Health Research The Health Status and Needs of Individuals with Mental Retardation* Download print version (Adobe PDF file, 490K) of this research paper Sarah M. Horwitz, Ph.D.; Bonnie D. Kerker, M.P.H.; Pamela L. Owens, Ph.D.; Edward Zigler, Ph.D. Department of Epidemiology and Public Health, Yale University School of Medicine; Department of Psychology, Yale University New Haven, Connecticut September 15, 2000 (Revised December 18, 2000) * In 2004, Special Olympics updated its official terminology from "mental retardation" to "intellectual disabilities" - previously the term "mental retardation" was used throughout the Special Olympics movement because of its specific meaning in clinical and academic settings. Other terminology - including cognitive delay, intellectual disabilities, intellectual handicaps, learning disability, mental disabilities and mental handicaps - is used around the world. Please see the Special Olympics Language Guide for more information. Table of Contents Chapter 1: Introduction Purpose 1 Definition of Mental Retardation 5 Prevalence of Mental Retardation 12 References 19     Chapter 2: Physical Health Conditions Contributing to Morbidity and Mortality of Individuals with Mental Retardation Introduction 29 Mortality and Morbidity 30 Summary and Implications 55 References 57     Chapter 3: Mental Health Disorders Among Individuals with Mental Retardation Introduction 71 Diagnosis of Mental Health Disorders among Individuals with MR 72 Rationale for Mental Health Morbidity 75 Prevalence of Mental Health Morbidity 76 Specific Conditions 80 Summary and Implications 92 References 94     Chapter 4: Ocular Impairments Among Individuals with Mental Retardation Introduction 106 Prevalence 106 Ocular Conditions Among Specific Populations 109 Rationale for Increased Prevalence 111 Summary and Implications 112 References 114     Chapter 5: Dental Health Among Individuals with Mental Retardation Introduction 119 Prevalence 120 Dental Conditions Among Specific Populations 123 Rationale for Increased Prevalence 125 Summary and Implications 126 References 128     Chapter 6: Health Services Use for Individuals with Mental Retardation And Summary Recommendations Introduction 135 Health Care Service Utilization for Individuals with MR 137 Barriers to Care 141 Efforts to Address Unmet Need 153 Summary and Implications 155 Summary Recommendations 157 References 160   CHAPTER 1 - Introduction Purpose In recognition of the need to improve the quality of life of individuals with mental retardation (MR), Special Olympics Inc. (SOI) commissioned this report to examine the health needs of children and adults with MR. The purpose of this report is three-fold: 1) to identify the current health status and needs of individuals with MR, 2) to identify services gaps in supporting these needs and 3) to propose specific recommendations to address the unmet health care needs of individuals with MR. Early in the 20th century, individuals with MR were generally isolated, rather than encouraged to lead fulfilling and healthy lives (David, 1970; Rix, 1986, Campbell, 1999). The last 40 years, however, have seen dramatic changes in sentiments regarding those with MR, resulting in a turn in public policy towards an emphasis on normalization and inclusion (Rowitz, 1992; Kauffman and Hallahan, 1995; Parmenter, 1999). Other developed countries, such as Canada, the United Kingdom (U.K.), the Scandinavian countries and Australia, have seen similar movements (Malin, 1981; Rowitz, 1990; Parmenter, 1999). As a result of these changes in developed countries, much debate and research has focused on the prevention of MR, deinstitutionalization, and the education and employment of individuals with MR (Tizard, 1971; Clarke, 1991; Anderson et al., 1998). In the U.S., these themes are reflected in court cases, legislative actions and federal initiatives, including Wyatt v. Stickney (1972), Public Law 94-142 and its successor, the Individuals with Disabilities Education Act (IDEA), the Americans with Disabilities Act (1990) and reports by the President's Committee on Mental Retardation (Anderson et al., 1998). Globally, a variety of international organizations, such as the International Association of Scientific Studies on Intellectual Disability, have been developed to support and study both the prevention of MR and the public education concerning individuals with MR (Clarke, 1991). The health status and health service needs of individuals with MR, however, have received little attention over the past four decades. This lack of attention to health status is surprising, particularly in light of the tremendous gains in life expectancy which have resulted from medical and public health advances. The life expectancy of individuals in the U.S. increased 27.26 years between 1900 and 1990 (NCHS, 1999), and in 1997, the average life expectancy was 76.5 years (Anderson, 1999). Similarly, the life expectancy for individuals in Western Europe increased in the past century, resulting in a current average life expectancy of 74.0 years (Population Division, 1998). Increased longevity is evident not only in the general population, but also among individuals with MR (Rowitz, 1992; Janicki and Breitenbach, 2000). Currently, the average life expectancy of older adults with MR is 66.1 years, but younger adults with MR are expected to live as long as their peers without MR (Janicki et al., 1999). With improved assistive technology and effective public health programs that control most infectious diseases, not only are individuals with mild MR living longer but some individuals with more severe MR also have increased life expectancies (Eyman et al., 1988). As a result, these individuals have recently been faced with the same chronic diseases, including cardiovascular disease, cancer and diabetes, which confront the general adult population (Moss and Turner, 1995 in Barr et al., 1999). Although effective health prevention strategies and treatments exist for many diseases (Bunker et al., 1995; U.S. Preventive Services Task Force, 1996), not everyone benefits equally from these medical interventions. The poor, minorities and the socially disadvantaged disproportionately have poor health outcomes and lack access to adequate health care services (Hertzman et al, 1994). Individuals with MR are particularly vulnerable to having unmet health care needs, as they are faced with many challenges in understanding and maintaining their health (President's Committee on Mental Retardation, 1999). Individuals with MR may have difficulties understanding the effects of behavior on health, the risks and benefits of medical treatment, and the process of accessing appropriate and necessary health services (Barr et al, 1999; President's Committee on Mental Retardation, 1999). In addition, when health care services are utilized by this population, health providers may have difficulties recognizing and treating various diseases, obtaining accurate medical histories and communicating with patients who have cognitive and language disabilities (Schor et al., 1981; Minihan and Dean, 1990; Lennox et al., 1997) The lack of access to appropriate health care services also may be a relatively new problem for individuals with MR, resulting, at least in part, from the deinstitutionalization of the 1970s and 1980s. Between 1967 and 1997, as individuals with MR were mainstreamed into the community, there was a 71% reduction in the number of individuals in state MR/developmental disability facilities (Anderson et al., 1998). Trends of declining populations in MR facilities also are evident in other developed countries, such as Great Britain, where there was a 36% reduction in the number of individuals in long-stay hospitals between 1980 and 1990 (Hart, 1998). As a result of deinstitutionalization, all but the most severely disabled individuals with MR are expected to function in the community environment. Many of these individuals can and do achieve levels of functioning that were not previously thought possible (President's Committee on Mental Retardation, 1999). Not all, however, have their health care needs adequately addressed in the community, due to a limited availability of community resources and a lack of access to both knowledgeable care providers and a continuity of care (Savino et al., 1973; Saenger et al., 1979; Newacheck et al., 2000). In addition, the recent increase in managed care, and its emphasis on cost-containment, may exaggerate the impact that poor access to quality medical care has on this population (Kastner, 1991; Department of Health, 1995 in Jones and Kerr, 1997, President's Committee on Mental Retardation, 1999). As a result, unmet health care needs may be an unintended consequence of deinstitutionalization. Although controversy remains regarding the quality of care received in institutions (Landesman and Butterfield, 1987; Lowe et al., 1995), individuals in residential centers were at least likely to have a usual source of care and be seen by providers experienced in the treatment of individuals with MR (Durkin, 1996). Consequently, to develop a coherent set of recommendations for the improvement of the health of individuals with MR, a thorough review of the literature on the current health status of those with MR was commissioned by SOI. In preparation for this report, several steps were taken to ensure a thorough review of academic and public policy documents. Researchers searched Medline and PsycInfo for peer-reviewed articles on the physical, mental, dental and ocular health of people with MR, as well as the availability and accessibility of health care services for these individuals. Many of these studies utilized administrative data accessed from service delivery databases. In addition, publications and reports were obtained from national and international organizations focusing on MR, including the American Association for Mental Retardation (AAMR), The Arc of the United States, and the International Association for the Scientific Study of the Intellectual Disabilities (IASSID). Based on a search of GPO Access and the Internet, government documents that relate to the health and health service use of individuals with MR also were obtained. Further, individuals from several federal agencies (including the Centers for Disease Control and Prevention, the National Council on Disability, the President's Committee on Mental Retardation, the U.S. Bureau of Census and the U.S. Department of Health and Human Services) were contacted and interviewed. Although numerous articles exist regarding the health status and needs of individuals with MR, not all are scientificially rigorous or pertinent to this manuscript. Therefore, while approximately 1,100 articles were considered, only 548 were admitted into this review. Individuals from academic institutions and those involved in programs for individuals with MR through SOI, including Drs. Paul Berman, Sandra Block, Steve Corbin, Matthew Janicki, Steven P. Perlman, and H. Barry