Abstract

The World Health Organization (WHO) is in the process of developing the 11th edition of the International Classification of Diseases (ICD–11). Part of this process includes replacing mental retardation with a more acceptable term to identify the condition. The current international consensus appears to be replacing mental retardation with intellectual disability. This article briefly presents some of the issues involved in changing terminology and the constraints and conventions that are specific to the ICD.

A regrettable yet predictable sociological phenomenon associated with the condition formerly known as mental retardation is stigma. In the evidence of the growing stigma associated with the name of this socially constructed condition, stakeholders indicated it was time to replace this term. That led to a process to identify a replacement term acceptable to all stakeholders, including individuals with the condition and their families. This is how we arrived at intellectual disability. Although known as a social construction, intellectual disability is a very real condition with very important health, education, and economic implications for all nations. One might argue that we can call the condition formerly known as mental retardation what we want. What is important, as stated in the goal for the current International Classification of Diseases ([ICD–10]; WHO, 1992) is that the term facilitates identification and communication. An important element in the development process of the upcoming edition of the ICD (ICD–11) is stakeholder acceptance (International Advisory Group for the Revision of the ICD–10 Mental and Behavioural Disorders [IAG], 2011). Otherwise, clinical validity of the ICD–11 will be seriously negated.

Most individuals in the general public do not give much thought to a condition's name. They may know spina bifida because of a family member, friend, classmate, or just general knowledge but might be less likely to know how the name of this condition was decided on. Spina bifida is known as a neural tube defect in which one or more of the vertebrae in the infant do not form completely and may result in an opening in the spinal column. The medical term for this condition, “spina bifida,” is derived from Latin spinus and bifidus meaning “spine” and “divided in two parts.” Even more people will probably know diabetes and know it as a disorder associated with increased sugar in the blood but, again, may be less likely to know the meaning of diabetes mellitus. It may seem odd to some that diabetes mellitus is actually a juxtaposition of a Latin and Greek word. One may understand the meaning when it is explained that diabetes originates from the Greek for “to pass through” because this condition was first identified by frequent urination. Mellitus is Latin and means sweet or honey and was added to diabetes when it was discovered that the urine of persons with diabetes has a sweet taste. Nowadays, diabetes mellitus is diagnosed using a routine blood analysis and the measuring of sugar levels in the blood.

In contrast with diabetes, spina bifida, and other health conditions, the condition previously known as mental retardation is a social construction. There is nothing wrong with a society defining disorders. A social construct is not a bad thing. Achieving a strictly neurobiological or genetically based diagnostic and classification system for many of the mental and behavioral disorders in the ICD–11 remains elusive (IAG, 2011). When Bogdan and Taylor (1994) asserted that “mental retardation” (i.e., intellectual disability) did not exist, what they were referring to was that there was no natural taxon for intellectual disability. In contrast with medical conditions, intellectual disability has many causes, including genetic, organic, social, environmental, or possibly an interaction of one or more of these. Socially constructed conditions exist because they allow us to identify a group of individuals who are in need of specialized study, support, or treatment. The Diagnostic and Statistical Manual ([DSM]; American Psychiatric Association [APA], 2000) and ICD–10 (WHO, 1992) contain many such conditions, what Greenspan (2006) has called “artificial taxons.” Some of these include, learning disorders, autism spectrum disorders, attention-deficit/hyperactivity disorder, depression, dementia, and many more.

The field of disabilities may envy the field of medicine for the longevity of terms such as diabetes, which has endured thousands of years. However, unlike diabetes, there have been several terms adopted and abandoned for the developmental condition characterized by low intellectual functioning and adaptive behavior, for now, known as intellectual disability. The condition known as intellectual disability has gone through several iterations, where a new term is agreed on, followed by a period of use, then the term eventually acquires negative stigma, is abandoned, and the process of securing of a new term begins.

Most recently, the term intellectual disability has replaced mental retardation. The American Association on Intellectual and Developmental Disabilities (AAIDD) published an article preceding the development of the 10th edition of its terminology and classification manual in which Schalock and colleagues (2007) affirmed unequivocally that

[t]he term intellectual disability covers the same population of individuals who were diagnosed previously with mental retardation in number, kind, level, type, and duration of the disability, and the need of people with this disability for individualized services and supports. Furthermore, every individual who is or was eligible for a diagnosis of mental retardation is eligible for a diagnosis of intellectual disability. (p. 120)

This effort from Schalock and colleagues (2007) was intended to make very clear that this term intellectual disability was not designating a new condition but was replacing an obsolete term being abandoned because of its acquired pejorative value.

The adoption of the term intellectual disability in the first national classification system occurred in the 11th edition of AAIDDS Intellectual Disability: Definition, Classification, and Systems of Supports (Schalock et al., 2010), although the organization had officially changed its name in 2005 from the American Association on Mental Retardation to the American Association on Intellectual and Developmental Disabilities. This choice in name change (i.e., “intellectual and developmental disabilities”) for the interdisciplinary professional society was meant to better represent breadth of study of its membership, people with an intellectual disability and people with developmental disabilities and not an indication of a new classification term. It should be noted that the International Association for the Scientific Study of Mental Deficiencies had changed its name many years prior to the International Association for the Scientific Study of Intellectual Disabilities.

In October 2010, the President of the United States signed Rose's Law, which essentially authorized the search-and-replace of “mental retardation” for “intellectual disability” in federal laws and statutes, including Individuals with Disabilities Education Act, Rehabilitation Act, Public Health Service Act, and others (S. 2781—111th Congress, 2009). Following suit, the Social Security Administration announced it was moving forward in replacing mental retardation with the term intellectual disability (Social Security Administration, 2013).

