In 1983, the American Association on Mental Retardation (AAMR) defined mental retardation as “significantly sub-average general intellectual functioning resulting in or associated with concurrent impairments in adaptive behavior and manifested during the developmental period.”⁴ In its earlier 1973 report, the AAMR defined “significantly sub-average general intellectual functioning” as performance on psychometric tests that is more than two standard deviations below the mean. Thus, on the Stanford-Binet IQ test, a score below 67 would classify a person as mentally retarded. In 1973, the AAMR also classified the severity
of retardation on the basis of IQ scores: mild (52-67), moderate (36-51), severe (20-35), and profound (19 and below).⁵

In its revised report of 1983, the AAMR chose to redefine the boundary separating normal intelligence from mental retardation at an IQ of 70. This score could be extended to as high as 75 in those patients for whom the reliability of the psychometric instrument was questionable, the patient’s behavior was impaired, or the clinician deemed that this behavior did not stem from a deficit in reasoning and judgment.⁶ In 1992, the AAMR again slightly revised its definition of mental retardation but retained the original essential criteria of “significantly subaverage intellectual functioning” with “limitations in … adaptive skill areas.”⁷

The AAMR defined “adaptive behavior” as “the effectiveness or degree with which the individual meets the standards of personal independence and social responsibility of his age and cultural group.” Measurement of adaptive behavior during infancy and early childhood focused on the development of sensorimotor skills, communication skills, self-help skills, and socialization. During later childhood, adaptive behavior was reflected in academic skills, reasoning and judgment, and socialization. In adolescence and adulthood, performance in vocational and social arenas was the most important measure of adaptive behavior.⁸

Critics attacked the AAMR definition as erecting a boundary between mentally retarded and intellectually normal people where no such boundary exists in human biology. They argued that, rather than comprising a uniform and homogeneous group that is distinct from cognitively normal persons, mentally retarded persons merely occupy one end of a continuous spectrum of intellectual and functional capacities. Within this continuum, there is no distinct boundary but only a gradual blending between the intellectually normal and the mentally retarded. The AAMR definition, they concluded, created an artificial label that encouraged stigmatization and permitted discrimination.⁹

In 2002, the AAMR again revised its definition of mental retardation to the following: “Mental retardation is a disability characterized by significant limitations both in intellectual functioning and in adaptive behavior as expressed in conceptual, social, and practical adaptive skills.”¹⁰ In January 2007, the AAMR jettisoned over 130 years of tradition by replacing the term “mental retardation” with “intellectual disability” and changed its own name to the American Association on Intellectual and Developmental Disabilities (AAIDD).¹¹ These changes were consistent with the World Health Organization’s 2001 revision of the Interna-tional Classification of Functioning, Disability, and Health that “puts the notions of ‘health’ and ‘disability’ in a new light. It acknowledges that every human being can experience a decrement in health and thereby experience some degree of disability. Disability is not something that only happens to a minority of humanity. The ICF thus ‘mainstreams’ the experience of disability and recognises it as a universal human experience.”¹² Despite the recent AAMR (AAIDD) recommendation, I use the more familiar term “mental retardation” in this chapter.

The incidence and prevalence of mental retardation have been difficult to quantify because it has not been differentiated from other developmental disabilities, particularly severe states of dyslexia, and because of the confounding effect of illiteracy on the testing paradigm. In an examination of prevalence data in the United States prior to 1962, the President’s Panel on Mental Retardation reported that 3% of the American population was mentally retarded. Of this group of approximately 5.4 million people, the panel classified 87% as mildly retarded, 10% as moderately retarded, and 1% as severely retarded.¹³

To discourage citing this 3% figure as a precise measure of the prevalence of mental retardation, the panel stated that the 3% figure represents those people who are mentally retarded “at some time in their lives.” Several unverified assumptions have made the 3% figure questionable as a fixed estimate of prevalence: (1) all such patients had an IQ less than 70; (2) mental retardation can be diagnosed accurately in infancy; (3) the diagnosis of mental retardation does not change throughout life; and (4) the mortality rate of retarded patients is identical to that of the general population.¹⁴ In 1997, Nel Roeleveld and colleagues conducted a critical review of the
world’s literature on the prevalence of mental retardation. Despite variation among countries, they found that the mean of school-age children who are retarded is 3%, with a relatively fixed rate of severe retardation of 3.8/1,000 children.¹⁵