Waldman, also provided additional information. National U.S. datasets, including the National Health Interview Survey (NHIS), the National Health Expenditure Survey and the Survey of Income and Program Participation, also were reviewed to determine the availability of data related to individuals with MR. Following a review of the definition and prevalence of MR, this report examines the physical, ocular, mental and dental health needs of individuals with MR. Next, the health care services available and accessible to this population are discussed. The report concludes with a list of recommendations, proposed to improve the health of individuals with MR. Definition of Mental Retardation - Introduction Valid measurement is the cornerstone of reliable epidemiological studies. Inappropriate measurement can result in a misclassification of either exposures or outcomes (in the case of this review, the classification of individuals with or without MR), which may lead to inconsistent or biased results (Armstrong et al., 1992; Kelsey et al., 1996; Rothman and Greenland, 1998). To ensure the correct classification of individuals into the categories of interest, definitions should be precisely specified from the outset of any study (Rothman, 1986). This is particularly important when examining social, psychological or cognitive impairments, such as MR, because often no objective biological measurement of these conditions exists (Kelsey et al., 1996). An accurate and consistent definition of mental retardation is critical because of its impact on the prevalence, or count, of those with MR. However, despite the importance of consistency, MR is not always defined in the same way across research studies or service agencies, even within the same state (Koller et al., 1984; Borthwick-Duffy et al., 1994). While some definitions rely on IQ scores alone to classify individuals with MR, some only use adaptive behaviors for classification, and others include both IQ scores and measures of adaptive skills (Whitman et al., 1990; Borthwick-Duffy et al., 1994). In addition, many studies are based on broad categories of either severity (using labels such as mild, moderate, severe and profound MR) or etiology (utilizing the terms cultural/familial and organic MR). Definition of Mental Retardation: The most commonly cited definition of MR comes from the AAMR. Most recently (1992), the AAMR has defined MR as the onset of significant limitations in both general intellectual and adaptive functioning during the developmental period (18 years and under). Intellectual limitations refer to an Intelligence Quotient (IQ) which falls two standard deviations below the population mean of 100 (<70), and adaptive functioning limitations refer to impairments in at least two out of ten skill areas (AAMR, 2000). MR is also defined in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) by the American Psychiatric Association (APA). Similar to the AAMR definition, the DSM-IV has three diagnostic criteria for MR, including sub-average intellectual functioning (IQ < 70), impairments in adaptive functioning and onset before age 18 (APA, 1994). Although the core criteria for MR are similar between the AAMR and the DSM-IV definitions, there are important differences between the two. First, while the DSM-IV definition of MR has a strict IQ cutoff of 70, the 1992 AAMR definition indicates that if an individual presents with other signs of MR, the IQ cutoff may be raised to 75 (Schalock et al., 1994; Reiss, 1994). Second, although both definitions include a sub-classification system, the bases of the two sub-classification systems differ. The AAMR definition includes a scale measuring the extent of support needed to function in the environment, focusing on an individual's strengths, support systems, capabilities and interaction with the environment (Schalock et al., 1994; King et al., 1997). In contrast, the DSM-IV definition specifies the degrees of MR severity based on the level of IQ (mild=50-55 to 70, moderate=34-40 to 50-55, severe=20-25 to 35-40 and profound <20-25) (APA, 1994). Further, although not formally part of the definition of MR, the APA includes MR in the DSM-IV, thereby classifying MR as a mental disorder. The AAMR, however, explicitly states that MR is neither a medical nor a mental disorder (AAMR, 2000). Considerable controversy exists over the use of the 1992 AAMR definition, however. While the definition was intended to broaden the definition of MR so that more individuals would be eligible for services (Reiss, 1994; MacMillan et al., 1995), several researchers believe that the 1992 definition compromises the conceptual and psychometric integrity of the 1983 definition of MR (MacMillan et al., 1995). Prior to 1992, for example, the AAMR definition focused on deficits at each developmental stage, using a severity scale (similar to that used by the APA) to emphasize IQ scores and expected age-appropriate behaviors (AAMD, 1983). In 1992, however, the AAMR increased the possible upper IQ score to 75, set general adaptive behaviors as a criterion and developed a sub-classification system based on levels of needed supports (MacMillan et al., 1993). Critics of the new definition believe that setting the IQ score limit to 75 may result in a classification of MR for individuals who have skills similar to their peers without MR, and may lead to an over-classification of minorities as having MR. Further, reliance on IQ has been criticized because of the cultural biases inherent in this measure (Hobbs, 1975; Zigler et al., 1984). Additional concern revolves around the measurement of adaptive behaviors and needed supports, which are thought to be poorly defined and to ignore developmental factors, thereby increasing the potential for misclassification. Consequently, some authors believe that a sub-classification system of MR should rely on etiology rather than poorly measured levels of supports (MacMillan et al., 1993). The definitions of MR discussed thus far, however, ignore etiology. In contrast, Zigler and colleagues (1967; 1984; 1986; 1987a; 1991) argue that an appropriate classification of MR employs both IQ score and etiology of the retardation. Consequently, they suggest categorizing MR into cultural/familial and organic groups, based on the presence or absence of a known organic etiology. This two-group approach is one of the most well documented distinctions in the mental retardation literature over the last century. Cultural/familial MR refers to individuals with IQs of 50-70, who do not have any identifiable physiological or genetic deficit. Although individuals with cultural/familial MR have lower intelligence than individuals without MR, the stages of cognitive development do not vary between these two groups. Those with cultural/familial MR, however, cognitively develop at a slower rate and do not reach the same cognitive levels as the general population. Consequently, individuals with the same mental age (or cognitive ability), regardless of chronological age, should perform similarly on cognitive-linguistic tasks. Emotional and motivational factors, however, influence the performance of individuals, and may account for certain behavioral differences between those of the same mental age (Zigler, 1967; Zigler et al., 1984; Zigler and Hodapp, 1986; Zigler and Hodapp, 1991). In contrast, organic MR is attributable to an identifiable physiological deficit. Individuals in this group typically have IQ scores below 50, although individuals with IQ scores between 50 and 70 also can be classified as having organic MR. The cognitive development of individuals in this group is generally not thought to be comparable to those either without MR or with cultural/familial MR. The behavior of individuals in this group, then, is primarily the result of their physiological deficit (Zigler, 1967; Zigler et al., 1984; Zigler and Hodapp, 1986; Zigler and Hodapp, 1991). Some researchers, in fact, believe that all individuals with MR should be classified in the organic group. As science advances, they argue, physiological deficits will be discovered even among those with no present known organic etiology (Knobloch and Pasamanick, 1961 in Zigler and Hodapp, 1986; Richardson, 1981 in Zigler and Hodapp, 1986). Even the two-group approach, however, may be too broad a classification system to adequately account for the heterogeneity of each group. While the cultural/familial group is thought to have at least 3 different subtypes (Zigler and Hodapp, 1986), there are hundreds of identified etiologies of organic MR (Lubs and Maes, 1977; Grossman, 1983). It is inaccurate, then, to view individuals with MR as fitting into one of two homogenous classes (Burack, 1990), particularly because many experts in the area embrace the theory of polygenic inheritance (for a description of the theory, see Zigler and Hodapp, 1986). Although these different definitions of MR do overlap, and are therefore somewhat comparable, multiple classification systems can make comparisons across studies difficult. In addition, the consistency of MR classification has been further complicated by the use of imprecise labeling. In the U.S., for example, many individuals with mild MR have adopted the label "learning disabled," in order to avoid the stigma associated with "mental retardation" (Palfrey, 1994). The label "learning disabled," however, technically refers to individuals of normal intelligence who are not performing at their maximum ability level (AAMD, 1983). Moreover, in England, the term "learning disabled" is used to identify individuals with mental handicaps (Bhrolchain, 1989). This term, then, has become non-specific and includes individuals with a variety of conditions, including those both with and without MR. This type of imprecise labeling can be problematic, because it can lead to difficulties in conducting needs assessments and allocating services, as well as interpreting studies that use this classification. Non-Categorical Classification of Mental Retardation In addition to being defined inconsistently, MR is often grouped together with other conditions. For example, mental retardation is one of many conditions included in non-categorical classifications, such as "disability," which encompass conditions and diseases of different etiologies. In general, this approach has been adopted because it focuses on the similar medical, behavioral and cognitive problems found across illnesses, classifying individuals together based on functioning, rather than diagnosis. In contrast, the categorical approach uses diagnostic labels that do not convey the variability of morbidity within specific diseases (Stein et al., 1993; Stein and Silver, 1999). Eligibility for Social Security Income (SSI), for instance, was previously based on categorical diagnoses. As a result, SSI was denied to those who did not meet severity criteria with a single diagnosis, ignoring the cumulative functional effects of many conditions (Stein et al., 1993). Thus, the