Classification Systems

There are three widely used systems of classification that name, define, and establish diagnostic criteria for intellectual disability: ICD–11 (anticipated for 2015), DSM (5th edition scheduled for release in May 2013), and the American Association on Intellectual and Developmental Disabilities (currently in its 11th edition). The ICD–10 (WHO, 1992) system identifies and provides diagnostic codes for more than 10,000 health conditions (medical diseases and behavioral/mental disorders), and the DSM–IV–TR (APA, 2000) describes and defines more than 300 mental disorders, of which, intellectual disability is one. The AAIDD terminology and classification system (Schalock et al., 2010) focuses its more than 250-page manual solely on the condition known as intellectual disability.

Prior to the most recent revision and updates to the AAIDD manual (Schalock et al., 2010), all three classification systems were in agreement on the term (i.e., mental retardation) and the tri-pronged diagnostic criteria for the condition previously known as mental retardation (i.e., significant deficits in intellectual functioning, significant deficits in adaptive behavior, and onset during the developmental period). The AAIDD adopted the term intellectual disability in its most recent revision of its diagnostic and classification manual (Schalock et al., 2010). Although the actual text of the DSM–5 will be embargoed until its release in May 2013, it is anticipated that the APA will also replace mental retardation with intellectual disability (APA, 2013; Diament, 2013). The DSM–5 will have a parenthetical that will read “intellectual disability (intellectual developmental disorder).” It is unclear whether the official DSM–5 term will necessitate inclusion of the parenthetical. If so, it will make the DSM–5 term quite cumbersome and confusing. The parenthetical has been included in the DSM–5 to reference the term intellectual developmental disorders (plural) currently in the draft proposal of the ICD–11, which is under review by the WHO. The justification provided by the APA for including the parenthetical is to align the DSM–5 with the ICD–11 proposed name change for mental retardation, but they also stated “to reflect deficits in cognitive capacity beginning in the developmental period” (APA, 2013, p. 1). This rationale appears incongruent with the stated desire of the DSM–5 authors to “de-emphasize” the importance placed on IQ scores (APA, 2013). Also, age of onset continues to be one of the three diagnostic criteria, clearly demarking the condition from adult onset disorders (e.g., dementia). And why exclude “adaptive behavior” from the parenthetical?

The WHO has received a completed draft proposal from the Neurodevelopmental Disorders working group tasked with revising mental retardation. The development of the ICD–11 is entering its final phase, which is a two-year period of stakeholder consultation and field trials that may very well result in changes to the proposal (Tassé, Luckasson, & Nygren, 2013). If the ICD–11 selected terminology and diagnostic criteria differ significantly from the AAIDD manual (Schalock et al., 2010) and DSM–5 (APA, 2013), this would result in major confusion regarding global healthcare services and statistics, disparities in the number of individuals identified with intellectual disability and access to treatment.

WHO Conundrum

The ICD–10 defined mental disorders as “a clinically recognizable set of symptoms or behaviour associated in most cases with distress and with interference with personal functions,” and this definition will remain in use in the ICD–11 (IAG, 2011). The WHO published a companion taxonomy system to the ICD–10 called the “International Classification of Functioning” ([ICF]; WHO, 2001). The ICF takes the diseases and disorders found in the ICD system and applies a comprehensive system of classification across several domains, including impairment, activity limitations, and participation restrictions. The ICF has an overall goal of providing a classification system for the ICD–10 health conditions and shifts from a focus on the diagnosis to its impact on the person's activity and participation in the community. Disability is defined by the ICF as the outcome of an interaction between a person's health condition and his or her social and physical contextual factors that result in impairments and restrictions in activities and participation (WHO, 2001). The ICD system does not define or classify disabilities; rather, it defines diseases and disorders that may or may not result in a disability.

The AAIDD has long defined intellectual disability as a disability and not just as a health condition (Luckasson et al., 1992; Luckasson et al., 2002; Schalock et al., 2010). An intellectual disability may or may not result from a health condition. In almost 40% of cases, the etiology of intellectual disability is unknown (APA, 2000).

Herein lies the conundrum for the WHO regarding the ICD–11 because intellectual disability is not clearly a medical disease or mental illness (Salvador-Carulla, Rodriquez-Blázquez, & Martorell, 2008), and, as the currently accepted name implies, it is conceptualized as a disability. Regardless, the term used to replace mental retardation in the ICD–11 should be consistent with established and current international practice and thus must be inclusive of “intellectual disability.”

Conclusion

The ICD is a compendium of descriptions and diagnostic guidelines of all known health conditions, including diseases and disorders. The ICD is developed to be used in all 193 member countries of the WHO. It may matter less what we call the condition previously known as mental retardation than making certain it is called, defined, and counted in the same manner anywhere around the world. This is the fundamental goal the WHO strives for the ICD system.

The WHO has the enormous responsibility of putting forth a classification system that can be implemented worldwide, from Calcutta to Lisbon to Moscow to Shanghai to New York City. The ICD–11 has conceived a polynomial medical neologism that is the juxtaposition of three words (i.e., intellectual + developmental + disorder; Salvador-Carulla et al., 2011). This proposal was put forth, in lieu of the widely accepted term intellectual disability. The use of the never-heard-before term of intellectual developmental disorders would result in certain global confusion and should be averted.

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Author notes

Author:

Marc J. Tassé (marc.tasse@osumc.edu), The Ohio State University Nisonger Center—UCEDD, 1581 Dodd Drive, Columbus, OH 43210