Mental retardation is not a unitary disease but a syndrome in which a range of severity of brain damage or malformation can be produced by a multitude of prenatal, perinatal, and postnatal disorders. The differential diagnosis of a patient with mental retardation includes hundreds of disorders that are most easily understood when classified into groups by pathogenesis. Thus, mental retardation can be produced by prenatal and postnatal infections; birth trauma; metabolic, toxic, nutritional, and endocrine diseases; neurocutaneous and neurodegenerative disorders; congenital malformations; chromosomal aberrations, microdeletions, and mutations; fetal prematurity; and acquired childhood disorders.

A recent epidemiological study of 715 mentally retarded 10-year-old children in Atlanta found prenatal causes in 12%, perinatal causes in 6%, postnatal causes in 4% and no reported cause in 78% of cases.¹⁶ The relative incidence of each of the major diagnostic groups was studied by Allen Crocker in the 1970s in a series of 2,000 patients he examined in the Developmental Evaluation Clinic at the Boston Children’s Hospital Medical Center.¹⁷ Crocker found the following breakdown by diagnostic group:

Screening to determine the specific causes of global developmental delay is advocated by the American Academy of Pediatrics,¹⁸ the American Academy of Neurology (AAN), and the Child Neurology Society (CNS). In a recent evidence-based review, the AAN and the CNS offered several guidelines.¹⁹ Because inborn errors of metabolism are currently seen in only about 1% of cases, screening for them is not recommended. Cytogenetic testing is positive in 3.7% and should be carried out even in the absence of dysmorphic features. Fragile X syndrome accounts for 2.6% and may be tested. Rett syndrome and the MECP2 gene may be investigated. Additional genetic testing may be conducted to look for subtelomeric chromosome rearrangements, accounting for 6.6% of cases. If children are at risk for lead poisoning, lead levels should be measured. Hypothyroidism should be excluded if not already screened neonatally. An EEG may be helpful if seizures are present. Neuroimaging by brain CT scan or MRI should be done because it increases diagnostic specificity. Tests of vision and hearing should be performed because they are useful diagnostically. The specific diagnosis should be communicated to the parents or caregivers according to established standards of “breaking bad news” once it is established.²⁰

New molecular genetic techniques are revolutionizing diagnostic testing for genetic causes of mental retardation.²¹ The genetic etiology of mental retardation currently remains unknown in over half of cases.²² Innovative techniques such as DNA microarray analysis can identify DNA submicroscopic copy number variations, such as deletions, insertions, duplications, and complex multisite variations, and can pinpoint genetic abnormalities in at least 10% of previously undiagnosed cases, particularly in retarded children with dysmorphic syndromes.²³

Complete management of the mentally retarded patient requires attention to five general areas: (1) specific medical treatment for the underlying disease; (2) symptomatic treatment for complications resulting from the underlying disease; (3) psychological treatment; (4) educational and vocational counseling; and (5) prevention. Adequate treatment of the retarded patient begins with a thorough
medical and neurological examination, including tests of vision and hearing, followed by psychological, social, educational, rehabilitative, and vocational evaluations.²⁴

Specific medical treatment to counteract the pathophysiological effects of hereditary metabolic disorders or to replace congenitally absent proteins or enzymes has been modestly successful for only a few of the disorders that produce mental retardation. For example, the combination of erucic and oleic acids (“Lorenzo’s oil”) has been used with limited success to treat X-linked adrenoleukodystrophy in children,²⁵ but the benefits of treatment have been overstated by the popular media.²⁶ Similarly, macrophage-targeted alglucerase and glucocerebrosidase have been used with limited success to treat Gaucher disease²⁷ and agalsidase-beta treatment can slow the progression of Fabry disease.²⁸ Despite the equivocal benefits currently resulting from this form of therapy, it is likely that specific therapy targeted to replace absent proteins or enzymes in several of the disorders will be more successful with future advances in technology.

