Attention deficit hyperactivity disorder (ADHD) is typically a life-long condition that results in functional limitations. Function limitations may be mild or they can be quite severe, depending on the severity and management of ADHD symptoms and comorbidities. Workplace settings present a wide variety of diverse occupational research challenges. Because the impact of the condition will vary from setting to setting, obtaining a consistent and reliable picture of adaptive or maladaptive functional performance directly attributable to ADHD is difficult.
While there seems to be evidence of many success stories of adults with ADHD who are self-employed and have found a controllable « niche » that they flourish in, most of those seeking entry or upward mobility in the workplace have to live and play by the rules of a world that has little understanding or sensitivity of the emotional impacts of having this hidden disability and the costs to the individual trying to « keep it together ».
The intent of this paper is twofold. First, it seeks to familiarize the reader with the concepts of impairment, disability, handicap, functional limitations, functional capacities, and functional assessment. Second, provide a quick review of disability models (or disablement models), and third, to discuss the concept of Functional Limitation (FL) in relation with ADHD, and with disabilities models.
MODELS OF DISABILITY
Disablement Model is a conceptual explanation of the process and underlying mechanisms by which disease, injury or birth defect impacts a person’s ability to function (perform their expected role in society). Different contributions could be divided into three groups of models : models in which disability is an attribute of the person, models in which disability is related to the environment, and models in which disability is linked to the person-environment relationship.
Models of disablement are helpful in understanding the process of how a person loses abilities, and are important in the selection of interventions to address those losses. Models of disablement are tools for defining impairment and, ultimately, for providing a basis upon which government and society can devise strategies for meeting the needs of disabled people. Models of disablement define disability, determine casual and responsibility attributions, influence professional practice, drive payment systems, and guide legislation (Dembo, 1982; Hahn, 1993; Nagi, 1969; Zola, 1989). Models of disability are the underlying structure for large, complex diagnostic/defining systems. Models of disablement refers to systems of definitions and theories about human disability that are used to provide a framework for discussion or to explain disabilities in relation to clinical diagnosis, rehabilitation medicine, employment issues, public policy-making, and similar concerns.
Surprisingly, the power of models of disablement is rarely acknowledged or addressed; nor, are these models questioned or challenged (Gill, Kewman, & Brannon, 2003; Harper, 1991; Pledger, 2003). Indeed, most practitioners are only marginally aware that there are other models and that patients/clients/consumers may, and often do, subscribe to a different model. A therapeutic alliance, therefore, is difficult to establish if the professional and client define the disability differently and, as a result, envision different treatments and services. Most practitioners function in the way in which they have been educated and trained (Bauman & Drake, 1997; Bluestone, Stokes, & Kuba, 1996; Gill et al., 2003; Hogben & Waterman, 1997; Kemp & Mallinkrodt, 1996; Parsons, Hernandez, & Jorgensen, 1998).
The literature is replete with attempts to apply a wide variety of sociological and psycho-sociological theories to disablement phenomena. Disablement has been explained in terms of deviance theories, labeling and functionalist theories, symbolic interactionalism, somatopsychological and attitude theories, marxist and
other materialistic theories, and more recently feminist theories, postmodern interpretations and many others.
