Executive Summary

The U.S. Social Security Administration (SSA) asked the National Research Council to assess its disability determination process for mental retardation. The Committee on Disability Determination for Mental Retardation was formed to evaluate the existing determination process in the context of state-of-the-art scientific knowledge and clinical practice. The committee was also asked to suggest new procedures that may be necessary to ensure that SSA eligibility determinations are based on procedures and criteria that conform to best professional practices and to identify promising areas of research that may help to clarify unaddressed or incompletely answered questions.

Mental retardation is a condition characterized by significant deficits in intellectual capabilities and adaptive behavior. Its onset occurs during the developmental period, the period through age 21. The diagnosis can be particularly difficult to make in the mild range of retardation, in which adaptive behavior deficits are less easily quanti-



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Mental Retardation: Determining Eligibility for Social Security Benefits Executive Summary The U.S. Social Security Administration (SSA) asked the National Research Council to assess its disability determination process for mental retardation. The Committee on Disability Determination for Mental Retardation was formed to evaluate the existing determination process in the context of state-of-the-art scientific knowledge and clinical practice. The committee was also asked to suggest new procedures that may be necessary to ensure that SSA eligibility determinations are based on procedures and criteria that conform to best professional practices and to identify promising areas of research that may help to clarify unaddressed or incompletely answered questions. Mental retardation is a condition characterized by significant deficits in intellectual capabilities and adaptive behavior. Its onset occurs during the developmental period, the period through age 21. The diagnosis can be particularly difficult to make in the mild range of retardation, in which adaptive behavior deficits are less easily quanti-

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Mental Retardation: Determining Eligibility for Social Security Benefits fied with commonly used instruments. Differences in content, standardization, and floor and ceiling effects on broadly used measures of adaptive behavior, as well as different conceptualizations of the nature of adaptive behavior, all contribute to this difficulty. Current estimates suggest that anywhere from 1 to 3 percent of people living in the United States will receive a diagnosis of mental retardation. These varying prevalence estimates reflect (1) differences in the way that mental retardation is defined, interpreted, and measured; (2) differences in the ways in which students are identified in urban and rural education systems; and (3) whether individuals or their families from varying cultural, racial, and ethnic backgrounds choose to apply for services. In addition, definitions of mental retardation vary, with SSA, the major professional organizations, and the World Health Organization all providing different definitions of the condition. SSA provides income support and medical benefits to many individuals with mental retardation. Benefits are provided to adults unable to perform substantial gainful activity (i.e., work) because of mental retardation through the Disability Insurance (DI) program and the Supplemental Security Income (SSI) program. SSI benefits are provided as well to the families of children and adolescents who evidence “marked and severe” restrictions in functioning because of mental retardation. The determination decisions are made through state disability determination services, with payments coming from the federal agency and, in some jurisdictions, supplemented by state resources. COMMITTEE CHARGE Specifically, the committee has been asked to (a) examine the adequacy of the SSA definition of mental retardation, (b) comment on the current procedures for assessing intellectual capabilities and indicate how best to make that assessment consistent with current science and professional practice, (c) discuss the issue of adaptive behavior and its assessment consistent with current science and widespread professional practice, (d) provide advice on the most appropriate ways of

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Mental Retardation: Determining Eligibility for Social Security Benefits combining data from intellectual and adaptive functioning in order to provide a complete profile of an individual’s capabilities, and (e) clarify ways of better differentiating mental retardation from other conditions with which it shares signs and symptoms. The committee has also been asked to provide suggestions for research or evaluation that could clarify unaddressed or incompletely answered issues. This report answers these questions and makes specific recommendations as well. ADEQUACY OF THE SSA DEFINITION Although no single definition of mental retardation is universally accepted in all its details, intellectual deficits are central to all such definitions. The consensus of the major professional associations and health-related organizations is that mental retardation involves deficits in intellectual functioning and adaptive behavior and has its onset during the developmental period. Their definitions differ from each other on a number of critical specifics, including the nature and measurement of the deficits in adaptive behavior and the age of onset. SSA’s definition of mental retardation includes the criteria used by these authoritative sources. However, it diverges from the standard diagnostic nomenclature in some ways, including the nature and assessment of deficits in adaptive behavior, its basis for determining subaverage intellectual functioning, and the age of onset. In addition, the SSA definition goes beyond the criteria used by these other organizations in identifying individuals as having mental retardation if they have both deficits in intellectual functioning and comorbid medical or psychiatric disorders—a circumstance addressed by no other definition of mental retardation. It is important to note that the differences between the SSA definition of mental retardation and those of the major professional and health-related organizations derive from the purpose for which it is used. The SSA definition is used not for diagnostic purposes, but rather for purposes of program eligibility. The SSA definition fulfills its purpose of identifying individuals with cognitive limitations who

