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Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
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Chapter 1
Introduction

Current estimates suggest that between 1 and 3 percent of people living in the United States will receive a diagnosis of mental retardation. This report assesses the process used by the U.S. Social Security Administration (SSA) to identify individuals with cognitive limitations who experience significant problems in their ability to perform work and may therefore be in need of governmental support. It evaluates the existing disability determination process in the context of current scientific knowledge and clinical practice. Mental retardation, a condition characterized by deficits in intellectual capabilities and adaptive behavior, can be particularly difficult to diagnose in the mild range of the disability.

SOCIAL SECURITY ADMINISTRATION DISABILITY PROGRAMS

SSA administers two disability programs that provide income and medical benefits to individuals who are either unable to work or to

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×

function as expected given their age because of disability. The Disability Insurance (DI) program, which operates under Title II of the Social Security Act, provides monetary payments to formerly employed individuals who have contributed to the Social Security trust fund through Social Security tax on earnings. Certain classes of dependents of insured individuals are also eligible for DI benefits. The Supplemental Security Income (SSI) program, which operates under Title XVI of the Social Security Act, provides payments to individuals (including children younger than 18 years of age) with a disability who have limited income and other resources. Such a person does not have to have been employed or a contributor to Social Security to be eligible for SSI benefits, although a means test is applied to both income and assets.

Disability is defined similarly for both the DI and SSI programs. For all persons applying under the DI program and for adults applying under the SSI program, disability is defined as “the inability to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment(s) which can be expected to result in death or which has lasted or can be expected to last for a continuous period of not less than 12 months” (Social Security Administration, 2002, p. 4). Standards are different for children younger than age 18. For this group, disability is defined as having a “medically determinable” physical or mental impairment, or combination of impairments that cause “marked and severe functional limitations.” The impairment must be expected to lead to death or to be present for a continuous 12-month period. A medically determinable impairment is one resulting from anatomical, physiological, or psychological abnormalities that can be established by medical evidence that includes signs, symptoms, and laboratory findings; findings must go beyond the individual’s subjective complaints.

Disability Determination Process

The application process for DI and SSI benefits can be a long and complicated one. Individuals (or their parents or guardians) may file for disability benefits by telephone, mail, or by visiting the nearest So-

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×

cial Security Office. The nearest Social Security Office can be identified by calling the toll free number (1-800-772-1213; 1-800-325-0778 for TTY calls). An individual can also call the toll free number and make arrangements to complete an application by telephone. SSA will then set up a time for the local Social Security Office to contact the individual and take the application over the telephone. SSA’s website (www.ssa.gov) has helpful information about qualification criteria and procedures for filing disability benefits.

The in-person or telephone interview will be conducted by a claims representative of SSA. The claims representative will determine if the technical aspects of disability eligibility or entitlement are met. If the individual is eligible for benefits under the Title II program, or the Title XVI program, or both programs, the medical and vocational material is then forwarded to the state disability determination services (DDS) in the applicant’s state. Medical information can include telephone numbers of doctors, hospitals, clinics, and institutions in which the person received treatment, as well as the dates of treatment; names of all medications currently being prescribed; medical records; and laboratory and test results. Vocational information can include summaries of previous work experiences and locations and a copy of a W-2 form.

Trained disability examiners and medical consultants, who will review all the pertinent information and make the determination of disability, staff the DDS. DDS staff may require additional information in making their determinations—for example, information directly from the applicant’s treating clinician. DDS staff may require the applicant to undergo an examination conducted by SSA-hired consultative examiners.

DDS staff make the determination of disability based on the questions presented in Box 1-1.

The box outlines the five-step process for adults and the three-step process for children used to evaluate applicants for disability benefits. Beyond the stepwise determination process, there are several levels of appeal. There can be a hearing before an administrative law judge at SSA, review by SSA’s Appeals Council, and ultimately review

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×

Box 1-1 Sequential Evaluation Process for Disability Insurance and Social Security Income Benefits

Social Security regulations outline the sequential evaluation process used to evaluate applicants for disability benefits. Program rules further note that when an applicant is deemed not disabled at any one step, an evaluation under the subsequent steps is unnecessary.

For adults applying under the DI or SSI program, there is a five-step sequential evaluation process guided by the following questions:

  • Step 1. Are you working? If you are working at the level of substantial gainful activity (defined as more than $740 per month in 2001), SSA will find that you are not disabled regardless of your medical condition or your age, education and work experience.

  • Step 2. Is your impairment severe? A severe impairment(s) is defined as one that significantly limits physical or mental ability to do basic work activities. If your impairment(s) is severe, SSA proceeds to the next step.