GROUPS OF DISABLEMENT MODEL :
- The Charity Model of Disability : The charity model looks at disability as a personal tragedy ;
- The Moral/Religious Model of Disability : The religious model views disability as a punishment inflicted upon an individual or family by an external, usually supernatural, force. Sometimes the presence of « evil spirits » is used to explain differences in behavior, especially in conditions such as schizophrenia. Acts of exorcism or sacrifice may be performed to expel or placate the negative influence, or recourse made to persecution or even death of the individual who is « different ». In some cases, the disability stigmatizes a whole family, lowering their status or even leading to total social exclusion. Or it can be interpreted as an individual’s inability to conform within a family structure. Conversely, it can be seen as necessary affliction to be suffered before some future spiritual reward. ;
- The Medical Model of Disability (also known as the biomedical model, and as the functional-limitation model): The medical model of disability has a long history, is the most well-known to the general public, and carries with it the power and prestige of the well-established medical profession. This model, rooted in the scientific method and the benefactor of a long tradition, has had dominance in shaping the understanding of disability.The medical model for many years has been the dominant approach to disability. The medical model of disablementhas an emphasis on pathology-based causes of impairments that can lead to a disability. This model reflects a treatment approach to the disability with the aim of ameliorating the pathology or impairment in order to cure or lessen the disability. Clinically, the medical model guides the selection of interventions toward the aim of lessening or curing the pathology or impairment and its resulting functional limitation.The medical model assumes that the first step solution is to find a cure or – to use WHOterminology – make disabled people more « normal ». This invariably fails because disabled people are not necessarily sick or cannot be improved by remedial treatment. The only remaining solution is to accept the « abnormality » and provide the necessary care to support the « incurable » impaired person. Policy makers are limited to a range of options based upon a program of rehabilitation, vocational training for employment, income maintenance programs and the provision of aids and equipment.The medical model holds that disability results from an individual person’s physical or mental limitations, and is largely unconnected to the social or geographical environments. It is sometimes referred to as the Biological-Inferiority or Functional-Limitation Model. This model locates the « problem » of disability in the deviant body of the individual, rather than in society itself or in the way the deviant mind or body is perceived. When people such as policy makers and managers think about disability in this individual way they tend to concentrate their efforts on ‘compensating’ people with impairments for what is ‘wrong’ with their bodies by targeting ‘special’ welfare benefits at them and providing segregated ‘special’ services for them and so on. The medical model of disability also affects the way disabled people think about themselves. Many disabled people internalize the negative message that all disabled people’s problems stem from not having ‘normal’ bodies. Disabled people too can be led to believe that their impairments automatically prevent them from participating in social activities.
- The functional-limitation model (medical model) has dominated the formulation of disability policy for years. Although we should not reject out-of-hand its therapeutic aspects which may cure or alleviate the physical and mental condition of many disabled people, it does not offer a realistic perspective from the viewpoint of disabled people themselves. To begin with, most would reject the concept of being « abnormal ». Also, the model imposes a paternalistic approach to problem solving which, although well intentioned, concentrates on « care » and ultimately provides justification for institutionalization and segregation. This restricts disabled people’s opportunities to make choices, control their lives and develop their potential.
- The biomedical modelhas had dominance in shaping the public’s understanding of disability because of the following factors: a) the long history of the Biomedical model, b) its reliance on the prestigious and authoritative academic disciplines of medicine and science, c) its strong explanatory power, and 4) the public’s intuitive understanding of medical diagnoses. Moreover, many disability scholars feel that the dominance of the Biomedical Model will continue, and increase, as the profession of medicine evolves into more specializations. This model has fragmented the disability community into diagnostic categories and thus robbed them of their collective history and memory. The rather dated criticisms of the biomedical Model of Disability, including the pathologization, categorization, objectification, and privatization of disability.Due to this « individualization, » « privatization, » and « medicalization » of disability, the Biomedical Model has remained silent on issues of social justice. Until recently, the biomedical model itself has been silent on issues of social justice. While no one believes that medical professionals deliberately created injustice and discrimination, nonetheless, the result has been injustice. Scholars feel that disability has been “misrepresented” as only a health concern and because of this discrimination and prejudice based on disability