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Intellectual disability: an approach from the health sciences perspective



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medigraphic Artemisa en línea Intellectual disability: an approach from the health sciences perspective Luis Salvador-Carulla, (1) Carmen Rodríguez-Blázquez, (2) Almudena Martorell. (3) Salvador-Carulla
medigraphic Artemisa en línea Intellectual disability: an approach from the health sciences perspective Luis Salvador-Carulla, (1) Carmen Rodríguez-Blázquez, (2) Almudena Martorell. (3) Salvador-Carulla L, Rodríguez-Blázquez C, Martorell A. Intellectual disability: an approach from the health sciences perspective. Salud Publica Mex 2008;50 suppl 2:S142-S150. Abstract Intellectual disability (ID) is a complex condition that has not aroused very much interest in the health sciences and medical fields. As a result, a large part of the responsibility for caring for individuals with ID has fallen in the areas of education, social services and volunteering. Nevertheless, intellectual disability is a very significant health problem, whether because of its prevalence, the costs to the public health system, the families and society in general or due to related health complications. ID should be a priority area of study and action in the health field. This article reviews the conceptual, diagnostic and etiological problems that affect intellectual disability, as well as factors related with the health of the persons who are affected. In addition, some recommendations are outlined for improving health care for this population group. Key words: intellectual disability; health; conceptual framework Salvador-Carulla L, Rodríguez-Blázquez C, Martorell A. Discapacidad intelectual: un enfoque desde la perspectiva de las ciencias de la salud. Salud Publica Mex 2008;50 supl 2:S142-S150. Resumen La discapacidad intelectual (DI) es una condición compleja que no ha despertado gran interés en el campo médico y en el de las ciencias de la salud. Como consecuencia, gran parte de la responsabilidad del cuidado de los individuos con DI ha recaído en las áreas de la educación, el servicio social y el voluntariado. Sin embargo, la discapacidad intelectual es un problema de salud muy significativo, ya sea por su prevalencia, por los costos para el sistema de salud pública, para las familias y para la sociedad en general o debido a las complicaciones de salud relacionadas con ella. La DI debería ser un área de estudio y de acción prioritaria en el campo de la salud. Este artículo revisa los problemas conceptuales, diagnósticos y etiológicos que afectan a la discapacidad intelectual, así como los factores relacionados con la salud de las personas afectadas. Además se delinean algunas recomendaciones para mejorar el cuidado de la salud en este grupo de población. Palabras clave: discapacidad intelectual; salud; marco conceptual (1) Section Chair of the Psychiatry of Intellectual Disability of the World Psychiatric Association. (2) Centro Nacional de Epidemiología, Instituto de Salud Carlos III, Madrid (Spain). (3) Fundación Carmen Pardo-Valcarce, Madrid (Spain). Accepted on: December 5, 2007 Address reprint requests to: Luis Salvador-Carulla. San Marcos 6, Jerez 11403, España. S142 salud pública de méxico / vol. 50, suplemento 2 de 2008 Intellectual disability: a health sciences approach ARTÍCULO DE REVISIÓN Historically, intellectual disability (ID) has received variable attention in developed countries from charity to the development of specific devices for socialeducational care. ID terminology has varied over time. In the past, terms have been used such as imbecility, mongoloidism, mental deficiency and mental retardation. Since 2004, there has been a broad consensus in favor of the use of the term intellectual disability. Prominent international and national associations have already accepted the denomination of this disorder. Thus, the American Association of Mental Retardation (AAMR) has changed its name to the American Association of Intellectual Disability (AAIDD) 1 and the World Health Organization (WHO) uses this term as a synonym for mental retardation. No other medical illness exists that brings together the specific characteristics and nuances entailed by the concept of ID, although it has received very little attention on the part of health sciences and health services in general. In fact, in many countries, caring for persons with ID has been limited to the area of social and educational services or social welfare. As an indication of such lack of interest, suffice to say that ID is not included in the World Bank and WHO Global Illness Burden. There are diverse reasons for this scarce interest. First, there is no international consensus on the definition of intelligence or on how to quantify it. Second, more epidemiological studies are needed about the effect of early cognitive developmental disorders on public health in order to designate priorities and design effective interventions, especially in undeveloped countries. Third, while for distinct