Medical complications of mental retardation include seizures, spasticity, choreoathetosis, and behavioral and attentional disturbances. Seizure disorders can be treated with anticonvulsant medications to optimize control and minimize sedation and psychomotor retardation. Spasticity can be treated with medications, orthotics, physical therapy, and orthopedic surgery to minimize discomfort and maximize motor function. Choreoathetosis and other movement disorders can be suppressed with medications.

Behavioral, attentional, and other psychological disturbances can be treated with medications, psychotherapy, and behavioral modification therapies. The goal of these therapies is to maximize the patient’s cognitive function, and not simply to control disruptive behavior to ease the burdens of nursing care. Educational counseling during childhood and vocational training during adolescence are important components of rehabilitation because they maximize the useful function of the retarded patient.

Mental retardation can be prevented through several strategies. The nutrition and general health of pregnant women should be maximized with adequate prenatal medical care. Tobacco, alcohol, street drugs, and all unnecessary medications should be avoided during all stages of pregnancy. Prenatal genetic screening and counseling, newborn diagnostic screening, amniocentesis, and early elective abortion should be more widely available to prevent genetic diseases. Child neglect and abuse should be identified and stopped by timely intervention.

The essential ethical problem in the medical care of the mentally retarded patient is how to obtain valid consent for diagnosis or treatment. Many of the other clinical-ethical problems arising in the care of these patients stem directly from the consent question. Thus, the ethical issues that surround involuntary sterilization, sedation for frightening medical procedures, prescribing psychotropic medications, behavioral conditioning techniques to modify disruptive behavior, limitation or termination of life-sustaining medical treatment, and research on the retarded patient are all variations of the consent issue.

Respect for human dignity requires that mentally retarded people have the same moral right as cognitively intact people to consent to or refuse tests or therapies.²⁹ As persons, they also have a legal right that is not extinguished by their cognitive incapacity and that can be exercised by a surrogate decision maker on behalf of the patient.³⁰ The specific rights of consent of the mentally retarded patient have been codified into law in many countries, as discussed in the section on legal issues later in this chapter. Guardians and other lawful surrogates have authority to consent for or refuse many therapies on behalf of the patient but state statutes and regulations may restrict the authority of guardians and require judicial approval for certain treatments including sterilization, abortion, electroconvulsive therapy and psychosurgery.³¹

The issue of valid consent in the mentally retarded patient has certain features in common
with consent issues in other incompetent patients such as elderly demented patients, but it also contains unique aspects. The severely retarded patient not only is incompetent at any given time to provide consent, he never has been and never will be competent to provide consent at any future time. The patient can be thus categorized as “never competent.” This circumstance differs in important ways from that of a demented adult who once was competent. Also, there are subtle but important differences between obtaining consent in the mentally retarded patient and obtaining consent in a young child. Although the young child is incompetent, he has the potential to become competent in the future.

A competent adult rendered incompetent by delirium or dementia (chapter 15) has a life history of health-care values that he had expressed verbally or in writing, or that can be gleaned by analyzing his past behavior. These values can be inspected and followed to determine how the patient likely would have responded to questions of consent for a course of medical treatment. Following the standard of substituted judgment, a surrogate decision maker applies the patient’s previously expressed values to his current clinical situation to attempt to reproduce the decision that the patient would have made for himself when he was competent (see chapter 4). A process of substituted judgment realistically cannot be used in making decisions for a mentally retarded patient because of the impossibility of his having any history of previously expressed values.³²

There is a similarity between consent questions in the mentally retarded patient of any age and consent questions in the young child. Because both the very young child and the retarded patient are incompetent and never have been competent, the substituted judgment standard cannot be used for either. Procedurally, consent questions should be handled similarly in both a normal child and a retarded patient of any age with the mental capacity equivalent to that of a normal child. Thus, consent questions are treated substantially in the same manner for a normal 18-month-old and for a retarded adult patient with the mental capacity of a normal 18-month-old.