result, but also frequently remain unrecognized. Further, to the general public, this discrimination and prejudice does not appear to be prejudice and discrimination because it is the medical professions who have been given the mandate to respond to all the needs of people with disabilities.Defining disability as solely a medical concern that requires high levels of expertise, training, and technology also lends scientific credibility to the idea that all of the difficulties experienced by people with disabilities are the result of their physical abnormalities or physical inferiority. Higgins (1992) summarized this when he remarked that we make people with disabilities foreigners in their own country. The well-defined normative basis of disability of the biomedical model also relieves society of any need to provide accommodation. The entire focus is on changing the individual (rehabilitation) rather than changing the environment (accommodation). In the biomedical model, disability is thought to be dysfunction, abnormality, pathology, disease, or defect. Simply stated, it is better not to have a disability. Disability is deviance, not a valued difference. Disability is defined as an observable deviation from biomedical norms of structure or function that directly results from a disease, trauma or other health condition (Boorse, 1975, 1977). Goffman (1961, 1963) describe the process of stigmatizing and the creation of “deviance”. Therefore, individuals with a disability understand that they belong to a devalued group, regardless of their individual attributes, achievements, or resources. Often individuals with disabilities eventually accept the disabled role of inferiority and deviance. In the biomedical model, pathologizing and privatizing disability was another way in which to effectively absolve “society” from any responsibility to deal with disability issues.The biomedical model has provided the basis for much of the legislation that mandates services for people with disabilities and also guides the reimbursement and payment systems of government agencies and insurance companies (Berkowitz & Hill, 1986; Wolfensberger, 1972; Zola, 1993). Therefore, both the services and funding the individual with a disability receives are based on the biomedical model. The profession of medicine has, for centuries, been based on the two outcome paradigm of cure or death and vestiges of this paradigm are reflected in payment systems. Therefore, after medical stabilization, much of the funding is withdrawn, not taking into consideration the individual’s greatest needs (Yelin, 1992). Nonetheless, disabilities are chronic conditions which require care and not cure. Health maintenance, patient education, maintaining the highest quality of life, avoiding secondary conditions, and responding to interaction of the disability with the aging process are all medical services that are necessary for someone with a disability, but typically are not funded or underfunded. Simply because the Biomedical Model does not take the environment into consideration, payers will not see the individual benefits (or overall social benefit) of paying for services such as marital counselling or other types of counselling. Environmental and social interventions frequently are not funded. Psychiatric disabilities, which are highly dependent upon the environment of the individual, are not well-funded. Such environmental accommodations could render the individual highly functional (Wright, 1991). ;
- The Rehabilitation Model of Disability : The rehabilitation model is similar to the medical model; it regards the person with a disability as in need of services from a rehabilitation professional who can provide training, therapy, counselling or other services to make up for the deficiency caused by the disability. Persons with disabilities have been very critical of both the medical model and the rehabilitation model. While medical intervention can be required by the individual at times, it is naive and simplistic to regard the medical system as the appropriate locus for disability related policy matters. Many disabilities and chronic medical conditions will never be cured.
- The Expert/Professional Model of Disability : The expert/professional model has provided a traditional response to disability issues and can be seen as an offshoot of the Medical Model. Within its framework, professionals follow a process of identifying the impairment and its limitations (using the Medical Model), and taking the necessary action to improve the position of the disabled person. This has tended to produce a system in which an authoritarian, over-active service provider prescribes and acts for a passive client.
- The Social Model of Disability: The social model views disability as a collection of factors and conditions, many of which are created by society and act as barriers to the individual’s participation in society. The Social Model views disability as a consequence of environmental, social and attitudinal barriers that prevent people with impairments from maximum participation in society.The social modelof disability makes the important distinction between ‘impairment’ and ‘disability’. So, in a social model of disability the key definitions are: Impairment – An injury, illness, or congenital condition that causes or is likely to cause a long term effect on physical appearance and / or limitation of function within the individual that differs from the commonplace. Disability – The loss or limitation of opportunities to take part in society on an equal level with others due to social and environmental barriers.The social modelfocuses on the need for social interventions to enable all persons to participate in society