non-categorical approach is particularly beneficial for individuals with comorbid conditions, because it increases their likelihood to be eligible for a range of services. Consequently, the non-categorical approach is widely used in legislative initiatives, such as recent education- and employment-related amendments (Stein et al., 1993), and in policy initiatives put forth by agencies such as the National Policy Center for Children with Special Health Care Needs (Ireys et al., 1999). Nevertheless, there are problems associated with the non-categorical approach. When different conditions are grouped together, it is difficult to determine the specific medical and social needs of an individual with a certain diagnosis. Disability, for example, is defined broadly to include several conditions, including MR, developmental disabilities, serious emotional disturbances, ongoing orthopedic disorders, genetic disabilities and chronic illnesses (Ireys et al., 1999). Since the needs associated with these different conditions vary greatly, using this term to represent any one of these groups gives very little information about the needs of an individual with a specific condition. Summary and Implications Because the definitions of MR used across research efforts vary, this report indicates the definition employed when describing study results. Although some research efforts focus on conditions such as Cerebral Palsy and Autism, these studies are not included in this review, since individuals with these conditions do not uniformly have MR. Data on individuals with Down Syndrome (the one condition for which MR is a criterion) however, are presented. Further, although individuals with MR are included within non-categorical classifications, such as developmental disabilities, utilizing these terms in research makes it difficult to conclude anything specific about MR. Thus, in this report, efforts were made to avoid studies employing non-categorical definitions. Prevalence of Mental Retardation Introduction As mentioned above, prevalence data are crucial to the allocation of funding and the development of services, as well as to the comparison of findings between different research efforts. The prevalence of mental retardation is affected by many factors, including the definition of MR, the population studied and advances in medical technology. As discussed in the previous section, the definition of MR is an integral part of the determination of MR prevalence in the population. In addition, the population studied influences the prevalence found and indicates how generalizable that count may be. Most research uses either population-based or service use-based (administrative) data. While many European countries maintain registries of individuals with MR (making population-based studies common in those countries), no such registry or comprehensive national survey exists in the U.S. One national survey of the U.S. population, the NHIS, did have one question regarding MR, but because of the low prevalence found in 1981, the question was dropped in 1988 (Boyle et al., 1994). In addition, in 1994, a supplement to the NHIS (NHIS-D) was employed to collect population-based data regarding disabilities. The definition of MR used in the NHIS-D, however, was not consistent with either the AAMR or the APA definition; rather, the NHIS-D classification focused on previously diagnosed MR, conditions frequently associated with MR, and functional limitations in learning. Further, although MR involves disabilities of development, individuals with MR did not necessarily meet the criteria (three or more functional limitations) to be classified with a developmental disability, as defined by Public Law 98-527, in the NHIS-D (Research and Training Center on Community Living and Institute on Community Integration, 2000). Since 1990, the Survey of Income and Program Participation (SIPP), another U.S. population-based survey, has documented MR among those households randomly selected for participation. It does not, however, make a specific effort to sample households of individuals with MR or other disorders. As a result, given the low probability of identifying individuals with MR in a randomly selected population, the SIPP cannot be considered a comprehensive account of those with MR (U.S. Bureau of the Census, 1999). In addition, both the NHIS and the SIPP underestimate the prevalence of disabilities among children and adults, because individuals living in institutions or group homes are excluded from the surveys (U.S. Bureau of the Census, 1999). In contrast to many European studies, then, most research efforts in the U.S. do not use population-based samples; rather, they rely on the number of individuals who utilize special services to estimate the prevalence of MR in the overall population. Advances in medical technology have had a great impact on the prevalence of MR as well. Throughout the century, medicine's ability to treat the comorbid conditions of individuals with MR, and thus increase their survival time, has improved (Primrose 1984; Whitman et al., 1990). For example, individuals with Down Syndrome tend to suffer from thyroid and heart conditions, which can be better detected and treated today than in the past (U.S. Preventive Services Task Force, 1996; Saenz, 1999; Singer et al., 1995). Therefore, the increased life expectancy of these individuals results in a higher prevalence at any one point in time. Further, several factors potentially affect the number of individuals who are actually born with MR. The rise in prenatal care, increased genetic screening and improvements in neonatal testing, for example, tend to increase the likelihood that children are born healthy. In contrast, other factors, such as increased prenatal substance use, tend to counter-act these effects and increase the prevalence of MR (Grossman et al., 2000). In sum, it is difficult to predict how the synergy of these factors affects the ultimate prevalence of MR. U.S. Prevalence of Mental Retardation It is estimated that as many as 2.0-7.5 million Americans of all ages may have MR, and that 1 in 10 families are directly affected by mental retardation (President's Commission on Mental Retardation, 1997; Grossman et al., 2000). Many reports have suggested that the population prevalence of MR in the U.S. is as high as 3.0% (Tarjan et al., 1973; Zigler and Hodapp, 1986; President's Commission on Mental Retardation, 1997). A U.S. study using administrative data, however, found the prevalence among children to range from 0.3% to 3.1% in different regions of the country, with a national average of 1.1% (King et al., 1997). Similarly, the Metropolitan Atlanta Developmental Disabilities Surveillance Program, a population-based study which only used IQ score as the criterion for MR, found an overall prevalence of 0.9% among 3-10 year-old children (Boyle et al., 1996). Further, although the NHIS-D used its own definition of MR, it reported that .78% of the population had MR, with a prevalence of .45% for children 0-5 years, 2.0% for children 6-17 years, and .52% for individuals 18 years or older (Research and Training Center on Community Living and Institute on Community Integration, 2000). Further, because teachers are often the first to notice mild developmental problems, most identified mild MR is initially detected during school years. The Atlanta population-based study, for example, indicated that while the prevalence of mild or moderate MR was only 0.5% for children 3-4 years of age, the prevalence rose to 1.2%, when older, school-aged children were studied (Boyle et al., 1996). It has been suggested, however, that only 50% of children with MR are identified at a young age because the failure to adapt normally and grow intellectually may not become apparent until later in life. Early identification may be further hampered by the fact that most pediatricians do not generally use standardized instruments to detect developmental delays (Grossman et al., 2000). In addition, because of their high level of functioning, those with mild MR are often unknown to special services once they leave school, and so, as adults, these individuals may not be counted as having MR in studies using administrative data. Moreover, many diagnosed children do not meet criteria when tested later in life. This suggests that either childhood or adult diagnoses are not adequately evaluating adaptive functioning (Forness, 1972 in King et al., 1997), or that IQ scores and functioning may vary over time (Zigler et al., 1984; Zigler and Hodapp, 1986; Loveland and Kelley, 1988 and Dykens et al., 1994 in King et al., 1997). The majority of individuals with MR have historically been classified as having mild, cultural/familial MR. In the Atlanta population-based study 0.84% of 10 year-olds had IQs between 50 and 70 (mild MR), and 0.36% had IQs less than 50 (moderate to profound MR) (Yeargin-Allsopp et al., 1997). In addition, Boyle et al. (1996) reported that two-thirds of the children with MR in this study were classified as mild. Further, the prevalence and type of MR found in this study varied with race and gender, with Black males having percentages of mild, moderate and severe MR 3.1 times as high as those for White females. Percentages of profound MR (most likely organic), however, did not vary by race in this study (Boyle et al., 1996). Part of the variation in the U.S. reported prevalence of MR is clearly due to differences between research efforts. For example, researchers making extrapolations based on birth estimates may report a higher prevalence than the number of cases counted in studies using either population-based or administrative data (Tarjan et al., 1973). The results of these latter studies, however, consistently indicate a prevalence of 1.0%. International Prevalence of Mental Retardation In other developed countries, the prevalence of mild MR appears to be lower than it is in the U.S. Percentages of MR or mental handicap in Sweden, for instance, have been estimated to be between 0.3% and 0.7% (Grunewald, 1979; Golding, 1982; Halldin, 1984, Zigler and Hodapp, 1986). Interestingly, although the prevalence of mild MR has been found to be lower in Sweden than in the U.S., the two countries have reported comparable percentages of severe MR (Zigler and Hodapp, 1986). Sweden's low prevalence of mild MR may seem surprising, given that at least some of the Swedish studies use a higher IQ cutoff (<80) to define this condition. However, Sweden has few psychologists, and testing is not as widespread there as it is in the U.S. (Zigler et al., 1984). Additionally, Swedish prevalence estimates of MR are based on the subjective opinions of teachers and clinicians, who are reluctant to label mildly cognitively impaired children (Zigler, 1987b). Further, since Sweden keeps a registry of individuals with MR, many Swedish studies are population-based, which may lead to a more accurate population prevalence than that estimated in the U.S. In addition, Sweden