  • Step 3. Does your impairment(s) meet or medically equal a listed impairment? If so, and it meets the durational requirement, you will be found disabled. When an impairment(s) is not in the listings, SSA must decide whether it equals the severity of a listed condition. If the impairment(s) is severe but does not meet or equal a listing, SSA proceeds to the next step.

  • Step 4. Can you perform past relevant work? If your impairment(s) prevents you from performing the physical and mental

by the federal courts. Clearly, both the stepwise determination process and the appeals process involve the use of objective and subjective indicators, as well as many judgments on the part of those making the determinations. Such a process inevitably results in errors, which can be of two types: they can incorrectly exclude someone who is legally entitled to benefits or can incorrectly result in benefits for someone who is not entitled to them. Since both types of errors are costly to the individual and to society, it is important to identify the sources of error and to minimize them. Some are inherent in the criteria for disability determination and the assessment instruments used to determine whether the client meets them.

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×

demands of work that you have done in the past, SSA proceeds to the next step.

  • Step 5. Can you do other types of work? SSA determines whether you can do work other than previous relevant work, considering your residual functional capacity, age, education, and past work. If you cannot, SSA will find you disabled.

For children and adolescents applying under the SSI program, there is a separate three-step sequential process. This process is guided by the following questions:

  • Step 1. Are you working? If you are working at the level of substantial gainful activity (defined as more than $740 per month in 2001), SSA will find that you are not disabled regardless of your medical condition or your age, education, and work experience.

  • Step 2. Do you have a medically determinable impairment(s) that is severe? Is you do not have a medically determinable impairment, or your impairment(s) is one that causes no more than minimal functional limitations, SSA will find that you do not have a severe impairment, and are, therefore, not disabled. If the impairment(s) is severe, SSA proceeds to the next step.

  • Step 3. Does your impairment(s) meet, medically equal, or functionally equal the listings? If it does, and also meets the durational requirement, SSA will find you disabled. If it does not, SSA will find that you are not disabled.

Criteria for Mental Retardation

SSA disability determination for mental retardation requires that the individual have “significantly sub-average general intellectual functioning with deficits in adaptive functioning initially manifested during the developmental period; i.e., the evidence demonstrates or supports onset of the impairment before age 22” (Social Security Administration, 2002, p. 76). Children must also have significantly subaverage general intellectual functioning with deficits in adaptive behavior. Since they are children and under age 22, such findings will have manifested during the developmental period. The Listing of Im-

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×

pairments, which specifies medical criteria and associated diagnoses, includes separate criteria for adults and for children and adolescents with mental retardation.

Listing 12.05 of Part A lays out criteria for mental retardation; it is closely paraphrased here. In order to be found eligible for benefits due to mental retardation, adults must be mentally retarded as defined above, and must meet one of four requirements:

  • mental incapacity as evidenced by dependence upon others for personal needs (e.g., toileting, eating, dressing, etc.) and an inability to follow simple directions that is so severe that standardized measures of intellectual functioning cannot be administered;

  • valid verbal IQ (VIQ), performance IQ (PIQ), or full-scale IQ (FSIQ) equal to 59 or less;

  • valid VIQ, PIQ, or FSIQ between 60 and 70, and a separate physical or mental impairment that imposes an additional and significant limitation on work-related functioning; or

  • valid VIQ, PIQ, or FSIQ between 60 and 70, along with at least two of the following: (a) marked restriction of activities of daily living, (b) marked difficulties maintaining social functioning, (c) deficiencies of concentration, persistence or pace that results in problems completing tasks in a timely manner, or (d) repeated episodes of decompensation.

Satisfaction of any one of these four criteria in an individual who has mental retardation meets the step 3 criterion of SSA’s determination process; i.e., that the individual has a prima facie case of disability that results in an inability to work.

Separate determination criteria have been developed for children and adolescents, which recognize the different processes and effects that mental disorders have on their functioning. Determination criteria for children are further subdivided by age and associated developmental expectations. Criteria are provided for infants and toddlers (e.g., between ages 1 and 3) and three age groups of children and adolescents (e.g., ages 3 to 6, 6 to 12, and 12 to 18). These age criteria are

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×

designed to assess the severity of the disability’s impact on the child’s or adolescent’s functioning, with benefits provided for conditions that cause “marked” restrictions, defined as “more than moderate but less than extreme.” On standardized tests, a score that is “two standard deviations below the mean for the test” is evidence of a marked restriction. A score that is three standard deviations below the mean on a standardized test is evidence of an extreme limitation.

