mental retardation

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Definition

Mental retardation is a developmental disability that first appears in children under the age of 18. It is defined as an intellectual functioning level (as measured by standard tests for intelligence quotient) that is well below average and significant limitations in daily living skills (adaptive functioning).

Description

Mental retardation occurs in 2.5-3% of the general population. About 6-7.5 million mentally retarded individuals live in the United States alone. Mental retardation begins in childhood or adolescence before the age of 18. In most cases, it persists throughout adulthood. A diagnosis of mental retardation is made if an individual has an intellectual functioning level well below average and significant limitations in two or more adaptive skill areas. Intellectual functioning level is defined by standardized tests that measure the ability to reason in terms of mental age (intelligence quotient or IQ). Mental retardation is defined as IQ score below 70-75. Adaptive skills are the skills needed for daily life. Such skills include the ability to produce and understand language (communication); home-living skills; use of community resources; health, safety, leisure, self-care, and social skills; self-direction; functional academic skills (reading, writing, and arithmetic); and work skills.

In general, mentally retarded children reach developmental milestones such as walking and talking much later than the general population. Symptoms of mental retardation may appear at birth or later in childhood. Time of onset depends on the suspected cause of the disability. Some cases of mild mental retardation are not diagnosed before the child enters preschool. These children typically have difficulties with social, communication, and functional academic skills. Children who have a neurological disorder or illness such as encephalitis or meningitis may suddenly show signs of cognitive impairment and adaptive difficulties.

Mental retardation varies in severity. The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) is the diagnostic standard for mental healthcare professionals in the United States. The DSMIV classifies four different degrees of mental retardation: mild, moderate, severe, and profound. These categories are based on the functioning level of the individual.

Approximately 85% of the mentally retarded population is in the mildly retarded category. Their IQ score ranges from 50-75, and they can often acquire academic skills up to the 6th grade level. They can become fairly self-sufficient and in some cases live independently, with community and social support.

About 10% of the mentally retarded population is considered moderately retarded. Moderately retarded individuals have IQ scores ranging from 35-55. They can carry out work and self-care tasks with moderate supervision. They typically acquire communication skills in childhood and are able to live and function successfully within the community in a supervised environment such as a group home.

About 3-4% of the mentally retarded population is severely retarded. Severely retarded individuals have IQ scores of 20-40. They may master very basic self-care skills and some communication skills. Many severely retarded individuals are able to live in a group home.

Only 1-2% of the mentally retarded population is classified as profoundly retarded. Profoundly retarded individuals have IQ scores under 20-25. They may be able to develop basic self-care and communication skills with appropriate support and training. Their retardation is often caused by an accompanying neurological disorder. The profoundly retarded need a high level of structure and supervision.

The American Association on Mental Retardation (AAMR) has developed another widely accepted diagnostic classification system for mental retardation. The AAMR classification system focuses on the capabilities of the retarded individual rather than on the limitations. The categories describe the level of support required. They are: intermittent support, limited support, extensive support, and pervasive support. To some extent, the AAMR classification mirrors the DSM-IV classification. Intermittent support, for example, is support needed only occasionally, perhaps during times of stress or crisis. It is the type of support typically required for most mildly retarded individuals. At the other end of the spectrum, pervasive support, or life-long, daily support for most adaptive areas, would be required for profoundly retarded individuals.

— Paula Anne Ford-Martin

Subnormal intellectual development as a result of congenital causes, brain injury, or disease and characterized by any of various cognitive deficiencies, including impaired learning, social, and vocational ability. Also called mental deficiency.

Definition

Mental retardation (MR) is a developmental disability that first appears in children under the age of 18. It is defined as a level of intellectual functioning (as measured by standard intelligence tests) that is well below average and results in significant limitations in the person's daily living skills (adaptive functioning).

Description

Mental retardation begins in childhood or adolescence before the age of 18. In most cases, it persists throughout adult life. A diagnosis of mental retardation is made if an individual has an intellectual functioning level well below average, as well as significant limitations in two or more adaptive skill areas. Intellectual functioning level is defined by standardized tests that measure the ability to reason in terms of mental age (intelligence quotient or IQ). Mental retardation is defined as an IQ score below 70–75; a normal score is 100. Adaptive skills refer to skills needed for daily life. Such skills include the ability to produce and understand language (communication); home-living skills; use of community resources; health, safety, leisure, self-care, and social skills; self-direction; functional academic skills (reading, writing, and arithmetic); and job-related skills.