is a welfare state, and has many programs available for those with mild MR. As a result, many of these individuals are cared for in the community, and may never even be thought of as having MR until their IQs (at least males) are formally tested for entry into military service (Zigler et al., 1984; Zigler and Hodapp, 1986; Zigler, 1987b). When estimates from the community are combined with estimates from armed forces testing, the prevalence estimates for MR increase to 2.21%, similar to that found in other countries (Zigler, 1987b). Other developed countries also have registries of mental retardation, which makes population-based studies more feasible than in the U.S. The overall prevalence of moderate and severe MR, arrested development or severe abnormality among children and adults in England has been found to range between 0.3% and 0.5 % (Wing, 1971; Holt et al., 1973; Elliot et al., 1981; Goh et al., 1994). A study using a surveillance registry in British Columbia found the overall MR prevalence rate to be similar (0.4%), with 0.1% mild, 0.1% moderate, 0.05% severe, 0.04% profound and 0.01% unspecified MR (Herbst and Baird, 1983). In Ireland, using an IQ cutoff of 50 (severe MR), the rate of MR among adults 20-29 was found to range from 0.4 to 0.6% (Mallon et al., 1991). In less developed countries, percentages of MR are generally found to be higher, from 1.6%-3.0% (Islam et al., 1993). However, several recent studies have found the prevalence of MR to be quite low. For example, in The People's Republic of China, the use of intelligence tests in several districts found a prevalence that ranged between 0.4% and 0.7% (Kuo-Tai, 1988). Similarly, a study in Cape Town, South Africa, using administrative data, found the prevalence of severe MR to be 0.3% (Finedlander et al., 1982), and a population-based study of prevalence in Bangladesh found a rate of 0.6% for severe MR and 1.4% for mild MR (Islam et al., 1993). Further, a study that went door-to-door in India, using the Binet-Simon scale to define MR as an IQ<80, has indicated a prevalence rate of 0.4% in the general population and 1.0% among children (Satapathy et al., 1985). Summary and Implications Most prevalence studies, then, utilize IQ alone to define MR. In the U.S., while the range of MR prevalence has been reported to be between 0.3% and 3.0%, most studies using administrative or population-based data have found a prevalence of 1.0%. In contrast, international studies, using population-based registries and somewhat different definitions of MR, report the prevalence to be less than 1.0%. The U.S. prevalence of severe MR, however, is comparable to that of other countries; in fact, some studies have found lower percentages of severe MR in the U.S. than in other countries. Since most mild or moderate MR is identified among school children in the U.S., the discrepancy in the prevalence of those conditions may due to international differences in school-based testing and services requirements (Palfrey, 1994), as well as mainstreaming practices. Further, the low prevalence of MR in some countries may be due to socio-cultural factors. In China, for example, there is a one child per family policy (Kane and Choi, 1999) and a strong preference for terminating pregnancies with genetic abnormalities (Mao and Wertz, 1997), both of which may affect the number of children born with MR. These comparisons indicate that the international discrepancies in prevalence may, in part, be due to the different populations, definitions of MR, and methods of identification used in research studies. Moreover, cultural and political differences among countries may influence both the number of individuals with MR and the numbers that are counted in research studies. Despite these discrepancies, however, individuals with MR are present in all countries, and their needs, including their health needs, merit attention. References 1. American Association on Mental Deficiency (AAMD). Classification in Mental Retardation. Washington, DC: American Association on Mental Deficiency, 1983. 2. American Association on Mental Retardation (AAMR), April 20, 2000. Available at: http://www.AAMR.org. May, 2000. 3. American Psychiatric Association (APA). Diagnostic and Statistical Manual of Mental Disorders, Fourth Addition (DSM-IV). Washington DC: American Psychiatric Assocition. 1994. 4. 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Understanding Mental Retardation. 1986. 99. Zigler E. The Definition and Classification of Mental Retardation. Upsala J Med Sci. 1987a;Suppl.:1-10. 100.Zigler E. Concluding Remarks to Section II. Upsala J Med Sci Supp. 1987b;44:38-40. 101.Zigler E, Hodapp R. Behavioral functioning in individuals with mental retardation. Ann Rev Psychol. 1991;42:29-50. CHAPTER 2 - PHYSICAL HEALTH CONDITIONS CONTRIBUTING TO THE MORBIDITY AND MORTALITY OF INDIVIDUALS WITH MENTAL RETARDATION Introduction For the purpose of this report, physical health conditions refer to chronic conditions that are common causes of death (such as cardiovascular diseases, cancer, diabetes, lung diseases, and unintentional injuries), risk conditions related to these chronic diseases, and childhood conditions and prevention measures that influence the long-term health and functioning of individuals (such as otitis media, pediatric asthma, child maltreatment and immunizations). Other physical health conditions, such as ocular and oral health conditions, are not included in this definition, and will be discussed in separate chapters. Lacking large population-based studies, evidence documenting the prevalence of these physical health conditions among individuals with MR comes primarily from small community registries or administrative data from outpatient clinics or residential facilities. Since many individuals with MR do not receive services on a regular basis (Howells, 1986; Singer et al., 1986), however, studies using outpatient samples may underreport the prevalence of health conditions that do not always prompt medical interventions. Conversely, prevalence estimates from institutions may overreport the prevalence of certain health conditions, because those in hospitals or long-term residential settings are generally the most severely physically impaired and are likely to be monitored at regular intervals (Eyman et al., 1986). Prevalence estimates are also affected by the identification of symptoms, either by the individuals with MR or by the caregiver. Often limited in communication skills, individuals with MR rely on caregivers to identify symptoms and report them to providers. Providers, then, must detect clinical manifestations of disease among individuals who lack communication skills to provide descriptions of symptoms. Consequently, syndromes based largely on reported symptoms rather than physical signs or specific routinely administered tests may also be underidentified. Mortality and Morbidity Despite overall gains in life expectancy, gaps still exist between individuals with MR and individuals in the general population. In Western Europe and the United States, the overall life expectancy at birth is 74.0 to 76.5 years and life expectancy at 65 years is 81.7 to 82.7 years (Hoyert et al., 1997; WHO, 1997). In contrast, individuals with mild or moderate MR have an average life expectancy at 45 of 66.1 years, while those with severe MR have an average life expectancy at 45 of 53.6 years. Thus, the life expectancy of individuals with MR decreases with increased severity of MR and increased severity of physical impairments (Janicki et al., 1999; Eyman et al., 1990; O'Brien et al., 1991; Eyman et al., 1993), suggesting that those with mild or moderate MR have different health trajectories than those with severe or profound MR. Further, life expectancy may be related to place of residence, although the results of the research are inconsistent. Hayden (1998) points out that some researchers have documented higher mortality rates among individuals with MR in institutions compared with those in the community, while others have suggested that individuals in the community have higher mortality rates (Strauss et al., 1998). Living longer than individuals with severe MR, those with mild or moderate MR are more likely to have age-related health conditions similar to the general population. With a few exceptions, the prevalence of physical health problems (including cardiovascular disease, cancer, cerebrovascular disease, lung conditions and diabetes) of individuals with MR is similar to that of the general population. This chapter will focus on the health conditions of adults and children with MR and specific health problems prevalent in individuals with Down Syndrome. The health problems selected for review were based on the leading causes of death in the U.S. population and the health priorities of Healthy People 2000 and Healthy People 2010 (US DHHS 1990, US DHHS 2000a). Adult Health Conditions According to the National Center for Health Statistics (NCHS), the most common causes of death in the United States include cardiovascular diseases, malignant neoplasms or cancer, cerebrovascular diseases, lung diseases, diabetes and unintentional injuries (Hoyert et al., 1999). Not surprisingly, the U.S. has made the prevention and treatment of these conditions a priority in Healthy People 2000 and Healthy People 2010 (US DHHS 1990, US DHHS 2000a). These same conditions also impair the health of individuals with MR. The most common causes of death among individuals with MR are cardiovascular diseases, respiratory illness and neoplastic conditions (Thase, 1982; Carter and Jancar, 1983; Dupont et al., 1987; O'Brien et al., 1991; Hayden 1998; Strauss et al., 1998; Janicki et al., 1999; Chaney and Eyman, 2000). This section will review the prevalence of these conditions among adults with MR. Cardiovascular Disease Cardiovascular disease is the leading cause of death in the U.S. and internationally, accounting for 31.4% of deaths in the U.S. general population and 30.9% of deaths in World Health Organization (WHO) member states (Hoyert et al., 1999; Turner and Moss, 1996; WHO, 1999). Manifestations of cardiovascular disease, including myocardial infarction, angina pectoris and sudden death, affect nearly 59.7 million individuals or 21.9% of the U.S. population each year (US DHHS, 2000b). Consequently, Healthy People 2000 and Healthy People 2010 have heart disease as a priority area for health improvement in the U.S. (US DHHS, 1990; US DHHS 2000a). As individuals with MR age, they suffer the same risk of cardiovascular disease as the general population. Cardiovascular disease is one of the most common causes of death among individuals with MR, accounting for 10.3% to 50.0% of deaths depending on the population studied (Carter and Jancar, 1983; Dupont et al., 1987; O'Brien et al., 1991). Prevalence estimates of cardiovascular disease in individuals with mild or moderate MR living in the community range from 6.7% to 55.2%, with individuals being at increased risk