Medical criteria for evaluating children with mental retardation are described in Listing 112.05. Like the definition for adults, mental retardation in children for SSA disability purposes is characterized by significantly subaverage general intellectual functioning, with deficits in adaptive functioning. The Listing, again in paraphrase, includes six criteria for assessing severity of the condition:

  • deficiencies in motor development, cognitive/communicative functioning, or social functioning for infants and toddlers; and for children and adolescents, deficiencies in at least two areas that include cognitive/communicative functioning, social functioning, personal functioning, or deficiencies in concentration, persistence, or pace that result in failure to complete tasks in a timely manner;

  • a dependence on others for personal needs that is grossly in excess of age expectations, and an inability to follow directions that is so severe that standardized tests cannot be administered;

  • valid VIQ, PIQ, or FSIQ of 59 or below;

  • valid VIQ, PIQ, or FSIQ between 60 and 70 and a coexisting physical or other mental disorder that significantly impairs functioning;

  • valid VIQ, PIQ, or FSIQ between 60 and 70 and, for infants and toddlers, the failure to attain development expectations for motor, cognitive/communication, and social functioning that is consistent with other children no more than two-thirds of their chronological age; for older children and adolescents, problems with cognitive/communicative function, social function, personal function, or problems with concentration, persistence, or pace; or

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×
  • failure of older infants and toddlers to attain motor, cognitive/ communicative, and social milestones of children no more than two-thirds of their chronological age and another physical or other mental impairment that significantly impairs functioning; for older children and adolescents, problems with cognitive/communicative, social, or personal function or deficiencies in concentration, persistence, or pace that result in the failure to complete tasks in a timely manner and an additional physical or other mental impairment that significantly impairs functioning.

HISTORY OF MENTAL RETARDATION DEFINITIONS

The definition of mental retardation currently used by SSA differs from that used by other professional and health-related organizations. The concept of mental retardation, particularly a recognition that some portion of the population has cognitive deficits that significantly interfere with functioning, is an old one, although the ways in which this has been defined and measured have changed over time. Scheerenberger (1983) reports descriptions of the condition dating from 1500 B.C. in Egypt, in which disabilities of the mind and body due to brain damage were described.

Early definitions of the condition recognized differences in cognition that were associated with impaired functioning. In 1845, Esquirol (quoted in Scheerenberger, 1983) divided mental retardation into two primary categories based on performance on speech and language tasks. Seguin (1866) identified a severe defect in moral development as the primary characteristic of mental retardation.

According to Sheerenberger (1983), the major concepts common to current definitions of mental retardation were being used in the United States by 1900. These include onset during the developmental period (i.e., before age 22), intellectual deficits, and problems coping with the demands of everyday life. In its 1910 classification scheme, the progenitor of today’s American Association on Mental Retardation (AAMR) (previously called the Association of Medical Officers of American Institutions for Idiotic and Feeble-minded Persons and the

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×

American Association on Mental Deficiency) issued its first formal definition of mental retardation. AAMR defined persons with mental retardation as being feeble-minded, with development arrested at an early age or as evidenced by an inability to manage the demands of daily life or to keep up with peers (Committee on Classification of Feeble-Minded, 1910). Mental retardation was further divided into three levels of impairment: “idiots” had their development arrested at the level of a 2-year-old; “imbeciles” were at the developmental level of a 2- to 7-year-old; and “morons” were at the development of a 7- to 12-year-old.

Subsequent to the adoption of this definition, the field disagreed over whether mental retardation was a constitutional condition or one based on deficits in social competence (Biasini et al., 1999). Edgar Doll, for instance, proposed that mental retardation was a condition of genetic origin that resulted in social incompetence and arrested development (Doll, 1936a). He believed the condition was incurable. In contrast, Kuhlman (1920) proposed that the condition resulted from a subnormal rate of development, suggesting that it was a result of social functioning deficits rather than genetic conditions. Despite these differences in definition, however, they all focused on the inability to perform common behaviors, delays in social development, and low intelligence (Yepsen, 1941).

The 1959 AAMR definition was the first to integrate formally the measurement of intellectual capabilities and adaptive behavior functioning. This definition defined mental retardation as “subaverage general intellectual functioning which originates in the developmental period and is associated with impairment in adaptive behavior” (Jacobson, 1999). Subaverage intellectual functioning was defined as an IQ of 85 or less, with the developmental period extending only up to age 16. Deficits in adaptive behavior were a required part of the definition of the condition, even though there were no formal measures of the construct. AAMR recommended use of the Vineland Social Maturity Scale (Doll, 1953), with a subjective interpretation to be made by the evaluating clinician. A five-level classification scheme was also included for borderline (IQ 67-85), mild (IQ 50-66), moder-

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×

ate (IQ 33-49), severe (IQ 16-32), and profound (IQ <16) levels of retardation.

