changing perceptions
 John Locke
 Jean-Marc-Gaspard Itard
 Edouard Seguin
Classification
 A classification system is introduced
 J. Langdon Hayden Down
 Classification by physical appearance
 Late 1800’s: Recognition of brain
pathology in intellectual disabilities
 Education reform and Residential Schools
 Theodore Simon and Alfred Binet
 Early 1900s
 Classification based on IQ
What is Intellectual Disability?
 Current Perspective
 A state of functioning rather than a
person-centered trait
 Limitations in intellectual functioning
 Difficulties in meeting the ordinary
challenges associated with daily life
 A social-ecological view
 Not an illness or a disease
 Medical model view
 Perception of ‘sick’
What is Intellectual Disability?
 Types of causes
 Genetic
 Chromosomal
 Prenatal influences
 Perinatal influences
 Postnatal influences
 Diagnosis of intellectual disability is a
process
 No single diagnostic test
 Defined by many organizations
Terminology Differences
 Many different terms to describe
intellectual disability
 Shift in terminology in last few years
 Mental Retardation / Intellectual
Disability
 Significant limitations in intellectual
functioning and in adaptive behavior
 Before 18
 Population of application remains the
same (www.aaidd.org)
Terminology Differences
 Developmental Disability
 A severe, chronic disability that begins any
time from birth through age 21 and is
expected to last a lifetime.
 May be cognitive, physical, or a combination
of both
 Serious limitations in everyday activities
(www.nacdd.org)
 Disability
 Personal limitations that represent a
substantial disadvantage with attempting to
function in society
 Can originate at any age (www.aapd.org)
Terminology Differences
 Benefits to terminology change
 Reflects the changed construct of disability
 Aligns better with current professional
practices
 Provides a logical basis for individualized
supports provision
 Less offensive to individuals with disability
 More consistent with international
terminology
Issue of Change- Definition
 Definition
 Evolving and dependent on assumptions
that clarify the context from which it is
derived and applied
 Significant consequences
 Service eligibility
 Subject or not subject to certain practices
 Exempted or not exempted
 Included or not included
 Entitled or not entitled
Development of Definition
 1961: AAMR introduces term “mental
retardation”
 1973: Introduction of standard
deviation to describe intellectual
disability as well as 18 as upper age
limit for initial manifestation of
intellectual disability
 1980s: Specific IQ values with ranges
2002 AAIDD System
 Diagnosis
 Essential to establishing eligibility
 Classification
 A means of communication
 Planning Supports
 Enhancing personal outcomes
 Four different definitions for intellectual
disability: focus on DSM IV and AAIDD
2002 AAIDD System
 Multidimensional Approach
 Other systems, like DSM IV, is multiaxial and focuses on medical
disorders and stressors
 Important to assess current
functioning and strengths of
individual
2002 AAIDD System
 Diagnosis
Core definition (2002)
 Mental retardation is a disability
characterized by significant limitations
in intellectual functioning and in
adaptive behavior
 Is expressed in conceptual, social,
and adaptive skills
 Originates before age 18
2002 AAIDD System
 5 essential assumptions
 Limitations must be considered within
context
 Diagnosis based on a valid assessment that
considers various factors
 Recognizes that limitations and strengths
coexist
 Limitations provide information to develop
support needs
 With personalized supports provided over
time, life functioning will improve
2002 AAIDD System: Intelligence
 General mental capacity includes:
 Reasoning
 Problem-solving
 Abstract thinking
 Comprehension
 Learning from experience
 Limitations influence other aspects of
functioning
 Best represented by intelligence test scores
using appropriate test instruments
2002 AAIDD System: Adaptive Behavior
 Collection of skills that individuals
learn to use in order to function in
everyday life
 Conceptual Skills
 Receptive and expressive language
 Reading and writing
 Money concepts
 Self-directions
2002 AAIDD System: Adaptive Behavior
 Social Skills
 Interpersonal skills
 Responsibility
 Self-esteem
 Practical Skills
 Eating
 Dressing/Bathing
 Mobility
 Daily Living tasks
2002 AAIDD System: Classification