In general, mentally retarded children reach such developmental milestones as walking and talking much later than children in the general population. Symptoms of mental retardation may appear at birth or later in childhood. The child's age at onset depends on the suspected cause of the disability. Some cases of mild mental retardation are not diagnosed before the child enters preschool or kindergarten. These children typically have difficulties with social, communication, and functional academic skills. Children who have a neurological disorder or illness such as encephalitis or meningitis may suddenly show signs of cognitive impairment and adaptive difficulties.

Mental retardation varies in severity. The Diagnostic and Statistical Manual of Mental Disorders, fourth edition, text revision (DSM-IV-TR), which is the diagnostic standard for mental healthcare professionals in the United States, classifies four degrees of mental retardation: mild, moderate, severe, and profound. These categories are based on the person's level of functioning.

Mild mental retardation

Approximately 85% of the mentally retarded population is in the mildly retarded category. Their IQ score ranges from 50–70, and they can often acquire academic skills up to about the sixth-grade level. They can become fairly self-sufficient and, in some cases, live independently, with community and social support.

Moderate mental retardation

About 10% of the mentally retarded population is considered moderately retarded. These people have IQ scores ranging from 35–55. They can carry out work and self-care tasks with moderate supervision. They typically acquire communication skills in childhood and are able to live and function successfully within the community in such supervised environments as group homes.

Severe mental retardation

About 3–4% of the mentally retarded population is severely retarded. They have IQ scores of 20–40. They may master very basic self-care skills and some communication skills. Many severely retarded individuals are able to live in a group home.

Profound mental retardation

Only 1–2% of the mentally retarded population is classified as profoundly retarded. These individuals have IQ scores under 20–25. They may be able to develop basic self-care and communication skills with appropriate support and training. Their retardation is often caused by an accompanying neurological disorder. Profoundly retarded people need a high level of structure and supervision.

AAMR classifications

The American Association on Mental Retardation (AAMR) has developed another widely accepted diagnostic classification system for mental retardation. The AAMR classification system focuses on the capabilities of retarded individuals rather than on their limitations. The categories describe the level of support required, including intermittent support, limited support, extensive support, and pervasive support. To some extent, the AAMR classification mirrors the DSM-IV-TR classification. Intermittent support, for example, is support that is needed only occasionally, perhaps during times of stress or crisis for the retarded person. It is the type of support typically required for most mildly retarded people. At the other end of the spectrum, pervasive support, which is life-long, daily support for most adaptive areas, would be required for profoundly retarded persons. The AAMR classification system refers to the "below-average intellectual function" as an IQ of 70–75 or below.

Demographics

The prevalence of mental retardation in North America is a subject of heated debate. It is thought to be 1–3% of the population, depending on the methods of assessment and criteria of assessment that are used. Many people believe that the actual prevalence is probably closer to 1%, and that the 3% figure is based on misleading mortality rates, cases that are diagnosed in early infancy, and the instability of the diagnosis across the age span. If the 1% figure is accepted, however, that means that 2.5 million mentally retarded people reside in the United States. Males are more likely than females to be mentally retarded at a 1.5:1 ratio.

Causes and symptoms

Causes

A variety of problems can lead to mental retardation. The three most common causes of mental retardation, accounting for about 30% of cases, are Down syndrome, fragile X, and fetal alcohol syndrome. In about 40% of cases, the cause of mental retardation cannot be found. The causes of mental retardation can be divided into broad classifications, including genetic factors, prenatal illnesses and exposures, childhood illnesses and injuries, and environmental factors.

GENETIC FACTORS About 30% of cases of mental retardation are caused by hereditary factors. Mental retardation may be caused by an inherited genetic abnormality such as fragile X syndrome. Fragile X, a defect in the chromosome that determines sex, is the most common inherited cause of mental retardation. Single-gene defects such as phenylketonuria (PKU) and other inborn errors of metabolism may also cause mental retardation if they are not discovered and treated early. An accident or mutation in genetic development may also cause retardation. Examples of such accidents are development of an extra chromosome 18 (trisomy 18) and Down syndrome. Down syndrome, also called mongolism or trisomy 21, is caused by an abnormality in the development of chromosome 21. It is the most common genetic cause of mental retardation.