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Mental Retardation: Determining Eligibility for Social Security Benefits experience significant problems in their ability to perform work and may therefore be in need of governmental support. However, the committee recommends specific changes to the SSA definition, related to the criteria for intellectual functioning and adaptive behavior. The committee’s proposed changes are detailed in the recommendations that follow. INTELLIGENCE AND ITS ASSESSMENT SSA and the major professional associations and health-related organizations all define mental retardation in terms of deficits in intellectual functioning that are approximately two standard deviations below the mean of the population on commonly used intelligence tests. In contrast to the position taken by the other organizations, which focuses on the composite intelligence score, SSA allows the use of partial or part scores in a determination of mental retardation. For instance, when either the verbal or performance IQ on Wechsler measures is at least two standard deviations below the mean, a person could be deemed to have met the intellectual functioning criterion for mental retardation. Although SSA says that it will accept part scores from any individually administered, standardized IQ test, it uses part scores from the Wechsler measures in its regulations as an example. The presumably unintended consequence of that example is that, in clinical practice, the Wechsler measures are used most frequently for disability determination. In the committee’s judgment, composite scores from intelligence tests should be used routinely in mental retardation diagnosis, except when the composite IQ score’s validity is in doubt, in which case an appropriate part score may be used in its place. Significant and meaningful variation among an instrument’s respective part scores may indicate evidence of compromised validity for one or more of them (for example, a low verbal scale score for an individual with a suspected speech disorder), which in turn would threaten the validity of the composite IQ score. In such situations, appropriate part scores may better represent the individual’s true overall level of cognitive functioning.

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Mental Retardation: Determining Eligibility for Social Security Benefits Only part scores derived from scales that demonstrate high g-loadings—that is, ones that are better representations of general intellectual ability (e.g., crystallized, fluid measures of intelligence)—should be used in place of the composite IQ score when its validity is in doubt. Many intelligence tests access several facets of intelligence, but not all facets are equally important or predict life events equally well. Those intellectual facets that are heavily “g-saturated” provide the best sources for replacing the composite IQ score when its validity is questionable. The committee makes the following recommendation related to intelligence and its assessment. Recommendation: A client must have an intelligence test score that is two or more standard deviations (SD) below the mean (e.g., a score of 70 or below, if the mean = 100 and the standard deviation = 15). Composite score is 70 or below: If the composite or total test score meets this criterion, then the individual has met the intellectual eligibility component.1 Composite score is between 71 and 75: If the composite score is suspected to be an invalid indicator of the person’s intellectual disability and falls in the range of 71-75, a part score of 70 or below can be used to satisfy the intellectual eligibility component. Composite score is 76 or above: No individual can be eligible on the intellectual criterion if the composite score is 76 or above, regardless of part scores.2 1   Discussion of the rare instance in which a composite IQ is 70 or below but is suspected to be invalid is in Chapters 3 and 5. 2   Committee member Keith Widaman dissents from this part of the recommendation. Dr. Widaman believes that IQ part scores representing crystallized intelligence (Gc, similar to verbal IQ) and fluid intelligence (Gf, related to performance IQ) have clear discriminant validity and represent broad, general domains of intellectual functioning.