psychiatric disorders from personality disorders to schizophrenia there is an intense debate about classification criteria, in the area of ID the debate almost exclusively focuses on assigning the appropriate name to the concept and on how to evaluate skills and the kind of support needed. Fourth, there is not a sufficient amount of funds designated for ID research since it is not a key issue in national ID programs and the pharmaceutical industry is not interested in ID research. This creates a vicious circle: since there are no resources for conducting research, not enough scientific research is produced about ID for it to be incorporated into mental health policies based on the evidence, or for improving the classification and diagnosis system (for example, the International Classification of Illnesses ICD-10, Statistical Diagnostic Manual DSM- IV) or for devising good practice guidelines or other tools to guide the homogenization of socio-health care. And last, many professionals and families/service users believe that it has more to do with social or educational concepts than with a health condition. 2 One factor that increases the difficulty in understanding the term ID is the conceptual reference framework. It is not a medical disorder, although it has an illness classification code (for example, International Classification of Illnesses, 10th version, ICD-10, 2002), and it is not a mental illness, although it is included in classifications for mental disorders (for example, the DSM-IV-TR, American Psychiatric Association, 2002). In fact, it is a type of syndrome (a metasyndrome) that is similar to the concept of dementia. 2 ID has a prevalence of 1.5% in western countries, although this rate can increase to 4% in less developed nations 3 due to factors such as the presence of neurotoxic agents or nutritional deficiencies during pregnancy. A considerable proportion of persons with ID have plurideficiencies and medical problems. In addition, ID has consequences throughout one s lifetime and entails a significant burden for families and caregivers, demanding a high level of service provisions. ID is the principal cause of socio-health expenses, not only in the mental health sector but also in the medical field, at least in western countries. 4 Due to its importance, it is consequently necessary to deepen the concept of ID from a comprehensive social perspective, without overlooking conceptual, nosological, medical, pharmacological and psychiatric factors. The concept of intellectual disability ID refers to a particular state of intellectual and adaptive functioning, which begins in infancy and in which limitations in intelligence coexist with attenuated cognitive, social and practical skills. The problems and deficits in the subject with ID may have a specific cause, but ID is not synonymous with an etiological factor. The term ID includes, by definition, three essential components: a) intellectual functioning significantly below average with an intelligence quotient (IQ) less than 70 (measured using psychometric tests such as the Wechsler Intelligence Scales for Children-Revised, Stanford- Binet, Kaufman Assessment Battery for Children); b) a marked deficit in the ability of the individual to adapt to the daily demands of their social environment (neither of these factors low intelligence and deficient adaptive conduct is sufficient for establishing an ID diagnosis if they are regarded individually); and c) onset before the age of 18. Slight variations exist in the codification of the severity levels for ID, although the important division is that of mild and moderate (IQ greater than 35-40), severe (IQ to 35-40) and profound (IQ less salud pública de méxico / vol. 50, suplemento 2 de 2008 S143 than 20-25). In spite of the fact that the above divisions are generally agreed upon, the American Association on intellectual and Developmental Disabilities (AAIDD), in their latest definition (2002), 5 moves away from the importance given to date to the measurement of intelligence, which depends more on the evaluator s judgment than on intellectual tests. In addition, for the purpose of using language that is focused more on needs and less on deficits, the AAIDD proposes a new categorization for ID degrees: the need for intermittent, limited, extensive or generalized support. It also needs to be clarified that it is necessary to view functional limitations in relation to the social and cultural context of age and cultural peers and to consider cultural and linguistic diversity, as well as differences in communication and sensorial, motor, and behavioral aspects. The fundamental objective for the evaluation and diagnosis of ID is the development of a profile of types of support necessary to enable the improved functioning of persons with ID. Finally, the subjects abilities and skills that may contribute to such improvement should also be evaluated. 