regardless of their abilities. This model guides the selection of interventions toward the aim of lessening the disability, which is a result of both a physical condition as well as social and/or environmental barriers.The social modelhas been worked out by disabled people who feel that the individual model does not provide an adequate explanation for their exclusion from mainstream society – because their experiences have shown them that in reality most of their problems are not caused by their impairments, but by the way society is organized. The social activists and advocates for persons with disabilities have argued that disablement is a political issue, a matter of basic civil rights. Persons with disabilities are a social minority who have been systematically discriminated against in all areas of life (Eisenberg et al., 1982; Barnes, 1991). The limitations they face in education, employment, housing and transportation are not the products of their medical condition, but of social attitudes of neglect and stereotypical images about their capacities and needs (Gartner and Joe, 1987). Since the source of the disadvantage is a failure of the social environment, the appropriate strategies for remedying this are political: change attitudes, change policies and laws.The social modelthus takes account of disabled people as part of our economic, environmental and cultural society. The barriers that prevent any individual playing a part in society are the problem, not the individual. Barriers still exist in education, information and communication systems, working environments, health and social support services, transport, housing, public buildings and amenities.The social modelhas been developed by disabled people in response to the medical model and the impact it has had on their lives. Under the social model, disability is caused by the society in which we live and is not the ‘fault’ of an individual disabled person, or an inevitable consequence of their limitations. Disability is the product of the physical, organizational and attitudinal barriers present within society, which lead to discrimination. The removal of discrimination requires a change of approach and thinking in the way in which society is organized.Unfortunately very little empirical research has been done on the fundamental question of how intrinsic features of an individual interact with features of the social environment to produce disablement. How precisely does the social environment create disablement? Should we expect patterns of disadvantage linked to special physical or mental conditions? How do we identify which aspects of the social environment are responsible for disadvantage? Which interventions will make a difference, and can we measure the improvement? ;
- The Sociopolitical Model of Disability : the sociopolitical model sees disability as a result of environmental and social factors: people with impairments are disabled by barriers in society, by its structures and norms. Advocates of the Sociopolitical Model believe that much of the prejudice and discrimination experienced by people with disabilities occurs not in spite of the Biomedical Model, but because of the Biomedical Model. The Sociopolitical Model asserts that the Biomedical Model, by dividing individuals into groups based on diagnostic categories or functional traits, has effectively fragmented people with disabilities into competing interest groups. The various disability groups must compete for tangible resources and services. ;
- The Biopsychosocial Model of Disability : the biopsychosocial model is being articulated that embraces aspects of social, biological and psychological factors thus recognizing the complexities of simplistic interpretation and definition ;
- The Economic Model of Disability : Under the economic Model, disability is defined by a person’s inability to participate in work. It also assesses the degree to which impairment affects an individual’s productivity and the economic consequences for the individual, employer and the state. Such consequences include loss of earnings for and payment for assistance by the individual; lower profit margins for the employer; and state welfare payments.The Economic Model is used primarily by policy makers to assess distribution of benefits to those who are unable to participate fully in work. In recent years, however, the preoccupation with productivity has conflicted with the application of the Medical Model to classify disability to counter fraudulent benefit claims, leading to confusion and a lack of co-ordination in disablement policy. ;
- The Functional Model of Disability — Interactionnal Approach : In Great Britain, sociologists sought their explanations outside of the more individualistic, American approach, adopting more overtly political theoretical accounts. The model also arose within social psychology (Meyerson, 1948, 1988) only to be labelled by some researchers the “interactive” model — a name likely derived from the internationalist school of American sociology (Lemert,1962) — and by others the “environmental” approach, to disability (Amundson, 1992; Bickenbach, 1993; Imrie, 1997) ;This relationship has been described as that of fixer (the professional) and fixee (the client), and clearly contains an inequality that limits collaboration. Although a professional may be caring, the imposition of solutions can be less than benevolent. If the decisions are made by the « expert », the client has no choice and is unable to exercise the basic human right of freedom over his or her own actions. In the extreme, it undermines the client’s dignity by removing the ability to participate in the simplest, everyday decisions affecting his or her life.