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Mental Retardation: Determining Eligibility for Social Security Benefits The committee recommends continuation of the criterion of presumptive eligibility for persons with IQs below 60. The use of part scores, most often from the Wechsler measures, introduces an important consideration in the clinical use of intelligence measures for disability determination. Current scientific conceptions of intelligence focus primarily on fluid and crystallized abilities, with recognition that working or comprehensive memory is also important to overall intellectual functioning. Many intelligence tests are based on these distinctions. The Wechsler measures are also moving in this direction, with a focus on factor scores that are analogous to crystallized intelligence (e.g., verbal comprehension index), fluid intelligence (e.g., perceptual organization index), and working/comprehensive memory (e.g., working memory index). Consequently, the committee has recommended continued use of part scores in eligibility determination, but is advocating use of part scores that are consistent with current scientific thinking. ADAPTIVE BEHAVIOR AND ITS ASSESSMENT Deficits in adaptive behavior, together with deficits in intelligence, are also central to current definitions of mental retardation. SSA and the major professional organizations disagree on the nature and degree     Therefore, a score of 70 or below on either of these part scores from any standardized, individually administered intelligence test that reports such scores should be deemed sufficient to meet the listings for low general intellectual functioning regardless of the level of the composite score, providing that the part scores have adequate psychometric properties (e.g., high reliability, low standard error of measurement). Dr. Widaman notes that, without any clear justification, SSA currently accepts either a composite IQ score from any standardized, individually administered intelligence test or a verbal or performance IQ score, any one of which can be 70 or below. SSA does not stipulate that the composite IQ must be below a certain score for a part score to be used. Dr. Widaman’s position provides a rationale for current SSA use of part scores, but it (a) aligns the acceptable part scores with the constructs of Gc and Gf used in contemporary theories of mental abilities and (b) argues that usable part scores for Gc and Gf should not be limited to those derived from any particular test instrument.

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Mental Retardation: Determining Eligibility for Social Security Benefits of adaptive behavior deficits that must be apparent before a diagnosis of mental retardation can be made. There are also differences in how these behavioral deficits are to be measured, with SSA, the American Association for Mental Retardation, and the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition suggesting that behavioral descriptions of adaptive functioning are sufficient, and Division 33 of the American Psychological Association and the World Health Organization requiring the use of standardized assessment measures. The committee’s judgment is that the approach currently taken by SSA can result in inconsistent decision making, because different types and quality of information are used in making the determination. The committee makes the following recommendations related to adaptive behavior and its assessment. Recommendation: Standardized adaptive behavior instruments should be used to determine limitations in adaptive functioning. In general, the cutoff scores for adaptive behavior should be one standard deviation below the mean in two adaptive behavior areas or one and one-half standard deviations below the mean in one adaptive behavior area. Adaptive behavior measures should be used whenever possible, but only when there is an instrument that matches the client’s characteristics and when an appropriate third-party respondent is available. A client can be determined to have a significant limitation in adaptive functioning even with scores that do not meet the above criteria if there is compelling evidence of adaptive behavior deficits that significantly impair performance of expected behaviors. Recommendation: Revisions should be made in the adaptive behavior areas or domains emphasized in SSA regulations to conform to factor analytic results. The following areas by age should be adopted by SSA:

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Mental Retardation: Determining Eligibility for Social Security Benefits Infancy/early childhood (approximate ages birth to 4): motor/ mobility, social, communication, daily living skills (self-help). Childhood (approximate ages 5 to 17): motor/mobility, social, communication/functional academic skills, daily living skills. Adolescence/adulthood (approximate ages 18 and older): motor/mobility, social, communication/practical cognitive skills, daily living skills, work skills/work-related behaviors. COMBINING IQ AND ADAPTIVE BEHAVIOR DATA Interpreting the combination of data on intelligence and adaptive behavior functioning is at the crux of making mental retardation disability determinations, particularly for individuals whose intellectual functioning hovers around an IQ of 70. The committee recognizes that this is a very difficult task. Studies have estimated the relationship between IQ and adaptive behavior ranging from 0 (indicating no relationship), to almost +1 (indicating a perfect relationship). Data also suggest that the relationship between IQ and adaptive behavior varies significantly by age and levels of retardation, being strongest in the severe and moderate ranges and weakest in the mild range. There is a dearth of data on the relationship of IQ and adaptive behavior functioning at the mild level of retardation, affecting the group that is most difficult to assess for the SSA determination process. Consequently, in the committee’s view, informed, trained judgments are needed in decisions about how to assess these core dimensions of mental retardation and how to interpret the findings that result. The committee makes the following recommendations with respect to combining these two types of data to determine whether an individual has mental retardation for disability benefit purposes. Recommendation: A diagnosis of mental retardation should be based on high-quality assessments of intellectual and adaptive functioning that meet the following criteria:

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Mental Retardation: Determining Eligibility for Social Security Benefits A broad variety of information on adaptive behavior and intelligence should be collected, including data on performance in different settings, from different sources, and using varying methods. Comprehensive, multifactored measures of intelligence and adaptive behavior should be used in mental retardation eligibility determination. Brief, unidimensional measures or short forms of comprehensive tests should not be used. The principle of convergent validity shall be applied in eligibility decisions about mental retardation. Information that is inconsistent with a diagnosis of mental retardation should be recognized, evaluated, and explained in the overall diagnostic decision. Assessments must be conducted by people with appropriate education and training for the kind of instrument used and the nature of the eligibility decision to be made. People conducting intellectual assessments must meet test publishers’ requirements for Class C instruments. Measures of adaptive and intellectual functioning should be carefully selected and interpreted in order to minimize the negative effects of low validity, low reliability, floor and ceiling effects, and steep item gradients. The norms for measures of adaptive behavior and intellectual functioning must be suitably contemporary. Use of outdated norms or previous editions of recently restandardized measures is not acceptable. The norms for intellectual measures should be no older than 12 years because of the deterioration of normative standards over time. Decisions about eligibility for a diagnosis of mental retardation should be made by people with appropriate preparation in the areas of mental retardation and other disabilities and disorders, measurement of intellectual and adaptive functioning, knowledge of human development, and the influence of context on behavior.

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Mental Retardation: Determining Eligibility for Social Security Benefits DIFFERENTIAL DIAGNOSIS Distinguishing mental retardation from other disorders with similar behavioral and cognitive signs and symptoms is referred to as differential diagnosis. SSA has had particular difficulty differentiating mental retardation from other disorders in children and adolescents. Following recent legal and legislative action, including the Supreme Court decision in Sullivan v. Zebley, the Personal Responsibility and Work Opportunity Reconciliation Act of 1996, and the Balanced Budget Act of 1997, SSA inappropriately declassified some children who had been previously determined to have mental retardation for purposes of receiving disability benefits. Consequently, the agency asked the committee for advice on how best to differentiate conditions that share signs and symptoms with mental retardation. These conditions include autism and other pervasive developmental disorders, learning disability, and borderline intellectual functioning, as well as others. The committee makes the following recommendations relevant to differential diagnosis. Recommendation: Social Security Disability Determination Specialists may differentiate other conditions from mental retardation by using intelligence and adaptive behavior test criteria as outlined in the committee’s recommendations. Data, including school test results, intelligence and adaptive behavior test results, and psychiatric and medical test results, from community-based agencies (such as schools, hospitals, or clinics) can be used to inform the determination of SSA eligibility for the diagnosis of mental retardation, but the diagnoses given by community agencies should not be used. Social Security Disability Determination Specialists may differentiate individuals with borderline intellectual functioning and learning disability from those with mental retardation by reviewing cognitive and adaptive behavior test results and determining whether the individual meets diagnostic criteria for