of disease as they age (Minihan, 1986; Minihan and Dean 1990; Janicki and Jacobson, 1986 and Badry et al., 1989 in Day and Jancar, 1994; Beange et al., 1995; Hand and Reid, 1996; van Schronjenstein Lantman-de Valk et al., 1997; Cooper 1998; Kapell et al., 1998). In addition, individuals with Down Syndrome are three to four times more likely to have cardiac conditions compared with individuals without Down Syndrome (Thase 1982; van Schronjenstein Lantman-de Valk et al., 1997; Kapell et al., 1998). The prevalence estimates of cardiovascular disease, however, are lower among individuals with profound MR living in institutions (O'Brien et al., 1991; Turner and Moss, 1996). For example, O'Brien et al. (1991) found that 30% of all deaths among individuals with profound MR were related to heart disease compared with 44.4% among individuals with mild to moderate MR. If the lower prevalence is, in fact, real, it may be related to either lifestyle factors that influence blood pressure, cholesterol levels, obesity, cigarette smoking and physical activity (Pitetti and Campbell, 1991; Turner and Moss, 1996), or the fact that among the institutionalized, those who live longer are healthier. Alternatively, the difference may be due to incomplete measurement of the conditions under study. For example, Ziring et al. (1988) pointed out that 8.9% of those recently deinstitutionalized had previously undetected cardiac conditions, suggesting that cardiac conditions may be underdiagnosed among individuals in institutions. Cancer The second leading cause of death in the U.S. and the United Kingdom (U.K.) is cancer, accounting for 23.3% of deaths in the U.S. and 25.0% of deaths in the U.K. (Hoyert et al., 1999; Turner and Moss 1996). Cancer deaths are primarily attributable to lung cancer (49.5 per 100,000), breast cancer (25.6 per 100,000 women), prostate cancer (25.4 per 100,000 men) and colorectal cancer (17.6 per 100,000) (Ries et al., 2000). In the U.S., nearly 40% of individuals are diagnosed with cancer during their lifetime (US DHHS, 1998). The most commonly diagnosed cancers are prostate (149.7 per 100,000 men), breast (109.7 per 100,000 women), lung (55.2 per 100,000) and colorectal (43.9 per 100,000) (Ries et al., 2000). Because cancer affects so many individuals in the U.S., the Surgeon General made early detection, treatment and prevention of cancer a national priority in Healthy People 2000 and Healthy People 2010 (US DHHS, 1990, US DHHS, 2000a). Cancer is also a health concern among individuals with MR. Cancer is among the most common causes of death among individuals with MR, with estimates ranging from 7.4% to 34.0% depending on the population studied (Carter and Jancar, 1983; Dupont et al., 1987). In fact, after adjusting for age, the prevalence of most cancers among individuals with MR living in the community is thought to be similar to that found in the general population. For example, in a study of the prevalence of cancer among older community residents with MR in the Netherlands, Evenhuis (1997) found cancer prevalence estimates similar to those in the Dutch population. He found that 22.9% of individuals with MR were diagnosed with cancer, including breast, prostate, lung, gastrointestinal and skin cancers. One exception to these similar trends is among individuals with Down Syndrome (Jancar and Jancar, 1977; Turner and Moss 1996; Scholl et al., 1982; Baird and Sadovnick, 1988; Franceschi et al, 1991; Hasle et al., 2000). For example, in a recent study examining the prevalence of leukemia and solid tumors in the Danish Cancer Registry, Hasle et al. (2000) found that children with Down Syndrome are more likely to have leukemia compared with children of the same age in the general population (children ages 0-4 years, standardized incidence ratio: 56.4; children ages 5-19 years, standardized incidence ratio: 7.7). Individuals with Down Syndrome, however, were half as likely to have solid tumors compared with the general population, even after adjusting for age. In contrast to community-based studies, in one institution in England, Cooke (1997) found that 13.6% of all deaths were due to cancer, an overall prevalence rate that was lower than the 26% found in the general population in England during the same time period. Although age-adjusted estimates were not presented, the prevalence of cancer among individuals with MR declined during a time when longevity increased in this population, suggesting that decreased life expectancy did not explain the lower prevalence of cancer among individuals with MR. Another important finding from this study was that the types of cancer varied between individuals with MR in the institution and those in the general population. In contrast to the leading cancer deaths in the general population, they found very few deaths due to lung, breast or prostate cancer; rather this study found a high proportion of gastrointestinal cancer among individuals with MR (55% in the MR population versus 26% in the general population). The high prevalence of gastrointestinal cancer was thought to be related to gastrointestinal reflux and chronic constipation that is common among individuals with MR living in institutions. Others have also documented a high prevalence of gastrointestinal cancer among individuals with MR in institutions (Jancar and Jancar, 1977). The prevalence of cancer is also associated with severity of MR. In the U.S., O'Brien et al. (1991) found that among those individuals living in one southeastern residential facility, those with mild or moderate MR were more likely to die of cancer than individuals with profound MR. Additional studies examining the prevalence of cancer in the U.S. are limited. One study that examined mortality in 14 individuals with MR in the community provided anecdotal evidence that one of the 14 individuals died of undetected cervical cancer, a potentially avoidable cause of death (Kastner et al., 1993). Cerebrovascular Disease Cerebrovascular disease is a common term to describe ischemic and hemorrhagic strokes or transient ischemic attacks that result in a lack of blood flow to the brain. This disease is the third leading cause of death in the U.S. (Hoyert et al., 1999), with an estimated 731,000 incident (first time) strokes each year (Sacco et al., 1999). It is one of the most prevalent conditions among individuals 65 and older in the U.S. (NSA, 1999; US DHHS, 2000a). In fact, more than 4 million or 4.3% of Americans 45 years and older are living with the effects of stroke (NSA, 1999). Like cardiovascular disease, the detection, prevention and treatment of cerebrovascular disease has been a national priority in Healthy People 2000 and Healthy People 2010 (US DHHS, 1990; US DHHS, 2000a). Since the population of individuals with MR is aging, the risk of cerebrovascular disease, like that of cardiovascular disease and cancer, is increasing in this population (Turner and Moss, 1996). Few studies, however, have examined the prevalence of stroke among individuals with MR. In a community-based study in England, Cooper (1998) documented a cerebrovascular disease prevalence of 9.0% among individuals with MR 65 years and older, which she noted to be greater than that of the general population (although general population estimates were not provided). No individuals with MR under 65 years of age who participated in the study had a cerebrovascular disease. In another community-based study of 70+ year olds in the Netherlands, Evenhuis (1997) found that 2.8% of individuals with MR reported a history of stroke, a prevalence estimate similar to that in the general population. Although it is unclear whether individuals with MR are more likely to have a stroke compared with the general population, it is clear that the aging MR population faces a serious risk of cerebrovascular disease. Chronic Obstructive Pulmonary Disease (COPD) and Other Respiratory Conditions Chronic obstructive pulmonary disease (COPD) is used to describe two respiratory conditions, chronic bronchitis and emphysema. Both conditions cause a shortness of breath and coughing that gets worse over time. COPD and other respiratory conditions, such as pneumonia and influenza, are the fourth and sixth leading causes of death in the U.S., respectively. COPD accounts for 4.7% of all deaths and pneumonia and influenza account for 3.7% of all deaths in the U.S. (Hoyert et al., 1999). According to the U.S. National Heart, Lung and Blood Institutes, over 13.5 million Americans report having COPD (5.1% of the U.S. population) (US DHHS, 1995). Pneumonia and influenza have seasonal variations reaching their peak prevalence in winter. They are more commonly reported among the elderly and individuals with chronic health problems than among young, healthy individuals (CDC, 2000). In the year 2000, the U.S. Centers for Disease Control and Prevention reported a prevalence of 33% of individuals infected with influenza (CDC, 2000). Western European studies find a similar prevalence of COPD, pneumonia and influenza (Lung and Asthma Information Agency, 1995; WHO, 1999). Most of the reviewed studies of individuals with MR report prevalence estimates of general respiratory conditions, inclusive of COPD and respiratory infections, although a few research efforts have focused on COPD or other specific respiratory conditions. Increased prevalence of respiratory conditions, and infections in particular, have been shown to be associated with increased age, institutional residence, severity of MR and severity of physical impairment. For example, studies conducted in the community and in institutions have shown that the probability of having a respiratory condition increases linearly with age (Janicki and Jacobson, 1986 in Day and Jancar, 1994); Day, 1987 in Day and Jancar, 1994). Additionally, there is a higher prevalence of respiratory conditions among individuals 45 years and older living in institutions (1.1% to 33%) (Nelson and Crocker, 1978; Rubin, 1987; Day, 1987 in Day and Jancar, 1994; Minihan, 1986; van Schronjenstein Lantman-de Valk et al., 1997; Evenhuis, 1997), compared with those living in the community (1.5% to 5.1%) (Janicki and Jacobson, 1986 in Day and Jancar, 1994). Specifically, individuals with MR living in institutions are highly susceptible to respiratory infections. In fact, nearly one-half of all deaths in institutions are accounted for by pneumonia and influenza, with a disproportionate number of individuals having severe or profound MR (Polednak, 1975; O'Brien et al., 1991; Turner and Moss, 1996). Differences between the prevalence of individuals living in the community and the prevalence of individuals with severe MR living in institutions are most likely related to the severity of both MR and physical impairments, as well as the associated limitations in physical activity. Among individuals living in residential facilities, for example, individuals with moderate or severe MR have been found to be more likely to have COPD compared with individuals with mild