 Classification
 Dimension I
 Intellectual Abilities
 Dimension II
 Adaptive Behavior
 Dimension III
 Participation, Interactions, and Social
Roles
 Dimension IV
 Health
 Dimension V
 Context
2002 AAIDD System: Supports
 Planning Supports
 Human development
 Teaching and education
 Home living
 Community living
 Employment
 Health and safety
 Behavioral
 Social
 Protection and advocacy
DSM IV – TR Definition
 Significantly below average intellectual
functioning: IQ of approximately 70 or below
on an individually administered IQ test
 Accompanied by significant limitations in
adaptive functioning in at least 2 skill areas:
 Communication, self-care, home living,
social/interpersonal skills, use of
community resources, self-direction,
functional academic skills, work leisure,
health, and safety (American Psychiatric
Association, 2000, p. 41)
 Onset before age 18
DSM IV-TR
Levels of Mental Retardation
 Mild MR
 55-70 IQ
 Adaptive limitations
 Moderate MR
 35-54 IQ
 Adaptive limitations
 Severe MR
 20-34 IQ
 Adaptive limitations
 Profound MR
 Below 20 IQ
 Adaptive limitations
in 2 or more domains
in 2 or more domains
in all domains
in all domains
Who are the Intellectually Disabled?
 Prevalence
 Less than 1% of the overall population
 Estimated 3% of the population in the
United States
 Residence
 WI
 Approximately 81% reside in a
home/supported living setting
 Approximately 19% reside in a state
public/private facility
(www.cu.edu/ColemanInstitute/stateofthe
states/Wisconsin.html)
Special Education Services – Fall 2005
State
Ages 3-21
Wisconsin
130,076
Minnesota
116,511
Illinois
323,444
Michigan
243,607
Indiana
177,826
Iowa
72,457
Site: www.ideadata.org
Special Education Services – Fall 2005
Disability Category
Age 5
Age 10
Specific Learning Disabilities
7,607
235,787
Speech/Language Impairments
164,082
115,780
Mental Retardation
11,688
36,678
Emotional Disturbance
3,373
30,579
Multiple Disabilities
4,171
9,753
Hearing Impairments
3,228
5,909
Orthopedic Impairments
3,407
5,313
Other Health Impairments
6,590
51,225
Visual Impairments
1,349
2,093
Autism
13,848
18,216
Deaf-blindness
86
112
Traumatic Brain Injury
504
1,729
Developmental Delay
82,261
0
All Disabilities
302,194
512,994
Site: www.ideadata.org
Who are the Intellectually Disabled?
 Age differences
 Increased prevalence typically from
preschool to middle childhood years
 Increased prevalence in teen years
 Decreased prevalence in older individuals
 Gender differences
 Increased reports in males
Who are the Intellectually Disabled?
 Associated impairments
 20-25% visually impaired
 10% hearing impaired
 Seizure disorders occur in
approximately 33% of individuals in
institutional settings
 Cerebral palsy occurs 30-60% of
individuals in individuals with severe
intellectual disability
Who are the Intellectually Disabled?
 Psychiatric disorders
 Estimates of 4-18% of individuals with
ID have a co-occurring psychiatric
disorder
 4.4% Schizophrenia
 2.2% Depressive disorder
 2.2% Generalized Anxiety Disorder
 4.4% Phobic disorder
Deb, Thomas, & Bright 2001
Profiles of Intellectual Disability
 Mild ID Profile
 Minor delays in the preschool period
 Evaluation often only after school entry
 2-3 word sentences used in early primary
grades
 Expressive language improvement with time
 Reading/math skills – 1st to 6th grade levels
 Social interests typically age appropriate
 Mental age range of 8-11 years of age
 Persistent low academic skill attainment can
limit vocational possibilities
Profiles of Intellectual Disability
 Moderate ID Profile
 More evident and consistent delays in
milestones
 At school entry may communicate with single
words and gestures
 Functional language is the goal
 School entry self-care skills – 2-3 year range
 By age 14: basic self-care skills, simple
conversations, and cooperative social
interactions
 Mental age of 6-8 years of age
 Vocational opportunities limited to unskilled
work with direct supervision and assistance
Profiles of Intellectual Disability
 Severe ID Profile
 Identification in infancy to two years
 Often co-occurring with biological anomalies
 Increased risk for motor disorders and epilepsy
 By age 12: may use 2-3 word phrases
 Mental age typically 4-6 years of age
 As adults assistance typically required for even
self-care activities
 Close supervision needed for all vocational tasks
Profiles of Intellectual Disability

Profound ID Profile
 Identification in infancy
 Marked delays and biological anomalies
 Preschool age range may function as a 1-yearold
 High rate of early mortality
 By age 10: some walk/acquire some self-care
skills with assistance
 Gesture communication
 Recognizes some familiar people
 Mental age range from birth to 4 years of age
 Functional skill acquisition not likely
Variations in ID Classification
 Childhood intervention history
 Educational experiences
 Socialization opportunities
 Adult habilitative and prevocational
activities
 Presence of physical impairment
Issue of Change - Assessment
 Assessment
 Establishing a balance between
the importance of IQ and
identifying functional behaviors
and support needs
 Increased recognition of the
cultural implications of
intelligence testing
Identifying Individuals with ID
 Assessment
 Cognitive/intellectual ability
 Adaptive behavior functioning
Cognitive Ability Assessment
 Standardized and Norm-referenced Tests
 Standardized: a test given in a certain,
prescribed way using the same set of
directions with every individual
 Norm-referenced: Examining an individual’s
test performance in comparison to the
average performance or “norm”, of other
individuals of the same chronological age
 Validity and Reliability
 Validity: Does the test measure what we
want?
 Reliability: Does the test measure
consistently?
Cognitive Ability Assessment
 Normal Curve / Distribution
 Represents the distribution of abilities in
the general population
 Demonstrates the extent to which
individuals deviate from the mean based
on a normal distribution of scores
 Average IQ = 100
 Range 85-115 = approximately 68%
 Fewer people are represented at the
extreme ends of the curve
 IQ < 70 = approximately 3%
Cognitive Ability Assessment
 Normal Curve
Cognitive Ability Assessment
 Types of Intelligence
 Verbal Ability
 Nonverbal Ability
 Other theoretical models
Cognitive Ability Assessment
 Common Measures
 WISC Series (WISC IV; WAIS II;
WPPSI, etc.)
 Stanford-Binet V
 Woodcock-Johnson Test of Cognitive
Abilities
 Bayley Scales of Infant Development
 Kaufman Assessment Battery for
Children
Cognitive Ability Assessment
 Stability over time
 For most, intelligence remains stable
after 5 years of age (Zigler, Balla, &
Hodapp, 1984)
 However, variability in individual
growth patterns warrant periodic
evaluation
Other Consideration in
Cognitive Ability Assessment
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How reliable and valid was the test
Other Important Features: culture, language barriers, physical impairments
Ability to accurately compare individual’s performance against a normative
group when presence of some physical issues
Need to be vigilant with these issues when conducting testing, review the
literature and talking to individuals and their families
Also consider if there was a great deal of scatter within the individual’s
performance?
Intellectual disability is a feature of many different conditions, many
different disorders
The diagnosis of intellectual disability should always be made whenever the
diagnostic criteria are met regardless of whether or not there are other
conditions that are present
Individuals with intellectual disability are vulnerable to lots of other
conditions simply by the nature of how they do function and the nature by
which their ability to execute their skills effectively can be compromised
Adaptive Behavior Assessment
 “The adaptive behavior approach
was originally intended to
encourage one to look at the