3 Etiopathogenic and diagnostic factors Table I PRINCIPAL CAUSES OF SYNDROMES THAT ACCOMPANY INTELLECTUAL DISABILITY Cause Metabolic disorders: Lipids Mucopolysacaridosis Amino Acids Carbohydrates Purines Genetic disorders: Neurocutaneous Chromosomal alterations: Trisomy Linked with X chromosome Microdelection Mutation External causes: Intrauterine infections Toxic substances Perinatal problems Malnutrition, social or affective deprivation Example Tay-Sachs Disease Hurler Syndrome Phenylketonuria Galactosemy Lesch-Nyhan Syndrome Tuberous Sclerosis Down Syndrome Fragile X Syndrome Prader-Willi Syndrome Smith-Lemli-Opitz Syndrome Rubella, Syphilis Fetal Alcohol Syndrome Anoxia, Prematurity One factor in ID that contributes to conceptual problems is the heterogeneity of the etiological factors, which are summarized in table I. In addition, in 60% of persons diagnosed, the deficit or alteration that causes ID is not known. In many mild ID cases it is difficult to find a specific, underlying medical cause, although signs appear that would suggest that neurological damage or social deprivation (poverty, malnutrition, etc.) are possibilities. In this respect, Zigler 6 proposes subdividing the population of persons with ID into those who have suffered an interruption in the maturation process and those who do not reach the level expected in the population, in spite of having completely developed. The first group includes the majority of non-biological causes, especially social deprivation. The second group includes all of the causes that can be characterized as biological, since they are precisely what make average intellectual functioning impossible. Among the diverse causes of ID, due to its importance it is worth citing genetic anomalies, that make up 30% of the cases; standing out among these, because of their high prevalence, are trisomy 21 or Down syndrome (one in 800 live births) and fragile X syndrome (five out of every births). Determining the causes of ID is essential for intervention since health care expenses would decrease and the response to treatment and the prevention of possible complications would improve. 7 In this respect, in recent years the term behavioral phenotype has been introduced, which is described by Flint and Yule as: a characteristic pattern of motor, cognitive, linguistic, and social abnormalities that is consistently associated with a biological disorder. In some cases, the behavioral phenotype may constitute a psychiatric disorder; in others, behaviors which are not usually regarded as symptoms of psychiatric disorders may occur. 8 Knowledge about the behavioral phenotype helps to plan and organize the care of persons with ID. Although the first behavioral phenotypes were nearly exclusively based on syndromes with genetic origins, today it is possible to talk also about behavioral phenotypes for non-genetic conditions that accompany ID such as fetal alcohol syndrome which are applicable to the set of ID disorders with biological origins. It is necessary to take into account that ID can be confused with other syndromes that begin in infancy or that also involve cognitive or social functioning deficits, such as learning or communication disorders (without a connection to ID), where a developmental alteration is observed in a specific area (reading or expressive S144 salud pública de méxico / vol. 50, suplemento 2 de 2008 Intellectual disability: a health sciences approach ARTÍCULO DE REVISIÓN language, for example) but there is not a generalized affect in intellectual development and adaptive skills. In addition, it is necessary to differentiate ID from generalized development disorders that are characterized by a qualitative developmental affectation in social interaction and verbal and non-verbal social communication skills that may or may not be connected with ID. Furthermore, ID must be distinguished from other syndromes or that are also associated with cognitive dysfunction, such as dementia or cognitive deterioration, but whose diagnosis requires that memory affectation and other cognitive deficits are significantly attenuated in comparison with prior ability levels. Lastly, limited intellectual ability is described by an IQ interval higher than that required for ID (71-84). It is possible to diagnose ID in individuals with IQ scores between 71 and 75 if they have the characteristic deficit in adaptive behavior. In order to differentiate mild ID from limited intellectual ability, careful review of all of the available information is necessary. 