MR (van Schronjenstein Lantman-de Valk et al., 1997). Further, individuals living in institutions are more likely to be immobile and/or have difficulties swallowing and, thus, are more susceptible to respiratory infections (Turner and Moss, 1996; Kennedy et al., 1997). In addition, as a result of their congregate living arrangement, individuals with severe MR have greater exposure to infectious agents. Individuals with severe MR are not the only subpopulation of individuals with MR to suffer from high rates of respiratory infections. Researchers have also suggested that young individuals with Down Syndrome are susceptible to such infections (Baird and Sadovnick, 1988), because of accelerated immunologic aging (Nespoli et al., 1993) and physical malformations that may hinder drainage of sinuses (Saenz, 1999). Diabetes Mellitus Diabetes mellitus is a disease in which the body has an inadequate supply of insulin, a hormone needed to metabolize food into energy. Obesity is a major risk factor of diabetes (CDC, 1998), and individuals with this disease are at higher risk of heart disease, stroke, high blood pressure, blindness, kidney disease, amputations and dental disease (CDC, 1998). Diabetes is the seventh leading cause of death in the U.S. (Hoyert et al., 1999), accounting for 2.7% of all deaths. Additionally, over 15.7 million individuals in the U.S. (5.9% of the population) and over 1.4 million in the U.K. (3.0% of the population) have diabetes mellitus (CDC, 1998; Diabetes UK, 2000). With a high prevalence of the disease in the U.S., Healthy People 2000 and Healthy People 2010 have made preventing and reducing diabetes a priority in the nation's health (US DHHS, 1990; US DHHS, 2000a). Although not a major cause of death among individuals with MR, diabetes and its associated risks are important health concerns. Individuals with MR have similar prevalence estimates of diabetes as individuals in the general population. In community studies in the U.S. and in Western Europe, the prevalence of diabetes among individuals with MR has been found to be 1.6% to 9.1%, with those over 65 having a two-fold increase in the risk of diabetes compared with those less than 65 years (van Schronjenstein Lantman-de Valk et al., 1997; Cooper, 1998; Kapell et al., 1998). Further, studies examining the prevalence of diabetes among those with MR residing in institutions found a lower prevalence than that found in community-based studies of individuals with MR (.8%-2.8%) (Hogg et al., 1988 in Day and Jancar, 1994; Minihan and Dean, 1990). In addition, compared with the general population, individuals with Down Syndrome have an increased probability of being obese (Cronk et al., 1985 in Fujiura et al., 1997; Bell and Bhate, 1992). Perhaps as a result, there is some evidence to suggest that individuals with Down Syndrome have a higher probability of having diabetes and of having the disease at a younger age than individuals without Down Syndrome (Burch and Milunsky, 1969; Farquhar, 1969; Van Goor et al., 1997; Kapell et al., 1998). Unintentional Injuries Unintentional injuries (e.g., motor-vehicle, drowning, residential fires, poison consumption, falls) are the leading cause of death among young people (ages 1-34 years) and the fourth overall leading cause of death in the U.S., accounting for 4.1% of all deaths (Hoyert et al., 1999). The WHO also reports that 6.5% of deaths in WHO member states are attributed to unintentional injuries (WHO, 1999). Additionally, the NCHS reports that 31 million visits to the emergency room result from unintentional injuries each year (Burt and Fingerhut, 1998). The risk of injury is so great that most individuals will experience an unintentional injury at some point in their life. As a result of the high prevalence of injury, the Surgeon General has made reduction in mortality and morbidity due to unintentional injuries a national priority in Healthy People 2000 and Healthy People 2010 (US DHHS, 1990, US DHHS, 2000a). Individuals with MR are at least as, if not more, likely to die from an unintentional injury compared with the general population. In a British Columbia study of the causes of death among individuals with Down Syndrome aged 30 and younger, Baird and Sadovnick (1988) reported that injuries occurred in the Down Syndrome population as frequently as in the general population (prevalence estimates ranging from < .1% to 8.2%). In a population-based study of deaths in Denmark, however, Dupont et al. (1987) found that individuals with mild or moderate MR aged 15-34 years were at increased risk of death due to accidents compared with the general population of the same age. Although no studies could be found examining non-fatal accidents and injuries among adults with MR in the population, a few studies have examined sports-related injuries at Special Olympics, Inc. (SOI) events. Perlman (1994) summarizes the prevalence of sports-related injuries from SOI events in 12 states and the previous four world games, with a total of 701,988 participants. He reported an overall injury claim prevalence of .05%, with estimates ranging from .01% to .21% depending on the sporting event, although comparison to the general population is not possible since there are no comparable data for individuals without MR. McCormick et al. (1990) found a slightly higher prevalence of sports-related injuries at the Special Olympics competition in Galveston, Texas, with 3.5% of 777 athletes requiring medical care for sports-related injuries. Thus, like the general population, unintentional injuries and accidents are an important health concern among those with MR. Health Behaviors The prevalence of certain health behaviors, such as poor nutritional habits leading to obesity, decreased physical activity and smoking, has become a major concern to policy makers and researchers interested in the overall health of the nation. Obesity, physical activity and tobacco consumption are primary modifiable risk factors for most chronic diseases, and, as such, are listed among the leading health indicators for health in Healthy People 2000 and Healthy People 2010 (US DHHS, 2000a). Obesity Obesity is associated with cardiovascular disease, breast, prostate and colon cancers, cerebrovascular disease and diabetes (National Task Force, 2000). According to Healthy People 2010, the number of overweight individuals has risen in the past four decades, with 11% of children ages 6 to 19 years being overweight or obese and 23% of adults being obese between 1988-1994 (US DHHS, 2000a). Obesity is more common among individuals with MR than in the general population, with overall prevalence estimates ranging from 29.5% to 50.5% (Simila and Niskanen, 1991; Bell and Bhate, 1992, Rimmer et al., 1993; Rubin et al., 1998). In fact, in a convenience sample of select participants, Touger-Decker and Matheson (2000) found that more than 66.0% of children with MR who participated in the New Jersey 2000 Special Olympic Games were overweight. The prevalence of obesity in the MR population has been found to vary with living situation and etiology of MR. Individuals living at home have the highest prevalence of obesity (55.3%) followed by those living in a group home (less than 16 residents) (40.9%), while individuals living in institutions (more than 100 residents) have the lowest prevalence of obesity (16.5%) (Rimmer et al., 1993; Prasher, 1995). In addition, individuals with Down Syndrome are 1.5 times more likely to be obese compared with individuals with other etiologies of MR (Bell and Bhate, 1992). With the majority of individuals with MR living in the community, it is imperative that obesity be considered a major health problem facing individuals with MR. Physical Activity Regular physical fitness is an important health maintenance activity that is associated with decreased body fat, decreased risk of cardiovascular disease and diabetes and enhanced psychological well-being (US DHHS, 2000a). The U.S. Surgeon General has made regular physical activity a national health priority in Healthy People 2000 and Healthy People 2010 (US DHHS, 1990, US DHHS, 2000a). Among adults in the general population, only 15% participate in regular physical activity of 30 minutes per day and 40% engage in any leisure physical activity (US DHHS, 2000a). Like individuals in the general population, individuals with MR are unlikely to participate in physical activities, either because they lack the motivation or the opportunity to be involved in fitness programs (Rimmer, 2000). Few studies, however, exist on the prevalence of individuals with MR participating in routine physical activity. One study examined the leisure activities of 207 adults with MR living at home in Dublin, Ireland. In this study, McConkey et al. (1981) found that most individuals with MR ages 15-64 participated in activities that were sedentary, such as watching television (73.4%) and listening to the radio or records (41.1%). The prevalence of individuals with MR participating in outdoor sports ranged from 21.1% to 47.5%, with those more physically and mentally impaired being less likely to participate in outdoor sports. Although comparison to the general population is difficult given the lack of age-stratified information presented in the study, McConkey et al. (1981) reported the prevalence of physical exercise among non-retarded children 16-24 years as 44.0%. No information was presented on the prevalence of participation in outdoor sports. In a more recent U.K. health screening study of 120 individuals with MR living in the community, Martin et al. (1997) found that 48.2% had done some physical activity over the past four weeks compared with 93.5% in the general population. More research has been done on cardiovascular fitness among individuals with MR (Beasley, 1982; Pitetti and Campbell 1991; Pitetti et al., 1993; Fernhall, 1993; Fernhall et al. 1998; Lancioni and O'Reilly, 1998). Cardiovascular fitness, an important aspect of physical activity, is related to the ability to perform light to moderate levels of physical labor. Fernall (1993), in a review of physical fitness among individuals with MR, reports that adults with MR have lower cardiovascular fitness levels than the general population, suggesting that individuals with MR may lead more sedentary lifestyles. Others have also found that individuals with MR have lower cardiovascular fitness levels compared with those in the general population (Pitetti and Campbell; 1991). SOI has recognized the need for individuals with MR to have the opportunity to participate in physical activities, including team and individual sports. SOI provides year-round opportunities for individuals with MR to participate in sports training and athletic competition, with one of the explicit goals being development of physical fitness (SOI, 2000). Besides the primary athletic competition program, SOI also has developed basic fitness guides and training materials for SOI coaches to raise awareness of proper diet and nutrition