Intellectual disability.

Intellectual disability (ID) or Intellectual Developmental Disorder (IDD, the ICD-11 equivalent term) is defined in the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition of the American Psychiatric Association as “a disorder with onset during the

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conceptual, social and practical domains” (APA, 2013, p. 33). Intellectual disability intersects with all five dimensions of functioning described by Wehmeyer et al. (2008).

The American Association on Intellectual and Developmental Disabilities (AAIDD) define intellectual disability as significant limitations in intellectual functioning and adaptive behaviours which affect the degree of autonomy and independence with which the person can function in their social world. It is evidenced before the age of 18. It is statistically

understood to include those persons with a measured intelligence quotient (IQ) two standard deviations below the mean (IQ 70 or lower) (Schalock et al., 2010). Due to limited autonomy and independence, people living with intellectual disability are understood to be at higher risk to human rights abuse, including sexual abuse.

Harris (2006) describes four approaches to defining intellectual disability that can be used:

1. The statistical model: which considers the psychometric test scores.

2. The pathological model: Emphasis is on adaptive functioning and specific causes of intellectual disability.

3. The social systems model: if so labelled by the social system, commonly the school.

4. The developmental model which assesses fluid intelligence and problem solving, more commonly used in intervention than definition.

He further includes three elements to a model of intelligence: conceptual intelligence, social intelligence and practical intelligence.

Greenspan, Switzky, and Woods (2011) argue for a different approach, asking the question: “what is unintelligent behaviour?” (p. 246). They suggest that an understanding, particularly in adults with intellectual disability, that people with intellectual disability behave in ways which put them at risk as their impairments limit their ability to recognise

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and avoid both physical (injury, illness) and social dangers (rejection, manipulation,

victimisation). The greater the degree of intellectual disability, the greater the unawareness of risk and the need for support and protection. They use this model to explain the social

vulnerability evidenced in the courts where they are either manipulated into confessing to crimes they have not committed or to participation in crime which they had little incentive to commit. They further argue that people with intellectual disability are “whole people” who cannot be fully understood in terms of their IQ scores, that academic IQ needs to be

integrated with social and practical aspects of intelligence, using the term “adaptive

intelligence”. As an example, they use the intellectual disability phenotype of Foetal Alcohol Spectrum Disorder (FASD) who often exhibit poor social and practical judgement skills in everyday life and have been found, on neuropsychological assessment, to have deficits in executive functioning. This is a helpful insight in terms of understanding vulnerability to sexual abuse for people with intellectual disability.

Greenspan and Woods (2014) argue for use of the ICD-11 category name of Intellectual Developmental Disorder (emphasis added) (IDD) rather than Intellectual Disability (ID), as the name returns the emphasis to brain development and neurological impairment (be that due to genetic, birth injury, FASD or other biological causes). They argue for “…redefining intellectual disability/IDD as a biologically based disorder marked by limitations in everyday reasoning and judgement, rather than as a purely functional disability marked by seemingly arbitrary ceilings on psychometric measures that generally fail to capture the taxonomic essence of the category” (p. 13). The DSM-5 states: “IQ test scores are approximations of conceptual functioning but may be insufficient to assess reasoning in real life situations and mastery of practical tasks…thus clinical judgement is needed in

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Schalock and Luckasson (2013) differentiate between an operational definition of intellectual disability based on the three criteria of: “limitations in intellectual functioning, behavioural limitations in adapting to environmental demands, and early age of onset” (p. 87). They describe a constitutive definition of intellectual disability, that “the construct of ID belongs within the general construct of disability…the process of disablement and its

amelioration…the extensive impact that societal attitudes, roles, and policies have on ways that individuals experience health disorders…the distinction between biological and social causes of disability has blurred…a social-ecological conception of ID emphasises the interaction between the person and the environment” (p. 88-89).

Thus intellectual disability is not a static trait, but can be variably defined and the influence of environment, appropriate social support, inclusion and recognition is formative. Appropriate support can strengthen functioning. Intellectual disability is a political issue which argues for appropriate policies and advocacy (Schalock, 2011).

2.2.1.3. Levels of severity in intellectual disability.

A significant shift in the last few years in specifying severity is that “…levels of severity are defined on the basis of adaptive functioning and not IQ scores, because it is adaptive functioning that determines the level of support required. Moreover IQ measures are less valid in the lower end of the IQ range” (APA, 2013, p. 33). Table 2.1. provides a

descriptive summary of conceptual, social and practical functioning at various levels of disability and the accompanying level of support needed.

Table 2.1.

Summary of Severity Levels for Intellectual Disability

Severity level Conceptual domain Social domain Practical domain

Mild • Preschool: there may

be no obvious delays

• Immature social relations.

• May be independent in terms of age appropriate personal

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Severity level Conceptual domain Social domain Practical domain (Needing intermittent

support)

• School age and Adults: Difficulties in reading, writing, arithmetic, time and money skills • Adults: Limited in abstract thinking, executive functioning, short term memory.

• Concrete approach to problems and solutions.

• Difficulty reading social cues.

• Difficulty with emotional regulation and appropriate behaviour. • Limited

understanding of social risk and immature social judgement.

care and helping with domestic tasks

• Needs assistance with more complex daily living tasks needing support in areas such as money management, health care, legal decisions.

• Do better in jobs that do not emphasise conceptual skills. May need support in employment.

Moderate

(Needing limited but consistent support)

• Marked lag in the development of conceptual skills.

• Slower learning and limitations of extent. • Need ongoing support or others to take full responsibility

• Marked differences to peers in social engagement. • Spoken language is the primary means of communication but less complex than that of peers. • Limited social judgement, reading of social cues and decision making ability.

• Capacity for friendships with peers limited by social and communication difficulties. • Ties to wider family and friendships need support

• May be independent in terms of personal care but needs ongoing teaching and reminders. • Household tasks can be achieved but need ongoing support.

• Protected employment. • Recreation, health care, money and time management need significant support.

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Severity level Conceptual domain Social domain Practical domain Severe

(Needing extensive support)

• Little to no understanding of written language, numbers and quantity, time or money. • Need extensive support for problem solving

• Speech is limited to simple sentences or phrases.

• Focus on the here and now and the everyday. • Relationships with family and familiar others give pleasure.

• Requires supervision for all activities of daily living. • Skill acquisition is ongoing.

Profound (Needing pervasive support)

• Often have co- occurring motor and sensory impairments.

• Conceptual process limited to physical world rather than symbolic processes.

• May develop some self-care, recreational and goal directed skills with support • Limited understanding of speech or symbolic gestures. • May understand simple instructions or gestures. • Self-expression through nonverbal, non- symbolic communication. • Relationships with well-known family, care givers and familiar others through gestural and emotional cues

• Dependent on others for all aspect of daily care, may be able to participate to limited extent.

• Music, walks, water activities, simple games all with support can be forms of

recreation.

Note. Adapted from the Diagnostic and Statistical Manual of Mental Disorders – Fifth Edition (2013) and

Luckasson et al. (2002)