- The Customer/Empowering Model of Disability : The customer/empowering model is the opposite of the expert/professional. Here, the professional is viewed as a service provider to the disabled client and his or her family. The client decides and selects what services they believe are appropriate whilst the service provider acts as consultant, coach and resource provider. Recent operations of this Model have placed financial resources into the control of the client, who may choose to purchase state or private care or both. ;
- The Administrative Model of Disability : The administrative model focuses upon disability as an assessment process for identifying needs. ;
THERE ARE MANY DISABLEMENT MODEL :
- Nagi’s Disablement Model [Saad Nagi, 1965] (pathology -> impairment -> functional limitations -> disability) : Uni-dimensional (pathology-based) and unidirectional model of disability only, does not account for impairments and functional limitations not due to pathology, and does not consider societal barriers: architectural, attitudinal. Active pathology refers to any interruption or interference with normal processes, and efforts of the organism to regain normal state. Impairment is defined as any loss or abnormality of anatomic, physiologic, mental, or emotional structure or function. Functional limitation is defined as a limitation in performance at the level of the whole organism or person. Disability then applies to a limitation in performance of socially defined roles and tasks within a sociocultural and physical environment. In the 1960s and 1970s, Saad Z. Nagi developed an influential model of disability based on his research on rehabilitation outcomes (Nagi, 1964, 1965, 1976, 1987). Nagi’s concepts strongly influenced other models of disability, including those of the WHO and the NCMRR. ;
- A second revision of Nagi’s model, Verbrugge and Jette’s Model of the Disablement Process[Verbrugge and Jette] : While integrating this model with I.C.I.D.H., they developed a new disablement model in order to describe how chronic and acute conditions affect functioning in specific body parts, mental function and daily life, and the role of personal and environmental factors in disablement (Verbrugge and Jette, 1994). Verbrugge and Jette elaborated on Nagi’s model in “an attempt to attain a full sociomedical framework of disablement, which they defined as the impact that chronic and acute conditions have on functioning of specific body systems and on people’s abilities to act in necessary, usual, expected, and personally desired ways in their society” (Jette, 2006:729). Altman (2001) notes that Verbrugge and Jette focused on task orientation, while Nagi focused more on role orientation toward limitation. As already noted, Verbrugge and Jette accepted the elements of Nagi’s model: active pathology, impairment, functional limitation, and disability. They operationalized the Nagi model by identifying various types of necessary, usual, expected, and/or personally desired roles and activities under Nagi’s concept of disability that should be tracked and measured. These included (Verbrugge and Jette, 1994). In addition Verbrugge and Jette (1994) tried to make the model more dynamic by identifying factors that affect what they called the “disablement process.” They posited three sets of variables that affected the “pathway” to disablement of a given individual. These were:Risk Factors: Risk factors are “predisposing phenomena that are present prior to the onset of the disabling event that can affect the presence or severity of the disablement process. Examples include sociodemographic background, lifestyle, and biologic factors.” ;Indra-individual Factors : Indra-individual factors “operate within a person, such as lifestyle and behavioral changes, psychosocial attributes and coping skills, and activity accommodations made by the individual following onset of a disabling condition.” ;Extra-individual Factors : Extra-individual factors are in the external “physical as well as the social context in which the disablement process occurs. Environmental factors relate to the social as well as the physical environmental factors that bear on the disablement process. These can include medical and rehabilitation services, medications and other therapeutic regimens, external supports available in the person’s social network, and the physical environment.”Verbrugge and Jette stimulated research into the impact of risk factors, intra-individual factors, and extra-individual factors on impairment, functional limitation, and disability and how they influence the disablement process ;
- A third revision of Nagi’s model, Institute of Medicine’s (IOM’s) Enabling-Disabling Model[Brandt and Pope, 1997, IOM] (pathology -> impairment -> functional limitations -> disability) : In 1997, an IOM committee issued a report, Enabling America: Assessing the Role of Rehabilitation Science and Engineering, which responded to a congressional request for an assessment of rehabilitation research and technology development efforts. The report extended the 1991 IOM model by making “clear reference to the importance of the environment in causing, preventing, and reducing disability” (IOM, 1997:1). The IOM report added several dimensions to the Nagi model. First, it proposed three interacting risk factors—biological, environmental (social and physical), and lifestyle/behavioral—that affect each element of the disabling process: pathology, impairment, functional limitation, and disability. Second, it added impact on quality of life as a part of the disabling process (IOM, 1991:84-91). In effect, it added another component to Nagi’s model—features of the social and physical setting affecting an individual’s degree of disability that could be targeted for change. The IOM report helped bring Nagi’s conceptual model of disability to a wider