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Mental Retardation: Determining Eligibility for Social Security Benefits mental retardation as outlined in the committee’s first two recommendations. Social Security Disability Determination Specialists do not need to determine the presence or absence of mental retardation in individuals who are eligible for SSI due to other neurodevelopmental or psychiatric disabilities (e.g., autism, pervasive developmental disorder, attention deficit hyperactivity disorder, genetic syndromes, intrauterine exposure to alcohol or environmental toxins, sensory impairments, seizure disorders, or severe emotional-behavioral disorders). Objective data on intellectual and adaptive functioning to determine mental retardation should be collected for individuals with mild neurodevelopmental or psychiatric disabilities who might have impairments that are consistent with or functionally equivalent to mental retardation. SSA PROGRAMS IN CONTEXT The committee frames its response to SSA’s charge in terms of the specific context of the DI and SSI disability benefit programs. These programs provide needed support to children and their families and to adults with mental retardation. Individuals with mental retardation constitute the largest diagnostic category of children receiving SSI— 26 percent. The total number of individuals receiving SSA benefits for mental retardation is more than 1 million. These programs not only provide benefits to a large number of people, but also serve as a critical gateway to a number of other federal and state benefits. This linkage is particularly important because of the difficulty that individuals with mental retardation have in securing and maintaining substantial gainful employment. Thus, the accuracy of a diagnosis of mental retardation is important to both the client and SSA: false positives allow people into the system who should not be receiving benefits and thus strain its resources, but false negatives not only deny SSI and DI benefits to those

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Mental Retardation: Determining Eligibility for Social Security Benefits who are legally entitled to receive them, but also keep them from obtaining other federal and state benefits. Since all applicants for SSI benefits must also pass a means test, SSA is necessarily dealing with people who are already on the economic margins of society. Recently, SSA has developed a number of new programs designed to encourage adults with mental retardation to obtain their first job or to return to work. These programs are at an early stage of implementation, and their effectiveness has yet to be determined. The agency appears to be balancing its role as a safety net with an attempt to encourage recipients to work. In the committee’s view, this balance is the right one to strike. The committee makes the following recommendation to assist SSA and disability benefit recipients in achieving this balance. Recommendation: The Social Security Administration should remove disincentives for people with mental retardation to seek employment by: Considering individuals with mental retardation to be presumptively re-eligible for benefits throughout their lives, if they have previously received benefits, subsequently secured gainful employment, and then lost that employment. Encouraging the use of work incentive programs for people with mental retardation, with appropriate and necessary protections of each program’s role as a safety net for income support. Permitting individuals with mental retardation to retain eligibility for Medicaid independent of their employment status. RESEARCH Finally, in reviewing the literature on mental retardation and related areas, the committee has identified a number of promising research opportunities that would help to clarify unaddressed or incom-

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Mental Retardation: Determining Eligibility for Social Security Benefits pletely answered questions. We are also aware that SSA is expecting to receive momentarily from research organizations like RAND the results of various analyses it has commissioned, which may contribute to changes in its policies on disability determination. In addition, the American Association on Mental Retardation has undertaken deliberations that may soon result in changes to its 1992 definition of mental retardation and its constructs. These and other activities highlight the active nature of this field in both research and practice. The committee’s recommendation for needed research is intended for SSA and other federal agencies that work on education, vocational training, health and mental health, and disability-related issues. Recommendation: Federal agencies, including the Social Security Administration, should fund studies to evaluate the accuracy of program eligibility decisions and foster research on adults with mental retardation, including their adaptive behavior. The research funding should include investigations of multimethod techniques for the assessment of job-related skills, social adaptation, health, and well-being. In addition, relevant epidemiological studies and research on the accuracy of the diagnosis of mild mental retardation are essential to further inform policy and decision making. SSA should evaluate the consequences of implementing the committee’s recommendations in the context of public policies and economic conditions, reporting findings to the public within five years. Since improved accuracy in eligibility determination depends more on improved measures of the key dimensions of mental retardation than on adjusting cutoff scores, the committee recommends research on improving measures, especially adaptive behavior assessment, and on methods to combine information on adaptive and intellectual functioning in making

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Mental Retardation: Determining Eligibility for Social Security Benefits eligibility decisions based on a diagnosis of mental retardation. SSA should make available for use by legitimate researchers tapes of Supplemental Security Income and Disability Insurance program utilization, comparable to public use tapes available for Medicaid program utilization. SSA should link its data on individual benefit awards to other agency data on health care and service costs for those same beneficiaries. SSA should examine data on eligibility determination procedures across its 10 districts, in order to discover if implementation of classification policies is consistent or varies regionally.