In both circumstances, the best interest judgment is the preferred decision-making standard. Surrogate decision makers should strive to identify, as objectively as possible, the decision that is in the best interest of the patient. Best interest decisions are less powerful ethically than substituted judgment decisions because surrogate decision makers respect the patient’s autonomy in the latter by attempting to follow the course of action that the patient most likely would have chosen. The President’s Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research recommended that the best interest standard should be employed when surrogates make medical decisions for never-competent patients.³³

A best interest judgment requires balancing the expected benefits of a proposed test or therapy against its expected burdens. This balance is determined by the surrogate decision maker, who employs his or her own assessments and predictions of the burdens and benefits to the patient. In this way, the best interest standard differs from the substituted judgment standard, in which the patient’s own balance of burdens and benefits is approximated. If the expected benefits are greater than the burdens, the surrogate consents to the proposed therapy or test. If the burdens exceed the benefits, the best interest standard would rule that a rational surrogate should refuse to provide consent.³⁴

The spectrum of cognitive capacity in mentally retarded patients varies as a function of the severity of brain damage in the same way that the spectrum of cognitive capacity in normal children varies as a function of age. No consent other than that of the surrogate is necessary in a profoundly retarded patient or in a child under the age of five years. With lesser degrees of retardation and in older children, the clinician should attempt to obtain the patient’s assent by explaining the matter to him to the extent that he can comprehend. To make a patient’s assent into valid consent, the surrogate decision maker also must provide consent. The concept of assent was developed for children but is applicable also to patients with less severe forms of dementia and mental retardation.³⁵

Applying the best interest standard to a mentally retarded patient and to a child of the same mental age discloses the differences between these two situations. Normal incompetent children are expected to develop into competent adults, whereas incompetent retarded patients will never become competent adults. Therefore, the benefits-to-burdens ratio of a given treatment may be interpreted differently in these two groups.

Consider, for example, a cognitively intact 18-month-old girl with newly diagnosed acute lymphoblastic leukemia (ALL) and a severely retarded 50-year-old woman, with the mental age of an 18-month-old, who also has newly diagnosed ALL. Neither patient can understand the reason that she is being hospitalized and frequently injected with noxious chemotherapeutic drugs. All both know is that they feel violently ill, scream with pain, vomit uncontrollably, and are terribly frightened of doctors, nurses, and needles.

The parents of the child may decide that it is in her best interest to undergo the substantial amount of pain and suffering imposed by chemotherapy because her chances of recovery from this otherwise fatal disease are good, making her life expectancy thereafter relatively normal. Therefore, they consent to the treatment by a best interest standard, accepting the child’s suffering as an unpleasant and regrettable but necessary and fully justified price to pay for the intended goal of therapy.

Conversely, the guardian of the retarded woman may decide that it is not in the patient’s best interest to undergo substantial pain and suffering accompanying medical treatment because those burdens are not counterbalanced by the expectancy of a normal life thereafter. The guardian may decide that the suffering caused by the treatment cannot be justified by its expected benefits. Although the decision-making procedure may be the same for the two cases, a different substantive decision may have been reached because the prognostic differences significantly influence the surrogate’s perception of the balance of the benefits and burdens of treatment to the patient. The close collaboration and shared decision making between the parent or guardian and the physician are essential to reach the decision that is in the patient’s best interest.

In no area are the ethical conflicts of consent, autonomy, and paternalism brought into clearer focus than in the consideration of involuntary sterilization of a mentally retarded patient. Advocates of this practice point out that mentally retarded patients cannot understand the fundamental facts of sexuality and procreation sufficiently to be responsible for their own sexual behavior. Further, they lack the capacity to raise children that they have conceived irresponsibly or unknowingly. Finally, retarded patients may pass along hereditary diseases to their offspring and thereby perpetuate their medical and social problems into the next generation. In times past, the obvious solution was to sterilize mentally retarded patients involuntarily for their own good and for the good of society.³⁶

The social and legal history of involuntary sterilization is colorful but sobering.³⁷ Eugenic theories were commonly accepted in the United States and England in the late nineteenth and early twentieth centuries. In 1907, Indiana became the first of over 30 states to enact a law authorizing involuntary sterilization of the retarded based on the preceding argument.³⁸ Implicit in these laws was overt discrimination against and stigmatization of the retarded patient. For example, in the famous 1927 U.S. Supreme Court case of Buck v Bell, Justice Oliver Wendell Holmes, Jr. had this to say about the proposed involuntary sterilization of Carrie Buck:

Although the majority of states had enacted sterilization statutes by the 1930s, the U.S. Supreme Court struck down the Oklahoma eugenic sterilization law as unconstitutional in 1942, asserting that procreation was a fundamental right of American citizens. The Court also expressed concern that forced sterilization could “cause races or types which are inimical to the dominant group to wither and disappear.”⁴⁰ Spurred by the horror of the involuntary sterilization practices in Nazi Germany ⁴¹ and the growing civil rights movement in the United States of the 1950s and 1960s, most state legislatures repealed their involuntary sterilization statutes by the 1970s.