audience and helped stimulate research on the environmental aspects of the disablement process.The committee explicitly adopted the elements of Nagi’s disability model (but called them “components of the disabling process” in the report)—i.e., pathology, impairment, functional limitation, and disability—with disability defined as “a limitation in performing certain roles and tasks that society expects of an individual” (Table 2-1). The IOM report focused on the “enabling process,” by which it meant efforts to reduce disability. Enabling could be accomplished by either restoring function in the individual (i.e., traditional rehabilitation) or expanding access to the environment, or both. The report also introduced the notion of secondary conditions as “any additional physical or mental health condition that occurs as a result of having a primary disabling condition” and that “quite often increase the severity of an individual’s disability and are also highly preventable” (IOM, 1997:3-5).According to the report, “the committee enhanced the 1991 IOM model to show more clearly how biological, environmental (physical and social), and lifestyle/behavioral factors are involved in reversing the disabling process, i.e., rehabilitation, or the enabling process. The enhancements include bidirectional arrows between the various states of the enabling–disabling process to indicate that the disabling process (described in the 1991 IOM model) can be reversed with proper interventions (i.e., the enabling process)” (IOM, 1997:6).The graphic representation of the new IOM model did not include a box for “disability,” in an effort “to help clarify the fact that disability is not inherent in the individual, but rather is a product of the interaction of the individual with the environment” (IOM, 1997:8). The report proceeded to recommend research and engineering needs and opportunities by domain: pathology and impairment research, functional limitation research, and disability research. Disability research would be “explicitly focused on the effects of the environment in producing or reducing disability” (IOM, 1997:12).In the report, the committee noted that the 1991 IOM model had some shortcomings. First, disability was depicted in the 1991 model as a linear process, which was fine for the 1991 report’s focus on ways to prevent disability but did not allow for reversal of disability through rehabilitation. Second, the earlier model gave a “limited characterization of the environment and the interaction of the individual with the environment.” Third, the 1991 model provided a limited “representation of societal limitations” (IOM, 1997:67).The International Classification of Impairments, Disabilities and Handicaps (ICIDH) [Philip Wood, WHO, 1980] (disease -> impairment -> disability -> handicap):
- In 1976, the World Health Assembly of the World Health Organization (WHO) approved for publication a classificatory instrument incorporating a version of the social model. The result, eventually published in 1980, was the International Classification of Impairments, Disabilities and Handicaps(ICIDH) (World Health Organization, 1980). Here was an international classification of disablement, suitable for research and a myriad of other uses, that appeared to embody the insights of the social model.The underlying biopsychosocial model represents a synthesis of medical and social models, rather than a mere adoption of the social approach. The ICIDH made conceptual distinctions, based on Nagi, among impairment, functional limitations (which, however, WHO called “disability”), and disability (called “handicap” by WHO), which allowed recognition that disability is based not just on the attributes of the individual (the medical model) but also on the interaction between the person and society (the biopsychosocial model). The disease is defines as the intrinsic pathology or disorder. Impairment is defined as any loss or abnormality of psychological, physiological, or anatomical structure or function at organ level. Disability refers to any restriction or lack of ability to perform an activity in normal manner. Handicap then applies to disadvantage due to impairment or disability that limits or prevents fulfilment of a normal role [depends on age, sex, sociocultural factors] for the person. On the negative side, the ICIDH used the word “handicap” to label the result of the interaction between the person and the social setting. This label seemed to perpetuate the idea that the problem is more the inability of the person to fit into usual social roles rather than restrictions imposed by environmental barriers and social attitudes, which could be modified to enable an impaired person to participate in work and other normal activities. The model was also still medically based (i.e., diseases, injuries, or other disorders result in impairment, which cause functional limitations, which, in turn, reduce the person’s ability to participate in society). This did not recognize the complexity of the disablement process, especially the role of contextual factors, or the fact that the correlations between degree of impairment, extent of functional limitation, and level of disability are low.Among the many uses of the ICIDH discussed in the literature are health information surveying (Bonte, 1986), population studies (Chamie, 1995), rehabilitative outcomes measurement (De Kleijn-de Vrankrijker, 1989), research on home care for the elderly (Rusinowitz et al., 1993) and psychiatric research (Wiersma, 1986).Yet, despite its promise, almost from its first appearance critics have argued that the ICIDH and it’s model of disablement are deeply flawed (Fougeyrollas, 1995). Despite the attempt to offer a non medical model of disablement, the promise was never fully, or clearly, realized. The root problem was a subtle ambiguity of language that undermined