AAMR changed its definition in 1973, partly in response to concern about the inappropriate overidentification of minority students as mentally retarded. The new definition eliminated the classification of borderline retardation, and changed the upper criterion of scores on intelligence measures from 85 to 70 or below (Grossman, 1973). The result was a significant reduction in the numbers of children eligible for special school services and governmental supports. Levels of retardation were also redefined slightly.

AAMR’s definition was revised again in 1977. This change suggested that IQs in the range of 70 to 75 might also be indicative of mental retardation if there were also significant deficits in adaptive behavior (Grossman, 1977). This change took into consideration the standard error of measurement on most tests of intelligence. In its most recent definition, adopted in 1992, AAMR has done away with the levels of retardation (American Association on Mental Retardation, 1992). The organization has also provided a list of 10 adaptive skill areas, with deficits in at least 2 of them required for a diagnosis of mental retardation. This current definition is discussed in more detail below.

The American Psychiatric Association, in its Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), melded the 1977 and 1992 AAMR definitions, retaining the severity levels from 1972 and adopting a list of adaptive behavior areas similar to those chosen by AAMR in 1992. The DSM-IV also kept the upper limit of intelligence at equal to or less than 70.

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 experience significant problems in their ability to perform work and may therefore be in need of governmental support.

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×

PREVALENCE OF MENTAL RETARDATION

In the General Population

There are widely disparate prevalence estimates of mental retardation in the U.S. population. Different studies report different rates depending on the definitions used, methods of diagnosis, and the particular population studied. For instance, the DSM-IV estimates the prevalence of mental retardation at 1 percent, although the basis for this number is not provided (American Psychiatric Association, 1994). This estimate is similar to that provided by other researchers (Hodapp & Dykens, 1996). Baroff (1991), using empirical sampling, estimates that 0.9 percent of the U.S. population can be presumed to have mental retardation. In a review of epidemiological studies, McClaren and Bryson (1987) report the prevalence of mental retardation at 1.25 percent, based on total population screening. Among school-age children, the U.S. Department of Education (1994) reports that prevalence estimates provided by different states in determining eligibility for special educational services ranged from 0.3 to 2.5 percent. In contrast, the U.S. surgeon general has estimated that some 7.5 million persons living in the United States have a diagnosis of mental retardation, representing almost 3 percent of the population.

The Centers for Disease Control and Prevention is conducting a longitudinal study called the Metropolitan Atlanta Developmental Disabilities Surveillance Program (MADDSP), which monitors the prevalence of developmental disabilities, including mental retardation, among children 3 to 10 years of age in the metropolitan Atlanta region (Boyle et al., 1996). The study used the definition of mental retardation listed in the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9) (World Health Organization, 1988), which includes severity ratings for mild, moderate, severe, and profound levels of retardation. Findings from the MADDSP indicate an overall prevalence of 8.7 per 1,000 children 3 to 10 years of age in Atlanta. Approximately two-thirds of all cases of retardation were of mild severity. Prevalence of mental retardation varied by age, ranging

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×

from 5.2/1,000 for children 3 to 4 years of age to 12.3/1,000 for children 9 to 10 years of age. Increases in prevalence were more likely to occur for children in the mild and moderate ranges of retardation, rather than in the severe and profound ranges.

These rates for children are similar to those reported in analyses of the National Health Interview Survey. Again, using the ICD-9 definition of mental retardation, Halfon and Newacheck (1999) reported unadjusted prevalence rates for mental retardation at 10.5/1,000 for children younger than 18. Analyses further indicated that the prevalence of mental retardation increased with age, ranging from 2.0/1,000 cases for children younger than 6, to 14.7/1,000 cases for children ages 6 to 12, and 15.7/1,000 cases for youth ages 12 to 17. The prevalence of mental retardation was also higher for males (13.0/1,000) than females (7.9/1,000).

Among different racial/ethnic groups, the prevalence of mental retardation was higher among black youth (16.2/1,000) than white (9.8/1,000), Hispanic (9.0/1,000) and other (6.4/1,000) youth. Prevalence rates are higher in some racial/ethnic groups partly because the responses to the National Health Interview Survey are provided by parents, who may have cultural reasons for concealing their child’s cognitive disability. The correlation of low socioeconomic status and mental retardation is very high (see Chapter 2), and poverty rates are very high among black and Hispanic youth.