In 1979, federal regulations were written barring the use of federal funds to pay for sterilization of mentally retarded patients.⁴² As of 1989, twenty states had retained statutes permitting surrogate decision makers to consent to sterilization of a mentally retarded patient, and eight others defined a judicial process for doing so.⁴³ The laws of the United Kingdom, Australia, and Canada require approval of a high court to permit sterilization of a mentally retarded patient.⁴⁴ South Africa has enacted a national statute to provide legal sanction for involuntary sterilization.⁴⁵

Medical societies and scholars have attempted to formulate stringent criteria for the ethical practice of involuntary sterilization. The American College of Obstetricians and Gynecologists (ACOG) published a position paper in 1988 summarizing the relevant medical, ethical, and legal issues of involuntary sterilization. The ACOG stated that the surrogate decision makers should be the parents, immediate family members, or legal guardians of the mentally retarded person. The surrogate should utilize a best interest standard, but the surrogate’s decision should be inspected by the physician to assure that there is no conflict of interest. All alternatives to sterilization, such as contraception training, should be considered first. To guarantee that the decision to sterilize is in the patient’s best interest, certain facts should be ascertained: (1) the patient’s mental incapacity is permanent; (2) the patient is fertile and likely to engage in sexual intercourse; (3) the pregnancy poses a serious health risk or disproportionate burden to the patient; and (4) the pregnancy would pose a significant risk of a serious congenital disorder in the infant. Relevant laws in the jurisdiction should be followed.⁴⁶

In 1990, the American Academy of Pediatrics reprinted the ACOG report with an accompanying position paper of its own, emphasizing several points. Girls before menarche should not be sterilized. The primary or contributing indications for sterilization based on “presumed or anticipated hardship to others” should be viewed with great skepticism, in light of acceptable alternatives to sterilization such as pharmacological contraception. Deter-mination of “hardship” should be rigorous, and sterilization should not be performed simply as a convenience. Physicians should attempt to obtain informed consent from the patient, and, to the fullest extent possible, they should include the patient in the decision-making process. At all times, physicians should choose the least invasive, least permanent, and safest technique.⁴⁷ To these reasonable criteria should be added that newer, less invasive, long-duration hormonal treatments may satisfactorily achieve contraception in some patients without requiring surgical sterilization.⁴⁸

In the less retarded patient, consent for sterilization with a careful explanation of the indications, risks, benefits, and alternatives of the procedure always should be obtained. Failure to obtain the patient’s consent should not, itself, be evidence that the patient is incompetent or has made an irrational decision. As Daniel Wikler pointed out, “the fact that some retarded persons pose a threat to their own welfare is not in itself sufficient reason to deny them the liberty to do so.”⁴⁹ For more severely retarded patients, one philosopher asserted recently “If some of these persons are fertile and sexually active, it may be very well the morally right thing to do to sterilize [them], in their own best interest, but without their consent—if necessary even through coercive means.”⁵⁰ Between these two extreme positions, the ethical analyses of most scholars have relied on a utilitarian balance of the benefits and risks of sterilization to the patient once necessity has been established.⁵¹

Joseph Rauh and colleagues, after a review of their own substantial experience with a carefully planned sterilization program, have proposed a model statute they call the “voluntary sterilization act.” They believe that the act should be adopted by all states to assure the proper balance of ethical considerations and legal rights for all parties in this debate. Their proposed statute contains the following provisions:

In a similar attempt to justify the ethical and legal acceptability of involuntary sterilization to maximally protect the retarded patient, Judith Areen proposed the following list of legal procedural criteria: