Intellectual disability (ID) is characterized by limitations in intellectual functioning (IQ below 70) and adaptive behaviors that originate before age 18. It can be mild, moderate, severe or profound. Associated impairments include cerebral palsy, epilepsy, autism, and mental health disorders. Diagnosis requires testing intellectual functioning and adaptive skills. Common misunderstandings are that those with IDs are all the same, cannot learn or work, and should not be part of the community.

1. INTELECTUAL DISABILITY
DIFINITION, TYPES, COMPLICATIONS
&
COMMON UNDERSTANDING OF THE PROBLEM

2. DEFINITION.
 Intellectual disability is a disability characterized by significant
limitations in both intellectual functioning and in adaptive behaviour,
which covers many everyday social and practical skills. This disability
originates before the age of 18. ( AAIDD)
 intellectual disability means “significantly sub-average general
intellectual functioning, existing concurrently with deficits in
adaptive behaviour and manifested during the developmental period,
that adversely affects a child’s educational performance.” (IDEA,
2004)
 It means Intellectual disability is a condition diagnosed before age 18
that includes below-average intellectual function (Below 70 IQ) and a
lack of skills necessary for daily living.

3. INTELLECTUAL FUNCTIONING
 Intellectual functioning: also called intelligence—refers to general
mental capacity, such as learning, reasoning, problem solving, and so
on.
 One way to measure intellectual functioning is an IQ test. Generally,
an IQ test score of around 70 or as high as 75 indicates a limitation in
intellectual functioning.

4. ADAPTIVE BEHAVIOUR
 Adaptive behaviour is the collection of conceptual, social, and
practical skills that are learned and performed by people in their
everyday lives. (AAIDD; Schalock, Borthwick-Duffy, Buntinx, Coulter, &
Ellis, 2009)
 •Conceptual skills: Language and literacy; money, time, and number
concepts; and self-direction.
 •Social skills: Interpersonal skills, social responsibility, self-esteem,
gullibility, naïveté (i.e., wariness), social problem solving, and the
ability to follow rules/obey laws and to avoid being victimized.
 •Practical skills: Activities of daily living (personal care), occupational
skills, healthcare, travel/transportation, schedules/routines, safety,
use of money, use of the telephone.

5. CLASSIFICATION OF INTELLECTUAL DISABILITY
 There are many methods for classification of Intellectual Disabilities.
 but we will focus on four prominent methods here:
1. Degree of intellectual impairment.
2. Required supports.
3. Domains of disability.
4. Etiology.

6. 1:Degree of Intellectual Impairment
 Per the APA (2000);
1. An individual is classified as having mild intellectual disability if his or
her IQ level is 50 to approximately 70.
2. Moderate intellectual disability if his or her IQ level is 35 to
approximately 50
3. Severe intellectual disability if his or her IQ level is 20 to
approximately 35
4. Profound intellectual disability if his or her IQ level is below 20–25

7. 2: Required Supports
 The AAIDD takes a different approach in defining the degree of
severity of intellectual disability, relying not on IQ scores but rather
on the patterns and intensity of needed support i.e.
 Intermittent support
 Limited support
 Extensive support
 pervasive support
 The AAIDD classification marks a shift from an emphasis on degree of
impairment to a focus on the abilities of individuals to function in an
inclusive environment

8. 3: Domains of Disability
 Another way to classify intellectual disability is to use the terminology
developed by the National Centre for Medical Rehabilitation Research (Msall,
2005).
 This model defines five domains:
1. Pathophysiology focuses on the cellular, structural, or functional events
resulting from injury, disease, or genetic abnormality.
2. Impairment refers to the losses that result from the pathophysiological
event.
3. Functional limitation describes the restriction or lack of ability to perform a
normal function.
4. Disability is the inability to perform activities or limitation in the
performance of activities
5. Societal limitations focus on barriers to full participation in society.

9. 4: Etiology
 The epidemiology of intellectual disability suggests that there are two
overlapping populations:
1. Mild intellectual disability is more likely to be associated with racial,
social, and familial factors (Heikura et al., 2005; Leonard & Wen,
2002; Noble, Tottenham, & Casey, 2005)
2. Severe intellectual disability is more typically linked to a
biological/genetic origin (Ropers, 2008; Strømme & Hagberg, 2000;
Yeargin-Allsopp, Murphy, Cordero, Decouflé, & Hollowell, 1997).