among athletes. Further, these guides encourage athletes to participate in daily exercise not only during SOI programs but also in their own home (Todd, personal communication). Additionally, SOI has developed four specific programs to encourage individuals at increased risk for sedentary lifestyles to participate in physical activities. These programs include a motor activities training program for individuals with severe MR, a unified sports program integrating individuals with mild MR with their peers without MR, a play activities program for young children with MR ages 6 and 7 years and an athlete leadership training program (Sharkey and Hunt, 1999). Smoking Cigarette smoking is a major preventable cause of disease and death in the U.S. and internationally (US DHHS, 2000a; WHO, 2000). Smoking is a major risk factor for most of the major health conditions discussed above, including cardiovascular disease, cancer, cerebrovascular disease and lung disease. In 1997, 24% of adults in the U.S. reported smoking cigarettes (US DHHS, 2000a). As a result, the Surgeon General and the WHO has made reduction in tobacco consumption a national and international health priority (US DHHS, 2000a; WHO, 2000). Prevalence estimates of tobacco consumption by individuals with MR vary by living condition and severity of MR. In a community-based study in the southern area of Melbourne, Australia, Tracy and Hosken (1997) found that 36% of individuals with MR sampled indicated that they smoked cigarettes compared with 26% in the general population. In a clinic-based study conducted in New Jersey, Hymowitz et al. (1997) found that 30% of 64 adults with mild MR reported that they were current smokers, which is only slightly higher than the smoking prevalence estimate for the U.S. general population. Burtner et al. (1995) examined the consumption of tobacco in a Florida residential facility for individuals with MR. With a prevalence estimate similar to that of the general population in 1995, they found that 20.5% of individuals with mild or moderate MR used tobacco products, including cigarettes, chewing tobacco, cigar and snuff. In comparison, only 4.3% of individuals with severe or profound MR used tobacco products. In a study of cardiovascular risk factors, Rimmer et al. (1994) examined the prevalence of smoking 10 cigarettes a day among individuals with MR living in a residential facility, living in a group home and living at home with family. They found that individuals with MR in the group home had the highest prevalence of smoking (20.8% of men and 6.7% of women) compared to individuals with MR living at home (6.9% of men and 2.1% of women) and individuals with MR living in an institution (3.8% of men, 0.0% of women). These studies suggest that individuals living in institutions and individuals with more severe MR are less likely to smoke, while individuals living in group homes and individuals with less severe MR have smoking habits similar to the general population. The prevalence of smoking also has been studied in select SOI populations, with prevalence estimates below those observed in community-based and institution-based studies. Among 704 Special Olympic athletes who participated in the 1996 New Jersey Special Olympic Special Smiles program, 7.0% reported that they currently smoked (Feldman et al., 1997). A similar smoking prevalence of 4.3% was found among Special Olympic athletes who participated in the 1997 San Francisco Bay Area Special Olympics Special Smiles program (White et al., 1998). There is some evidence, however, that smoking status may not be accurately measured by self-report among individuals with MR. In a recent study at the 2000 New Jersey Special Olympic Games, 70 SOI atheletes aged 18 to 78 were asked to identify their smoking status and to complete a carbon monoxide (CO) test of smoking status. Among those who identified themselves as smokers, 27% had negative CO test results. Among those who identified themselves as non-smokers, 18% had positive CO test results (Giniger, 2000). Thus, although some studies have shown a lower prevalence of smoking among select populations of individuals with MR, the self-reported data from these studies may not adequately reflect the true prevalence of the population. Many of the studies reported here suggest that individuals with mild or moderate MR and individuals living in group homes are as likely to consume tobacco products as individuals in the general population. Therefore, smoking education and prevention efforts are as essential for this population as it is in the general population. Child Health Conditions and Prevention Measures Otits media, asthma, child maltreatment and immunizations, were put forth as research priorities in the children's health arena by the Agency for Health Care Policy and Research, now called the Agency for Healthcare Research and Quality (US DHHS, 1997a). Although these conditions and prevention measures are areas of concern among children in the general population, and, thus, among children with MR, little information is available on the prevalence and long-term consequences of these illnesses and behaviors among children with MR. Otitis Media Young children are particularly susceptible to otitis media, or middle ear infections, because they have developing immune systems that have difficulty fighting infections, immature eustachian tubes that prevent optimal fluid drainage, and may have enlarged adenoids that interfere with the eustachian tube opening. Otitis media not only can cause severe pain, but, if left untreated, also can cause permanent hearing loss (US DHHS, 1997b). Additionally, recurrent otitis media can have a negative impact on speech and language development, cognitive achievement and social and emotional development (Evenuis and Nagtzaam, 1997). Otitis media is one of the most prevalent childhood conditions, affecting 75% of children under the age of 3 years at least once (US DHHS, 1997b). An estimated 17% to 29% of infants have one episode of acute otitis media and an estimated 26% of preschool children in the United States have recurrent otitis media (Lanphear et al., 1997). The prevalence of otitis media among children with MR has not been adequately explored. There are some reasons to believe that children with Down Syndrome are at increased risk of middle ear infections due to midfacial malformations and increased susceptibility to infections (Saenz, 1999). Although not focused specifically on otitis media, one study of 293 residents of an English institution found that 40% of individuals with Down Syndrome and 29% of individuals with MR without Down Syndrome had ear, nose and throat conditions (Donague and Abbas, 1972). Dahle and McCollister (1986) compared the prevalence of ear problems in children with Down Syndrome to children with other forms of MR. They found that hearing impairment and infections were more prevalent among children with Down Syndrome. Given the potential impact of otitis media on development (Whiteman et al., 1986), early identification of middle ear infections among children with MR, who are already at risk for delays, is important. Pediatric Asthma Asthma is characterized by recurrent breathing problems brought on by inflammation of the lining of the lungs. The severity of asthma, as with most conditions, varies by individual. While some individuals are severely limited in their activities by the condition, others have only periodic symptoms of the disease. The negative consequences of asthma, however, can be avoided with appropriate disease management. Since 1980, the prevalence of asthma has been on the rise in all age, race and sex groups. In 1980, 4.2% of children were affected by asthma, but by 1994 the prevalence of asthma rose to 7.4% of children, a 74% increase over a 24-year period (US DHHS, 2000c). Little research has been done on the prevalence of asthma among children with MR. In a study of health status and needs of children with MR, Ackland and Wade (1995) reported the prevalence of medical conditions of 249 students in Victoria, Australia. With a prevalence estimate similar to that in the U.S. population of children, asthma was diagnosed among 6.4% of the children with MR. No research exists on the negative consequences of asthma (such as reluctance to participate in physical activities) or on asthma management among children with MR, although one British study examined deaths from asthma in individuals less than 45 years old with MR. Reviewing death certificates of all residents in Southmead Health Authority, Stuart et al. (1990) found a high prevalence of asthma mortality among 5-44 year olds, with a morality rate twice that of the general U.K. population. Making confidential inquiries into the factors associated with the deaths, they found that several factors contributed to the high mortality rate, including communication difficulties between the patient and caregiver or provider, and delays in providers responding to an asthma attack. Given that disease management may be more difficult with children with MR who have limited communication skills compared with their peers without MR, increased attention should be given to self and caregiver management of this common childhood disease. Child Maltreatment Maltreatment is an all too common childhood condition in the U.S., with approximately 984,000 children being victims of substantiated or indicated abuse or neglect in 1997 (US DHHS, 1999). The most common form of maltreatment is neglect (54% of victims), followed by physical abuse (24%), sexual abuse (13%), emotional maltreatment (6%) and medical neglect (2%). It is estimated that 1,196 of nearly one million victims of child maltreatment died from abuse or neglect in 1997 (US DHHS, 1999). These estimates are based on reports by child protective services, which only account for those select cases that are known to agencies, and, therefore, may under-represent the true prevalence of child maltreatment. Children with MR also face serious consequences from abuse and neglect, although there is limited research on overall prevalence estimates of maltreatment in this population. As Waldman et al. (1999) point out, children who are abused are over four times as likely to have MR compared with non-abused children (Sullivan and Knutson, 1994 in Mansell et al., 1998). The causal direction in the association of child maltreatment and MR, however, is not clear. Physical abuse and neglect may result in MR (due to brain damage) or individuals with MR may be more likely to be abused and neglected. In a study of 445 intellectually handicapped children in Castilla-Leon, Spain, Verdugo et al. (1995) interviewed professionals about signs of abuse and/or neglect. They found that 11.5% of children with an intellectual handicap aged 0-19 years had some evidence of maltreatment compared with 1.5% of children with no intellectual handicap. Among those who had evidence of maltreatment, 92% experienced physical neglect, 82% experienced emotional