These prevalence estimates are vastly different, ranging from a low of 1 percent to a high of almost 3 percent. It is likely that the actual number of individuals with mental retardation ranges between 1 and 3 percent. This suggests that between 2.8 million and 7.5 million individuals could be diagnosed as having mental retardation.

In the Social Security System

Individuals with a diagnosis of mental retardation constitute a significant number of all recipients of SSA disability benefits. Data from SSA’s Annual Statistical Supplement (2001a) indicate that as of December 2000, 567,151 persons with a diagnosis of mental retardation

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×

were receiving DI benefits, including 257,601 workers, 299,925 children age 18 or older, and 9,625 widows or widowers. Individuals classified as mentally retarded represented 10 percent of all workers with disabilities.

The SSI program has similarly high numbers of recipients with mental retardation. Among children receiving SSI benefits in December 2000, individuals with a mental retardation diagnosis constituted the largest diagnostic group at 32.8 percent (261,200 individuals). Consistent with other epidemiological data, the number of boys (162,230) outnumbered the number of girls (98,880) among children classified as having mental retardation (Social Security Administration, 2001b).

Data from December 2000 also highlight high numbers of adult recipients with mental retardation among SSI beneficiaries (Social Security Administration, 2001a). Among adult SSI recipients, individuals with mental retardation constituted 25.7 percent of all beneficiaries, representing the second largest diagnostic group of recipients (“all other mental disorders” was the largest at 34.4 percent). Males (52.5 percent) outnumbered females (47.5 percent) among SSI recipients with mental retardation.

ISSUES THAT PROMPTED THE CURRENT STUDY

The current study was designed to assess SSA’s disability determination process for mental retardation. The committee was asked to examine new scientific opportunities and associated practice techniques to improve the current determination process. In addition, the committee has been asked to suggest new procedures to respond to these developments. Finally, this study will identify promising research opportunities that might help to clarify unaddressed or incompletely answered questions. SSA is most concerned about accurately diagnosing mental retardation among individuals in the mild range of retardation.

This report draws on recent research advances in the areas of cognition and learning, new information about the neural processes that

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×

occur during thinking and learning, and new knowledge about development of learned competencies, such as social skills and practical skills for everyday living. Furthermore, research from decision sciences has been examined to inform SSA’s policy making. This study was prompted by a number of issues, including:

  • the adequacy of SSA’s definition of mental retardation,

  • questions about intellectual assessment,

  • issues raised by the assessment of adaptive behavior,

  • thinking about how to combine data from intellectual and adaptive behavior assessments, particularly in the mild range of mental retardation, to accurately diagnose the condition, and

  • issues related to distinguishing mental retardation from other diagnoses, particularly for children and adolescents.

Public Policy Implications

The diagnosis of mental retardation, as well as the receipt of benefits, has associated public policy implications. These policy issues relate to the context in which the program operates, as well as the impact of benefit receipt. Recipients get money to help with income maintenance, but they also get health care coverage through Medicaid. This health care coverage allows individuals with chronic medical conditions to receive needed treatment. In response to a number of issues, SSA changed the nature of its definitions of mental retardation and consequently the number of individuals receiving benefits. Any review of current practice has to consider that additional changes, while well meaning, may have negative effects on beneficiaries and the disability program itself. The committee has included an analysis of these issues in its assessment of the current determination system.

Adequacy of the SSA Definition

SSA’s definition of mental retardation rests on subaverage intellectual functioning, either alone or in combination with other disabilities

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×

or functional impairments. The impairment must be present before the age of 22, although the diagnosis may be made at any time. This definition of mental retardation differs from that of several other organizations, including the American Psychiatric Association in its DSM-IV, the American Association of Mental Retardation, the World Health Organization in its International Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10), and Division 33 (Mental Retardation and Developmental Disabilities) of the American Psychological Association.

DSM-IV defines mental retardation as significantly subaverage intellectual functioning (i.e., IQ no higher than approximately two standard deviations below the mean), which is accompanied by significant limitations in adaptive functioning in at least two of the following areas: communication, functional academic skills, health, home living, leisure, safety, self-care, self-direction, social/interpersonal skills, use of community resources, and work. Onset of these conditions must occur before age 18. The condition is further divided into four levels of retardation based on IQ, which include mild mental retardation (IQ between 50-55 and 70), moderate mental retardation (IQ between 35-40 and 50-55), severe mental retardation (IQ between 20-25 and 35-40), and profound mental retardation (IQ below 20 or 25) (American Psychiatric Association, 1994).

For AAMR, mental retardation is defined by substantial limitations in present functioning. It is defined as subaverage intellectual functioning that exists concurrently with deficits in two or more of the following adaptive skill areas: communication, self-care, home living, social skills, community use, self-direction, health and safety, functional academics, leisure, and work. The condition has to be manifested before age 18. AAMR further classifies mental retardation based on the nature and level of support needed by the individual, which can be intermittent, limited, extensive, or pervasive (American Association on Mental Retardation, 1992). These levels of support are not necessarily commensurate with the levels of retardation specified in the DSM-IV.

The World Health Organization (WHO), in its ICD-10, defines mental retardation as a “condition of arrested or incomplete develop-

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×

ment of the mind, which is especially characterized by impairment of skills manifested during the developmental period, which contribute to the overall level of intelligence, i.e., cognitive, language, motor, and social abilities.” Guidelines suggest that an IQ of less than 70 is indicative of mental retardation. ICD-10 further suggests the use of culturally relevant, standardized measures of social maturity and adaptation for assessing functional abilities. No guidelines are provided, however, on cutoff scores for adaptive behavior deficits. ICD-10 allows for assigning a diagnosis of mental retardation when an individual has both mental retardation and a coexisting mental or physical disorder.

Division 33 of the American Psychological Association has defined mental retardation as “(a) significant limitations in general intellectual functioning; (b) significant limitations in adaptive functioning, which exist concurrently; and (c) onset of intellectual and adaptive limitations before the age of 22 years” (Jacobson & Mulick, 1996). Significant limitations for both intellectual and adaptive functioning are defined as two or more standard deviations below the population mean, using standardized assessment tools.

These definitions differ from those offered by SSA on a number of dimensions. The most significant differences are focused on the age of onset (e.g., 18 versus 22 years of age) and the nature of adaptive functioning deficits and how they are to be measured. WHO and Division 33 advocate the use of a standardized measure of adaptive behavior functioning, while AAMR and the American Psychiatric Association allow for descriptors of functional deficits across different domains. Even with this latter approach, however, the number of areas in which functional limitations must be present also differs. The American Psychiatric Association allows for deficits in at least 2 of their 11 areas, and AAMR specifies deficits in at least 2 of its 10 adaptive skill areas. In contrast, SSA does not specify the number of areas that need to be deficient, relying instead on “marked” restriction of activities of daily living and “marked” difficulties with social functioning. It is worth noting again that SSA uses its definition of mental retardation not for diagnostic purposes, but rather to determine legal eligibility for its ben-

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×

efit programs, in order to ensure that federal resources are used justly and correctly.

Intellectual Functioning and Its Assessment

SSA is similar to the other organizations in the level of intellectual impairment required to be present before a diagnosis of mental retardation can be assigned (i.e., IQ no higher than two standard deviations below the mean). For the other groups, however, that score has to be on the summary score attained on the intellectual functioning measure (e.g., equivalent to Wechsler FSIQ). SSA will also accept part scores from individually administered IQ tests, and specifically mentions Wechsler part scores as examples (e.g., VIQ, PIQ) in its regulations.

While SSA encourages the use of any standardized tests to determine intellectual and adaptive behavior functioning, it does not require these tests. It inadvertently gives preference to the Wechsler tests in its regulations by mentioning that the lowest of the overall summary score (FSIQ) and the two part scores (VIQ and PIQ) may be used in determining intellectual functioning. This not only cements a disparity among measures, without a solid empirical or policy basis, but also begs the question of whether one of these three scores provides the best relevant information. For instance, the FSIQ has higher reliability and validity coefficients than the two part scores. SSA needs to know if current practice and science support a policy of adjudicating on the basis of the lowest of multiple IQs; i.e., FSIQ, VIQ, or PIQ.

SSA further seeks to determine if its cutoff scores of 59 or less and 60 through 70 are also consistent with the current scientific literature on diagnosing mental retardation. The stringent upper limit fails to take into consideration the standard of error of measurement characteristic of all IQ tests. These basic assessment issues are further compounded when tests are administered to a culturally and linguistically diverse population. In some cases, instruments may not be available in a person’s native language, or norming procedures may make the instrument inappropriate for use with some culturally and linguistically defined subpopulations.

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
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It is important to know whether the major instruments in the field, such as the Wechsler scales and Stanford-Binet Test of Intelligence, adequately assess intelligence in a given case. If they do not, clinically acceptable and programmatically workable alternative instruments should be explored. This may entail identifying other instruments (including nonverbal intelligence assessment instruments as well as instruments available in languages other than English) that have sufficient reliability and validity to adequately diagnose mental retardation. Of course, any additional instruments identified should have the potential for wide use in clinical practice settings.

A number of research areas have produced reliable findings that are relevant and ready for implementation in practice. Advances in the assessment of developmental functioning have expanded the examination of intelligence from a dependence on verbal and performance intelligence scores to a broader view that incorporates measures of process as well as product. Multiple components that comprise intellectual functioning can now be more easily separated, for example, attentional processes, computational processes, problem-solving skills, and performance processes.

In the area of developmental assessment, standardized preschool measures of competence (Bayley, 1993) are required to assess multiple domains of functioning. These include fine motor, gross motor, cognitive, communication, and social skills. Impairment judgments based only on verbal and performance IQs may not reflect current intelligence testing practices for preschool children. The committee was charged with determining if other instruments better assess young children’s intellectual functioning.

Adaptive Behavior Functioning and Its Assessment

For individuals with an intelligence score greater than 59, SSA requires documentation of deficits in adaptive behavior and functioning in order for a classification of mental retardation to be made, as long as no other serious medical condition is present. This may include the results of standardized tests (e.g., Scales of Independent-

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×

Behavior-Revised, Vineland Adaptive Behavior Scales) or descriptions from parents, teachers, or treating clinicians. The use of either descriptive evidence or standardized test results seems to reflect variations in practice throughout the field of mental retardation. AAMR and the American Psychiatric Association both allow for behavioral descriptors of adaptive behavior in order to diagnose mental retardation. Division 33 of the American Psychological Association and WHO, however, suggest that results from standardized psychological assessments should be used (Jacobson & Mulick, 1996).

SSA has asked the committee for advice on how best to assess adaptive behavior for eligibility determination and award of benefits. With its current practice, SSA may frequently receive different kinds of information from different sources. The lack of standardization in the assessment of adaptive behavior may lead to a number of difficulties. Currently, claims may be adjudicated on the basis of different kinds of information, and trained lay examiners have the responsibility of combining data from different sources to try and sift out any evidence of deficits in adaptive behavior functioning, working in concert with medical consultants. The result may be inconsistent decision making and a time-consuming determination process.

Other important issues are how well major current measures of communicative, social, personal, motor, and community living skills identify and quantify deficits in adaptive behavior, and how well they meet current standards of reliability and validity. The committee explored alternative approaches that are clinically acceptable and programmatically workable, as well as measures that are currently used but are not satisfactory.

Combining IQ and Adaptive Functioning Data

Describing the nature of behavioral deficits becomes most needed—and most problematic—for individuals whose IQ is close to 70. Currently, SSA combines standardized IQ data with varying kinds of information on adaptive functioning. For adults, disability examiners consider adjustment in occupational and social settings; self-care is

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
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also a focus. For children, adjustment, including meeting developmental expectations, is a focus. There are, however, no guidelines about how to consistently combine these two kinds of information.

SSA is interested in the unique contribution each type of measure makes to the analysis of the adjustment of the individual to his or her world. A subset of this issue is the particular contribution of each to the evaluation and diagnosis of mental retardation in borderline situations, i.e., in cases in which the obtained IQ hovers near 70.

Current SSA practices allow a wide role for the qualitative evaluation of performance. Advances in the study of adaptive functioning have provided a more differentiated view of individual social and personal competence. Reviewing current thinking on the multiple dimensions of adaptive functioning could produce new models for such assessment or improve the utility of older assessments by identifying or updating appropriate cutoff scores for disability, or it may point to desirable and justified alterations of functional areas that are the focus of review in the eligibility determination process. The committee has reviewed the practice of allowing qualitative assessments of adaptive functioning, as well as instruments that provide standardized evaluations of adaptive functioning.

Differential Diagnosis

The issue of better differentiating mental retardation from other disorders that may have similar behavioral and cognitive manifestations—called differential diagnosis—is considered last. SSA has had particular difficulty distinguishing mental retardation from other disorders in children and adolescents. The Sullivan v. Zebley decision in 1990, in which the U.S. Supreme Court relaxed the criteria whereby children became eligible for SSI benefits; changes in determination criteria secondary to the Personal Responsibility and Work Opportunity Reconciliation Act of 1996; and the Balanced Budget Act of 1997 have all resulted in criticisms of SSA’s attempts to distinguish mental retardation from other cognitive disabilities.

A number of conditions, such as autism, learning disabilities, bor-

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×

derline intellectual functioning, and some organic mental disorders, like traumatic brain injury, are associated with features that overlap with those seen in mental retardation. In addition, some genetic and behavioral disorders share features with mental retardation.