the intended model. Try as the drafters might to insist that disabilities exist because of social expectations of normal performance and that handicaps are socially constructed disadvantages, they persisted in using language that suggest a very different picture : Disadvantage accrues as a result of [the individual] being unable to conform to the norms of his universe. Handicap is thus a social phenomenon, representing the social and environmental consequences for the individual stemming from the presence of impairments and disabilities. (World Health Organization, 1980, p. 29). Although presumably not intended, this passage suggests that people are disadvantaged because of their disabilities alone, and that handicaps are caused by impairments and disabilities. As a result, the user of the ICIDH cannot record, let alone measure, the effect that an unaccommodating environment has on people’s lives. The user can record changes in a person’s level of ability, but would have no way of knowing whether that was the result of changes to the person (rehabilitation), or changes to the social and physical environment (accommodation). As far as the ICIDH is concerned, the social and physical world is immutable and benign. The underlying model does not clearly acknowledge that the presence of social barriers and the absence of social facilitators play any sort of role in the creations of the disadvantages that a person with a disability experiences.In 1993, the World Health Organization began the process of revising the ICIDH. Released in 2000, the ICIDH-2 embodies what is now termed the “biopsychosocial” model, a synthesis of the medical and social approaches to disablement. ;
- National Center for Medical Rehabilitation Research (NCMRR) of Bethesda  : The stated mission of the NCMRR, a center within the National Institutes of Health, is to enhance the quality of life of people with disabilities through the development of scientific knowledge. NCMRR developed a model that describes disability and was based both on Nagi’s model and on the I.C.I.D.H. in an attempt to overcome the limits of both, more precisely, the fact of assuming a linear causal relationship among the various consequences of pathologies, and failing to analyze the role of environmental factors in the dynamics of the relationships among the various levels (NCMRR 1993); NCMRR (1993) built on the Nagi model by including the impairment, functional limitation, and disability domains corresponding to the organ, person, and societal levels, but NCMRR added another level or “dimension,” called “societal limitation”. Societal limitations are barriers to full participation in society that result from attitudes, architectural barriers, and social policies. The NCMRR model pulled external barriers out of the environmental domain for special emphasis, highlighting the fact that these barriers could be reduced or eliminated by public policy.
- International Network on Disability Creation Process (INDCP) [Patrick Fougeyrola, INDCP, 1991-96-99] : An explicative model of the causes and consequences of disease, trauma and other disruptions to a person’s integrity and development;
- International Classification of Functioning, Disability and Health (ICF) [WHO, 2001] : The World Health Organization (WHO) authorized the International Classification of Functioning, Disability and Health (ICF) in 2001. The ICF defined disability as a complex interaction between body structures and functions, health issues, and environmental and personal factors which affect the participation of people in activities. The ICF model broadens the health care provider’s focus from the pathological process to the level of health and participation of the person. To the contrary, when viewing a person through a medical model of disablement, disability is viewed as a consequence of dysfunctional health, not a component of health. The ICF provides a tool that measures a person’s functioning and participation within society, regardless of his disability. The ICF provides for a more interacting picture of the person and the contributing factors that influence his daily functioning and participation. It serves to overcome many of the limitations of previous disablement models by examining not only the health condition (wellness, disorder, or disease) but also contextual factors (personal and environmental factors), body structure and function, activities, and participation.
THE CONCEPT OF FONCTIONAL LIMITATION
The concept of functional limitations (FL) has occupied a cardinal role in the field of rehabilitation for many years. Despite the centrality of this concept to the daily work of rehabilitation professionals, it has not been without its share of problems. For example, the very notion of a classification of functional limitations has spawned many, and often, rather diverse efforts by researchers and clinicians (e.g., Crewe & Athelstan, 1981; Marsh, Konar, Langton & LaRue, 1980; Sarno, Sarno & Levita, 1973; Wright, 1980). Furthermore, the ever-evolving conceptualization of the terms of impairment, disability and handicap, and their relationship to functional limitations and functional capacities (i.e., residual functions maintained following a disease or injury) has also thwarted efforts at defining, clarifying and categorizing functional limitations (Granger & Gresham, 1984; Halpern & Fuhrer, 1984; Nagi, 1969, 1976; World Health Organization, 1980). Finally, the various systems developed over the past four decades to assess human functions show a remarkable degree of diversity, and range from those directed at measuring only physical functions to those addressing a wide array of life spheres (i.e., physical, psychological, social, educational, vocational and environmental areas) (Agerholm, 1975; Brown, Gordon & Diller, 1983; Granger & Gresham, 1984; Halpern & Fuhrer, 1984).