neglect, 65% experienced emotional abuse and 31% experienced physical abuse and 2% experience sexual abuse. In addition, sexual abuse appears to be more prevalent among children with MR compared with children in the general population. Although not strictly focused on children with MR, Crosse et al. (1993) reported that children with disabilities are 1.8 times more likely to experience sexual abuse compared with children without disabilities (in Mansell et al., 1998). Other researchers have also found an increased prevalence of sexual abuse among children with disabilities (Sobsey and Varnhagen, 1989; Sobsey and Doe 1991; Sobsey 1994 and Valenti-Hein and Schwartz, 1995 in Reynolds, 1997). Several researchers have speculated about the reasons for the increased prevalence of abuse among individuals with MR, and have cited stress and strain on the family, unrealized parental expectations of the child, emotional and social isolation of caregivers, children's inability to report abusive experiences, children's dependency on caregivers and lack of awareness about abusive situations as potential contributors (Solomons, 1979; Reynolds 1997; Waldman et al., 1999). Although there may exist a detection bias in who is identified as a victim, it is clear that individuals with MR are at least as, if not more, likely to experience maltreatment compared with their peers without MR. Immunizations Vaccines which prevent infectious diseases and death are considered one of the most important public health achievements of the 20th century (US DHHS, 2000a). As such, vaccinations of children has remained a national health initiative in both Healthy People 2000 and Healthy People 2010 (US DHHS, 1990; US DHHS, 2000a). In 1998, 73% of children in the U.S. received routine vaccinations, including immunizations against Hepatitis B, diphtheria, tetanus, pertussis, polio, measles, mumps, rubella and Haemophilus influenzae type b (US DHHS, 2000a; American Academy of Pediatrics, 2000). Information on the immunization status for children with MR is sparse. In an early study of the medical care received by previously institutionalized children, Schor et al. (1981) found that 77.0% had up to date immunizations compared with 91.0% of children in the general population. Another study has examined the prevalence of routine immunizations among children with MR living in the community. McLaughlin et al. (1977) examined the immunization records of 134 children in a large northwestern school district, a sample population that may be generalizable only to the enrolled school population of children with MR and not to the institutionalized MR population. They found no statistical difference in the prevalence of completed immunizations between the 67 children with MR and the 67 age-, sex- and socioeconomic status-matched peers without MR (91% versus 81%, respectively). Several studies have been conducted examining the prevalence and effectiveness of the Hepatitis B vaccine among children and adults with MR (Vajro et al, 1992; Arulrajan et al., 1992; Vellinga et al., 1999). These studies suggest that individuals with MR, specifically those with Down Syndrome and those residing in institutions, are at increased risk of Hepatitis B infection (Vellinga et al., 1999). Vajro et al. (1992) examined the seroconversion rate (the antibody response to a vaccine, which indicates that the vaccine was effective and that an individual is immune to the disease) of preschool children with Down Syndrome compared with children with other forms of MR. Despite prior evidence suggesting that individuals with Down Syndrome are more likely to lack an anti-Hepatitis B response compared with general population controls, they found that children in both groups had a complete seroconversion. Given that children with MR, in particular those with Down Syndrome and those in institutions, are at increased risk of infection, administration of routine vaccines in this population is imperative. Health Conditions Among Those with Down's Syndrome and Rationale for Increased Prevalence Certain health conditions are particularly prevalent among individuals with Down Syndrome and warrant further discussion. For example, conditions such as orthopedic anomalies, congenital heart defects and thyroid disease, although relatively infrequent in the general population, can be life-threatening conditions for individuals with Down Syndrome. Atlantoaxial Instability Individuals with Down Syndrome have many orthopedic anomalies, but few are as life threatening as atlantoaxial instability. Atlantoaxial instability is a laxity in the movement between the first and second cervical vertebrae and, thus, increases the risk of spinal cord injury (Msall, 1999). It occurs in 10% to 40% of individuals with Down Syndrome, depending on the child's age and definition of instability (Tishler and Martel, 1965 and Alvarez and Rubin, 1986 in Cremers et al., 1993; Cope and Olson, 1987; Rubin, 1987; Pueschel and Scola, 1987; Pueschel, 1998). Despite the relatively high prevalence of atlantoaxial instability, there is no information about the prevalence of screening among individuals with MR, which may be due in part to the controversy surrounding the safety of the radiograph screening process and the questionable diagnostic value of the procedure (Pueschel, 1998). Therefore, effective and safe health screening procedures for asymptomatic atlantoaxial instability is an important consideration, in need of further exploration. Some researchers and providers, in fact, believe that atlantoaxial instability may limit an individual's ability to participate safely in sports (Saenz, 1999; Msall, 1999), while others have found restriction of activity based on the possibility of increased instability to be unnecessary for most children with Down Syndrome (Cremers et al., 1993; Morton et al. 1995). Congenital Heart Defects Children with Down Syndrome are significantly more likely to have a congenital heart defect than individuals in the general population. Approximately 40% to 60% of children with Down Syndrome have a heart defect (Spicer, 1984; Pueschel, 1990; Martin, 1997) compared with 0.8% in the general population (Mitchell et al., 1971; March of Dimes, 1999). Due to advancements in medical technology, however, survival for children with heart defects has dramatically improved (March of Dimes, 1999). Consequently, some physicians recommend that infants with Down Syndrome have electrocardiogram and echocardiogram screenings so that those in need can be referred to a specialist for medical management (Pueschel, 1990; Saenz, 1999). No studies were found that determine the screening rate of congenital cardiac conditions among individuals with Down Syndrome, however. Thyroid Disease Diseases of the thyroid, the organ that regulates the body's metabolism, can lead to blood pressure disturbances, fatigue, changes in appetite, weight disturbances, difficulty with concentration and changes in gastrointestinal regulation (Thyroid Society, 2000). Thyroid disease affects nearly 20 million or 1.4% of Americans (Thyroid Society, 2000). Compared with the general population, individuals with Down Syndrome have an increased probability of having a thyroid disorder, including hypothyroidism or hyperthyroidism, with prevalence estimates ranging from 3% to 50% depending on the population studied and criteria for diagnosis (Rubin, 1987; Pueschel, 1990; Dinani and Carpenter, 1990; Ali et al., 1999). Unlike individuals in the general population, who are at increased risk of thyroid disease with increased age, individuals with Down Syndrome are more likely to have thyroid disease at an earlier age. Those with Down Syndrome are thought to be at increased risk of thyroid disease because they often have autoimmune abnormalities (Kennedy et al., 1992; Ali et al., 1999) and accelerated immunologic aging (Nespoli et al., 1993). Only one study could be found that examined the screening rate of thyroid disease among children with Down Syndrome. In an interview with Australian parents who attended a conference on Down syndrome, Selikowitz (1992) found that 64.7% of 132 school-aged children with Down Syndrome had been tested for hypothyroidism within the past 18 months. Even within this highly motivated and, presumably, informed population, then, the screening rate of thyroid disease was relatively poor. Because thyroid disease is so common among children with Down Syndrome, regular screening and early detection of thyroid conditions is essential (Murdoch et al., 1977 in Martin, 1997; Noble et al., 2000). Summary and Implications Similar to individuals in the general population, individuals with MR are at risk for chronic medical conditions, including cardiovascular disease, cancer, cerebrovascular disease, lung conditions and diabetes. Individuals with MR are also susceptible to the primary risk factors of chronic diseases including obesity, decreased physical activity and smoking. As in the general population, the risk of disease among those with MR increases with age. In addition, the disease prevalence varies by severity of MR. Individuals with mild or moderate MR are more likely to have cardiovascular disease and diabetes compared with individuals with severe or profound MR, while those with severe or profound MR living in institutions are more likely to have respiratory conditions compared with individuals with mild or moderate MR. Further, one group of individuals with MR, those with Down Syndrome, who have autoimmune abnormalities, are at increased risk of cardiovascular disease, leukemia, respiratory disease and diabetes. Not surprisingly, the risk factors associated with these diseases are more prevalent among those with Down Syndrome, namely obesity and decreased physical activity. Besides the common adult health conditions, individuals with Down Syndrome are also more likely to have diseases that are less common among individuals in the general population, including atlantoaxial instability, congenital cardiac conditions and thyroid disease. Although common childhood conditions, such as otitis media, asthma and child abuse, have also been reported among children with MR, very little information exists about the prevalence or manifestations of these conditions in children with MR. The research that does exist suggests that children with MR are at increased risk of otitis media and of being maltreated. Despite these increased risks of health conditions, however, little research exists on effective prevention programs and treatment strategies for this group of children and adults. One example of this lack of attention is the paucity of information on the immunization status of children with MR, one important public health measure. In addition, as will be discussed in a subsequent chapter, although individuals with MR have similar physical health problems as those in the general population, they are less likely to receive adequate medical services compared with those in the general population. References