The committee has reviewed these other diagnoses, evaluating the signs and symptoms that are similar to those exhibited by individuals diagnosed with mental retardation, and is providing SSA with suggestions for better distinguishing these cognitive, genetic, and behavioral disorders from mental retardation.

Additional Research Needs

Finally, the process of evaluating scientific evidence generally reviews an area in great detail. The committee summarizes here its finding with respect to additional research that might improve the assessment and diagnosis of mental retardation. It is important to know what research needs to be conducted so that individuals with mental retardation can be better identified and can therefore have access to more appropriate services from education, health, and social service agencies. This question is designed to address the long-term needs of SSA and disability benefit recipients.

STUDY APPROACH

The committee and staff cast a wide net in examining the literature on mental retardation and its assessment. This approach was designed to gather information from a wide range of sources and assess the strengths and weaknesses of various pieces of evidence, with a goal of finding convergence of information from descriptive and inferential data and theoretical and conceptual frameworks.

Literature searches were conducted in peer-reviewed journals; technical manuals on intelligence and adaptive behavior measures were reviewed; papers were commissioned from experts on a number of topics central to the committee’s work; and feedback was solicited from professional practice, advocacy, and other relevant groups. Members

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×

also reviewed technical and policy literature from SSA and other government agencies to get a better sense of the disability programs and benefits provided to individuals with mental retardation. To better understand the practical and policy implications of proposed recommendations on benefit receipt, the committee conducted statistical procedures called Monte Carlo simulations to examine the consequences of altering the criteria for scores on intelligence and adaptive behavior measures. In all of its review work, the committee focused in particular on the area of mild mental retardation, which is most problematic.

ORGANIZATION AND SCOPE OF THE REPORT

This report is focused on specifying criteria for the determination of mental retardation for SSI/DI eligibility purposes. It examines the contextual issues affecting SSA disability benefit programs, with Committee members recognizing that any evaluation of the current determination process for mental retardation is likely to have public policy effects. These effects are discussed in Chapter 2. SSA’s charge to the committee posed several questions. The first, do current IQ tests adequately reflect widely accepted concepts of intelligence, is discussed in Chapter 3. The second asks how adaptive functioning is best defined and assessed; the committee’s detailed response is in Chapter 4. SSA also asked about the relationship between measures of intelligence and adaptive behavior, which is covered in Chapter 5. Chapter 6, on differential diagnosis, explains how the conditions that share signs and symptoms with mental retardation are best distinguished from it. Suggestions for additional research that might shed light on any unaddressed or incompletely resolved issues in the field of mental retardation are mentioned throughout the text and are summarized in Chapter 5.

In focusing on specifying criteria for the determination of mental retardation for SSI/DI eligibility purposes, this report speaks to the intellectual and adaptive behavior criteria that should be used in making these determinations. The committee’s findings, conclusions, and

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
×

recommendations address initial eligibility determinations, that is, individuals who are first applying for disability benefits. For this reason, the committee has reviewed information that applies to all classes of potential beneficiaries, including children and adolescents and adults.

The committee has not explicitly addressed eligibility redetermination, the process of periodically recertifying eligibility for SSA benefits. The time interval for conducting redeterminations varies according to the medical condition. In general, they are scheduled every 7 years for individuals with conditions unlikely to change; every 3 years for conditions amenable to improvement; and as soon as 18 months for conditions likely to improve in the near future. Redeterminations for mental retardation are conducted every 7 years. Committee members view the standards for intellectual functioning and adaptive behavior assessment outlined in this report as applicable to the redetermination process as well.

Suggested Citation:"1. Introduction." National Research Council. 2002. Mental Retardation: Determining Eligibility for Social Security Benefits. Washington, DC: The National Academies Press. doi: 10.17226/10295.
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Current estimates suggest that between one and three percent of people living in the United States will receive a diagnosis of mental retardation. Mental retardation, a condition characterized by deficits in intellectual capabilities and adaptive behavior, can be particularly hard to diagnose in the mild range of the disability. The U.S. Social Security Administration (SSA) provides income support and medical benefits to individuals with cognitive limitations who experience significant problems in their ability to perform work and may therefore be in need of governmental support. Addressing the concern that SSA’s current procedures are consistent with current scientific and professional practices, this book evaluates the process used by SSA to determine eligibility for these benefits. It examines the adequacy of the SSA definition of mental retardation and its current procedures for assessing intellectual capabilities, discusses adaptive behavior and its assessment, advises on ways to combine intellectual and adaptive assessment to provide a complete profile of an individual's capabilities, and clarifies ways to differentiate mental retardation from other conditions.

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