The concept “Functional limitation” (FL) may derive from the NAGI, NCMRR, ICIDH, disability models.
According to the ICIDH of the World Health Organization (WHO), a functional limitation is any health problem that prevents a person from completing a range of tasks, whether simple or complex.
SOME DEFINITIONS RELATED TO DISABILITY
Impairment is defined as « any loss or abnormality of psychological, physiological, or anatomical structure or function » (World Health Organization, 1980, p. 47). Impairment reflects disturbances at the body’s organ level (e.g., leg, back, brain). Measures of impairment typically include those concerned with specific restrictions of some physical, mental or emotional capacity (Halpern & Fuhrer, 1984).
Disability is defined as « any restriction or lack of ability to perform an activity in the manner or within the range considered normal for a human being » (WHO, 1980, p. 143). Disability reflects disturbances at the person level. In other words, it relates to deficiencies in normally expected function, performance, or behaviour (e.g., inability to walk, inability to sit for an extended period of time, limited self-awareness, limited ability for acquisition of knowledge). Measures of disability customarily include those addressing restrictions of skills a person manifests when interacting with the environment (e.g., Activities of Daily Living Scales) (Halpern & Fuhrer, 1984).
Learning disability (sometimes called a learning disorder or learning difficulty), is defined as a classification including several disorders in which a person has difficulty learning in a typical manner, usually caused by an unknown factor(s). The unknown factor is the disorder that affects the brain’s ability to receive and process information. This disorder can make it problematic for a person to learn as quickly or in the same way as someone who isn’t affected by a learning disability. Learning disability is not indicative of intelligence level. Rather, people with a learning disability have trouble performing specific types of skills or completing tasks if left to figure things out by themselves or if taught in conventional ways.
A Functional Limitation (FL) is « a consequence of a health problem and represents an inability to meet a standard of an anatomical, physiological, psychological, or mental nature (impairment). This can lead to reduction in behavioural skills or performance of tasks (disability) or deficits in fulfilment of social role (handicap) » (Granger, 1984, p. 16). As such, FL represents a substandard organismic performance (Nagi, 1976), particularly in performing life activities, using skills and fulfilling social roles. FL, then, is the result of an interaction between an impairment and the environment (Granger, 1984; Indices, 1979).
A Functional Capacity (FC) is the « degree of ability to perform a specific role or task which is expected of an individual within a social environment » (Indices, 1979, p. 7). Hence, FC represents the residual physical, cognitive or behavioural capabilities of an individual in his or her task performance and environment negotiation.
Functional Assessment (FA) is « the measurement of purposeful behaviour in interaction with the environment, which is interpreted according to the assessment’s intended uses » (Halpern & Fuhrer, 1984, p. 3). The three primary categories of behaviour include (a) physical, cognitive or emotional capacity; (b) performance of useful skills or tasks; and (c) performance of social roles. Environments in which behaviour is performed include the home, community and workplace (Halpern & Fuhrer, 1984). Thus, while FL and FC address the object or outcome of assessment, FA refers to the actual process of the assessment.
Whereas impairment and disability are terms that pertain to organic and behavioural dysfunctions, respectively, FL and FC imply two additional components, namely, analysis of diagnostic (for impairment) and performance (for disability) indicators, and assessment of abilities and activities (see, for example, Granger, 1984; Halpern & Fuhrer, 1984). Put differently, impairment and disability are general terms that are more concerned with diagnosis and classification of organic conditions and their assumed skill performance. FL and FC, alternatively, are applied terms where specific degrees of limitation or residual capacity are addressed and assessed as they relate to particular life contexts.
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