individuals with an eye toward
remediation and prescriptive
assessment, rather than merely
labeling and classifying.”
(Nihira, 1999, p. 8)
Adaptive Behavior Assessment
 Adaptive behavior can be difficult to
assess:
 Adaptive behavior is not
independent of intelligence
 Behaviors accepted as adaptive at
one age may not be acceptable at
another age
 What constitutes adaptive behavior
is variable
Adaptive Behavior Assessment
 Adaptive Behavior
Conceptual Skills:
communication, functional academics, selfdirection, money concepts
Social Skills:
interpersonal skills, self-esteem,
naiveté/gullibility, self-governance (obeys
rules)
Practical Skills:
self-care, domestic skills, work, health &
safety
Adaptive Behavior Assessment
 Relationship between IQ and adaptive
behavior functioning
 r = .30 -.50 (Harrison & Oakland, 2003)
 Highest correlation in the lower IQ
ranges
 More variability in adaptive behavior
scores in higher IQ ranges
 Adaptive behavior and intelligence work
together
Adaptive Behavior Assessment
 Current standards of practice
 Assess present functioning
 Assess typical functioning
 Consider the person’s age and culture
 Assessment using standardized measure of
AB normed on general population
 Compare person’s adaptive behavior to
community standards and expectations
 Use multiple informants
 Retrospective assessment (Schalock et al.,
2007)
Adaptive Behavior Assessment
 Measures
 Vineland II Adaptive Behavior Scales
(Sparrow, Cicchetti, & Balla, 2005)
 Birth to age 90
 Three versions
 Four Domains – Communication, Daily
Living Skills, Socialization, Motor Skills
 Maladaptive Behavior Domain
 Adaptive behavior composite score
 Survey scale norms based on 3,000+
people
Adaptive Behavior Assessment
 Measures
 AAMR Adaptive Behavior Scales (ABS)
 School/Community (Lambert, Nihira, & Leland,
1993)
 Residential/Community (Nihira, Leland, &
Lambert, 1993)
 Scales of Independent Behavior– Revised (SIB-R)
(Brunininks, Woodcock, Weatherman, & Hill,
1996)
 Adaptive Behavior Assessment System 2nd
Edition (ABAS – II) (Harrison & Oakland, 2003)
Why Change? - Implications
 Professional-Parent Communication
 Maximize the role of professional in shaping
parent perceptions
 Recognize the adaptation process as an
evolving experience for parents
 Need to listen to and value the perspectives
of parents
 Consider the unique needs of all family
members
 Need to be sensitive about dreams and
hopes of parents for their children
 Need to respect family’s coping style
Why Change?
 Service Provision
 Effective resource utilization
 Lifetime expenditure -- $51.2 billion
for
individuals with ID (www.cdc.org)
 Increased emphasis on adaptive
behavior functioning and habilitation
services
 Utilizing support needs assessment as a
tool towards improved interventions
Why Change?
 Legal Implications
 Identifying individuals at risk as
vulnerable adults
 Individuals within the criminal justice
system
 As victims – 4 to 10 times increased
risk (Sobsey, 1994)
 As suspects/offenders – 4-10% of the
prison population (Sullivan & Knutson,
2000)
Future Directions
 Research / discussion will continue
 Refining the construct of intellectual disability
 Understanding the influence of terminology
 Expanding our understanding of the nature of
intelligence, adaptive behavior and functional
differences
 Improving reliability of diagnosis
 Improving knowledge of human functioning
 Examining the relationships among groups
 Determining support provision
 Recognizing the role of advocacy
Resources - Websites