9 Health and intellectual disability Medical advances have enabled persons with ID to live longer and have a better quality of life than in the past. Nevertheless, increased life expectancy has resulted in new medical situations (for example, a higher incidence of dementia) that, when added to the comorbility derived from the very causes of ID, require an in-depth study of medical and health factors related with ID. This population has many difficulties in terms of access to community health services. In Europe, an appropriate response to this problem was the initiation of Project Pomona, 10 which has been carried out in European Union countries since The principal objective of this project is to identify the health indicators, based on evidence, that reflect the most important areas for improving the quality of life of and equal access to health care for persons with ID. This process in identifying factors has been conducted with the participation of subjects with ID, their families, professionals and administrators. Project Pomona is based on the principal that health is one of the parameters for quality of life. Individuals with ID are citizens who have an inherent right to equal opportunities in terms of health care and social inclusion. Nevertheless, this is not always carried out in practice and the project, therefore, attempts to identify the factors that explain the health disparities found between persons with ID and the general population. The objective is for patients with ID to be able to make informed decisions about their own health in an autonomous manner. Health indicators identified by Project Pomona include the following: 1. Demographic indicators: prevalence, type of housing, occupation, socio-economic status/income, life expectancy. 2. Health status indicators: epilepsy, buccal health, body mass index, mental health, auditory and mobility skills. 3. Determinants: physical activity, behavioral problems, psychopharmacological consumption. 4. Health system: hospitalization and contact with health professionals, health check-ups, health promotion, specific training of medical professionals. Health problems for persons with ID In recent years, it has been shown that subjects with ID not only have more health needs than general population, but also that these needs are barely covered and, when they are, the health care received is usually not adequate. Various explanations have been formulated with respect to this lack of care, 11 such as: lack of knowledge on the part of primary care doctors about common medical problems in the ID population; communication problems when interviewing a patient with ID, especially for those with severe or profound disabilities; and the existing gap in assistance between social services and health services, since nobody in particular is responsible for these individuals. Kerr and colleagues 12 state that this population experiences the same health problems as the population without disabilities; but some are more frequent and others are more specifically related to certain syndromes that accompany ID, including: 1. Cancer: Types of cancer most often found in individuals with ID differ with respect to individuals without this disability; there is a higher incidence of gastrointestinal cancers (esophagus, stomach, gall bladder) two times higher in patients with ID and, to a lesser extent, malignancies of the lung, prostate, breast and cervix Coronary disease: Coronary diseases are the second cause of death in persons with ID. 14 These individuals are more prone to developing hypertension and obesity and exercise is non-existent; all vulnerability factors for cardiac ischemia. Persons with Down syndrome have a greater risk of congenital cardiac disease. 3. Buccodental problems: Subjects with ID are more prone to developing cavities, tooth loss and gum disease and experience a greater number of dental salud pública de méxico / vol. 50, suplemento 2 de 2008 S145 extractions. This may be due to dietary deficiency, poor dental hygiene or the inaccessibility of buccal hygiene campaigns to this population; persons with ID rarely visit the dentist. Individuals with Down syndrome possess a higher rate of buccodental problems, such as mouth deformations and gum problems Diabetes: Persons with ID have a higher rate of diabetes in comparison with the general population. This may be due to the high rate of obesity, poor diets or sedentary lifestyles Epilepsy: While epilepsy affects 1% of the population, it affects 33% of subjects with ID, and the percentage rises with the increased severity of ID Gastrointestinal problems: Many persons with ID have high levels of Helicobacter pylori, especially those who have lived in institutions or shared residences. 18 Gastroesophageal Reflux Disease can affect as many as half of the subjects with ID. 19 This anomaly has been linked with fragile X syndrome and may be one of the causes for the enormous rates in cancer of the esophagus. In addition, persons with Down syndrome are more prone to colic. 7. Respiratory diseases: This is the leading cause of death in patients with ID, 20 since they are more vulnerable to respiratory tract infections due to aspiration or reflux, if they have deglutition difficulties. Persons with Down syndrome are at particular risk since they are prone to suffering pulmonary abnormalities, they have a deficient immune system and are likely to breathe through the mouth. 21 Pulmonary complications have also been reported in subjects with tuberous sclerosis. 8. Sensory problems: Auditory and visual problems are very common in these patients. It is calculated that 40% have vision problems, and the percentage is similar for auditory problems. In addition, subjects with ID are more pron
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