10. Complications & Associated Impairments
 An intellectual disability is often accompanied by other impairments called
comorbid conditions.
 The prevalence of these associated impairments correlates with the severity
of the disability
 These comorbid conditions include;
1. cerebral palsy occurs in about 20% of children with ID (Cooper & van der
Speck, 2009) which may also be associated with feeding problems and failure
to thrive. Motor impairments are more prominent than cognitive impairments
in Cerebral Palsy.
2. Seizure disorders (epilepsy) also occur in about 20% of children with
ID(Cooper & van der Speck, 2009).
3. Communication disorders expressive and/or receptive language skills are
more delayed than nonverbal reasoning (Problem Solving) skills.

11. Complications & Associated Impairments
4. Hearing problems occur in about 4.5% of children with ID*.
5. Vision problems occur in about 2.2–26.8% of children with ID*.
6. Down syndrome occurs in 11.0% of children with ID*. Down syndrome is a set
of physical and mental traits caused by a gene problem that happens before
birth. Children who have Down syndrome tend to have certain features, such
as a short neck, flat face, small ears, slanting eyes, small mouth, short arms
and legs.
7. Fragile X occurs in 1.9% of children with ID*. Fragile X Syndrome is an
inherited condition characterized by an X chromosome that is abnormally
susceptible to damage, especially by folic acid deficiency.

12. Complications & Associated Impairments
8. Autistic Disorder occur in about 10.1% of children with ID*. A child with
autism appears to live in their own world, showing little interest in others and
a lack of social awareness. The focus of an autistic child is a consistent
routine and includes an interest in repeating odd and peculiar behaviours.
9. Pervasive Developmental Disorder (PDD) occur in about 7.1% of children
with ID. PDD also affects social interaction, communication, interests and
behaviour
10. ADHD/hyperkinetic disorder occur in about 9.5% of children with ID. ADHD is
neurodevelopmental condition characterized by developmentally
inappropriate levels of inattention and distractibility and/or hyperactivity and
impulsivity that cause impairment in adaptive functioning at home, school,
and in social situations.

13. Complications & Associated Impairments
11. Conduct Disorder (CD) occur in about 5.1% of children with ID*. An individual
with CD must demonstrate a pattern of callous and unemotional behaviour in
which other people’s rights are violated, norms are ignored, or rules are
broken, and it must have continued for at least 12 month
12. Oppositional Defiant Disorder(ODD) occur in about 12.4% of children with
ID*. Per APA (2011) there must be a pattern of negative, hostile, and defiant
behaviours in ODD. Children must have angry/irritable moods,
defiant/headstrong behaviours, and vindictiveness. (APA, 2011)
13. Anxiety disorder occur in about 17.1% of children with ID*. Anxiety disorders
include generalized anxiety disorder, panic disorder, social anxiety disorder,
OCD, and PTSD. (APA, 2011)
* Source: Osesburg, Dijkstra, Groothoff, Reijneveld, and Jansen (2011)

14. DIAGNOSIS OF IDs
 The diagnosis of intellectual disability should include tests for both the
components of IDs i.e. Intellectual functioning and Adaptive Behaviour
 Intellectual Functioning can be evaluated with an individual intelligence test .
 The most commonly used test in children are;
1. The Bayley Scales of Infant Development—Third Edition (BSID-III; Bayley,
2006)
2. The Stanford-Binet Intelligence Scales—Fifth Edition (Roid, 2003)
3. The Wechsler scales:
a) The Wechsler Preschool and Primary Scale of Intelligence—Third Edition
(WPPSI-III; Wechsler, 2002)
b) The Wechsler Intelligence Scale for Children—Fourth Edition (WISC-IV;
Wechsler, 2003).

15. DIAGNOSIS OF IDs
 In addition to testing intelligence, adaptive skills (including social
functioning) also should be measured.
 The most commonly used test of adaptive behaviour are;
1. The Vineland-II (Sparrow et al., 2005).
2. The Scales of Independent Behaviour—Revised (Bruininks, Woodcock,
Weatherman, & Hill, 1996)
3. The Adaptive Behaviour Assessment System—Second Edition (ABAS-II; Harrison
& Oakland, 2003).

16. Common Misunderstandings about IDs
 The following is a sampling of the many misconceptions that some people still
have about individuals with intellectual challenges.
 People with IDs are all the same.
 Children with IDs are a burden to their families.
 People with IDs cannot learn.
 It is not offensive to label them.
 Individuals with IDs should not be part of the community.
 Individuals with IDs have behaviours that cannot be understood.
 Adults with IDs cannot live independently.
 An individual with a IDs cannot be your friend.

17. Common Misunderstandings about IDs
 Those with IDs are not employable.
 Those with IDs do not have the same feelings as other people.
 People with developmental disabilities are not equals.