www.aaidd.org – American Association on Intellectual and
Developmental Disabilities (formerly AAMR)
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www.nacdd.org – National Association of Councils on
Developmental Disabilities
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www.familyvillage.wisc.edu – Family Village (University of
Wisconsin-Madison)
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www.fragilex.org – National Fragile X Foundation
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www.cureautismnow.org – Cure Autism Now
Resources - Websites

www.autism-society.org – Autism Society of America
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www.ndss.org – National Down Syndrome Society

www.mpssociety.org/content/4163/Tributes/ -- National MPS
Society (Hunter syndrome)

www.ideadata.org – Special Education Population Figures –
Federal/State
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www.cu.edu/ColemanInstitute/stateofthestates -- Disability
Population Figures – State

www.aapd.org – American Association of People with
Disabilities
Resources – Video/Images

www.fragilex.org/photogallery/photogallery.htm -- Fragile X
photographs

www.taaproject.com/media/the-taap-video/ -- Autism Acceptance
Project

www.taaproject.com/media/video-vault/the-reason-the-joy-of-adam/

www.cdlsusa.org/familyalbum/index.html -- Cornelia de Lange
Syndrome Images – CDLS Foundation
Resources – Video/Images

www.cdlsusa.org/video/index.shtml -- CDLS Video

www.ucp.org/ucp_generalsub.cfm/1/9/12171 -- United Cerebral Palsy
“One Life”

www.lndinfo.org/LNDPatients/Equipment.html -- Lesch-Nyhan Disease
Registry – Images

www.rettsyndrome.org/content.asp?contentid=444 – International
Rett Syndrome Association

www.youtube.com/watch?v=_TbWcdN-W8o – Living a Life of Disability
video
Resources – Further Reading
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American Psychiatric Association. (2000). Diagnostic and
statistical manual of mental disorders (4th ed., Text rev.).
Washington, DC: Author.
Deb, S., Thomas, M., & Bright, C. (2001). Mental disorder in
adults with intellectual disability: Prevalence of functional
psychiatric illness among a community-based population aged
between 16 and 64 years. Journal of Intellectual Disability
Research, 45 (6), 495-505.
Elks, M. A. (2005). Visual Indictment: A contextual analysis of
The Kallikak Family photographs. Mental Retardation, 43 (4), 268280.
Luckasson, R., Borthwick-Duffy, S., Buntinx, W. H. E., Coulter, D.
L., Snell, M. E., Spitalnik, D. M. Spreat, S., & Tasse´, M. J. (2002).
Mental Retardation: Definition, classification, and systems of
supports (10th ed.). Washington, DC: American Association on
Mental Retardation.
Resources – Further Reading
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Snell, M. E. & Vorrhees, M. D. (2006). On being labeled with
mental retardation. In H. N. Switzky & S. Greenspan (Eds.),
What is mental retardation: Ideas for an evolving disability
(pp. 61-80). Washington, DC: American Association on
Mental Retardation.
Sattler, J. & Hoge, R. D. (2006). Assessment of children:
Behavioral, social, and clinical foundations (5th ed.). Jerome M.
Sattler, Publisher, Inc.: San Diego, CA.
Schalock, R.L., Buntinx, W., Borthwick-Duffy, A., Luckasson,
R., Snell, M., Tasse´, M., & Wehmeyer, M. (2007). User’s
Guide: Mental retardation: Definition, classification, and
systems of supports (10th ed.). Washington, DC: American
Association on Intellectual and Developmental Disabilities.
Resources – Further Reading
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Schalock, R. L. et al. (2007). The renaming of mental
retardation: Understanding the change to the term intellectual
disability. Intellectual and Developmental Disabilities, 45 (2),
116-124.
Sullivan, P. & Knutson, J. (2000). Maltreatment and
disabilities: A population-based epidemiological study. Child
Abuse & Neglect, 24 (10), 1257-1273.
Turnbull, R., Turnbull, A., Warren, S., Eidelman, S. &
Marchand, P. (2002). Shakespeare redux, or Romeo and Juliet
revisited: Embedding a terminology and name change in a
new agenda for the field of mental retardation. Mental
Retardation, 40 (1), 65-70.
Zigler, E., Balla, D., & Hodapp, R. (1994). On the definition
and classification of mental retardation. American Journal of
Mental Deficiency, 89 (3), 215-230.