Intellectual Disability
Currently there is not a standard or universal terminology employed in the field of intellectual disability. However the term ‘intellectual disability’ is now emerging as the preferred term for what is referred to as ‘mental retardation’ in the United States and ‘learning disability’ in the United Kingdom. In Ireland the term intellectual disability has become the more utilised by professionals in the field.
Intellectual disability is considered as a lifelong condition with multiple causes and origins. According to the American Psychiatric Association, there is no specific personality or behavioural characteristics that are specific to it. Severe levels of intellectual disability or syndromes associated with a specific phenotype, such as Down’s Syndrome, can be identified early in childhood. Less severe levels of intellectual disability may not become apparent until the school years when children may fail to reach certain developmental milestones.
Before the advent of intelligence testing, there was no method of diagnosing intellectual disability. However in the early 1900’s the concept of intellectual quotient (IQ) became the main criteria for diagnosing intellectual disability and this indicated that people with intellectual disability were incapable of learning or acquiring anything more than basic cognitive skills. By the 1960s however a new shift in emphasis emerged with a greater focus on ‘adaptive behaviour’ indicating that intellectual disability comprised not only of a deficit in intellectual capacity but also in social and adaptive functioning.
Adaptive functioning is defined as the effectiveness to which an individual meets standards of personal independence and social responsibility expected for his or her age and cultural background. As a consequence of this new emphasis on adaptive functioning intelligence quotient alone is no longer sufficient criteria for determining intellectual disability. Adaptive functioning must also be assessed. These skills include self-care, social skills, use of community facilities, health & safety, engagement in
The Diagnostic and Statistical Manual of Mental Disorders (DSM IV) states that ‘this mental disorder is diagnosed in individuals who, from whatever cause have intelligence below an arbitrary level beginning before adulthood and whose adaptive functioning is impaired in any of a variety of areas’ By arbitrary we mean a specific score or boundary according to assessment.
The criteria specified in this manual (which is widely used by psychiatrists and psychologists) for diagnosing what it refers to as ‘mental retardation’ is:
- A. Significantly subaverage intellectual functioning: an IQ of approximately 70 or below on an individually administered IQ test (for infants, a clinical judgement of significantly subaverage intellectual functioning).
- B. Concurrent deficits or impairments in present adaptive functioning (i.e. the person’s effectiveness in meeting the standards expected for his or her age by his or her cultural group) 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.
- C. The onset is before 18 years.
The manual also further diagnoses the degree of severity reflecting level of intellectual impairment:
- Mild Mental Retardation: IQ level 50-55 to approximately 70 (318.0)
- Moderate Mental Retardation: IQ level 35-40 to 50-55 (318.1)
- Severe Mental Retardation: IQ level 20-25 to 35-40 (318.2)
- Profound Mental Retardation: IQ level below 20 or 25 (319)
- Mental Retardation, Severity Unspecified: When there is strong presumption of Mental Retardation but the person’s intelligence is untestable by standard tests.
We need to be reminded that the term ‘mental retardation’ has become very much unacceptable throughout the world and particularly in Ireland. Likewise the term ‘handicap’ which was also commonly utilised in Ireland in the 1970’s and 1980’S is less used nowadays. However the classification as outlined above is very commonly applied by professionals in this area, with the words ‘intellectual disability’ in place of ‘mental retardation’.