PRENATAL ILLNESSES AND EXPOSURES Fetal alcohol syndrome (FAS) affects one in 3,000 children in Western countries. Fetal alcohol syndrome results from the mother's heavy drinking during the first 12 weeks (trimester) of pregnancy. Some studies have shown that even moderate alcohol use during pregnancy may cause learning disabilities in children. Drug abuse and cigarette smoking during pregnancy have also been linked to mental retardation. It is generally accepted that pregnant women should avoid all alcohol, tobacco, and recreational drugs.

Maternal infections and such illnesses as glandular disorders, rubella, toxoplasmosis, and cytomegalovirus (CMV) infection may cause mental retardation. When the mother has high blood pressure (hypertension) or blood poisoning (toxemia), the flow of oxygen to the fetus may be reduced, causing brain damage and mental retardation.

Birth defects that cause physical deformities of the head, brain, and central nervous system frequently cause mental retardation. Neural tube defect, for example, is a birth defect in which the neural tube that forms the spinal cord does not close completely. This defect may cause children to develop an accumulation of cerebrospinal fluid inside the skull (hydrocephalus). Hydrocephalus can cause learning impairment by putting pressure on the brain.

CHILDHOOD ILLNESSES AND INJURIES Hyperthyroidism, whooping cough, chicken pox, measles, and Hib disease (a bacterial infection) may cause mental retardation if they are not treated adequately. An infection of the membrane covering the brain (meningitis) or an inflammation of the brain itself (encephalitis) can cause swelling that in turn may cause brain damage and mental retardation. Traumatic brain injury caused by a blow to the head or by violent shaking of the upper body may also cause brain damage and mental retardation in children.

ENVIRONMENTAL FACTORS Ignored or neglected infants who are not provided with the mental and physical stimulation required for normal development may suffer irreversible learning impairment. Children who live in poverty and suffer from malnutrition, unhealthy living conditions, abuse, and improper or inadequate medical care are at a higher risk. Exposure to lead or mercury can also cause mental retardation. Many children have developed lead poisoning from eating the flaking lead-based paint often found in older buildings.

Symptoms

Low IQ scores and limitations in adaptive skills are the hallmarks of mental retardation. Aggression, self-in-jury, and mood disorders are sometimes associated with the disability. The severity of the symptoms and the age at which they first appear depend on the cause. Children who are mentally retarded reach developmental milestones significantly later than expected, if at all. If retardation is caused by chromosomal or other genetic disorders, it is often apparent from infancy. If retardation is caused by childhood illnesses or injuries, learning and adaptive skills that were once easy may suddenly become difficult or impossible to master.

Diagnosis

If mental retardation is suspected, a comprehensive physical examination and medical history should be done immediately to discover any organic cause of symptoms. Such conditions as hyperthyroidism and PKU are treatable. The progression of retardation can be stopped and, in some cases, partially reversed if these conditions are discovered early. If a neurological cause such as brain injury is suspected, the child may be referred to a neurologist or neuropsychologist for testing.

A complete medical, family, social, and educational history is compiled from existing medical and school records (if applicable) and from interviews with parents. Children are given intelligence tests to measure their learning abilities and intellectual functioning. Such tests include the Stanford-Binet Intelligence Scale, the Wechsler Intelligence Scales, the Wechsler Preschool and Primary Scale of Intelligence, and the Kaufman Assessment Battery for Children. For infants, the Bayley Scales of Infant Development may be used to assess motor, language, and problem-solving skills. Interviews with parents or other caregivers are used to assess the child's daily living, muscle control, communication, and social skills. The Woodcock-Johnson Scales of Independent Behavior and the Vineland Adaptive Behavior Scale are frequently used to evaluate these skills.

Treatment team

The treatment team will depend on the underlying cause of mental retardation. A neurologist, neuropsychologist, child psychiatrist, and/or development pediatrician may be helpful for nearly all cases of mental retardation, both to assess underlying cause and to plan for appropriate and helpful interventions. Other members of the treatment team will depend on the underlying cause of mental retardation, accompanying medical problems, and the severity of the deficits.

Treatment

Federal legislation entitles mentally retarded children to free testing and appropriate, individualized education and skills training within the school system from ages three to 21. For children under the age of three, many states have established early intervention programs that assess children, make recommendations, and begin treatment programs. Many day schools are available to help train retarded children in such basic skills as bathing and feeding themselves. Extracurricular activities and social programs are also important in helping retarded children and adolescents gain self-esteem.

Training in independent living and job skills is often begun in early adulthood. The level of training depends on the degree of retardation. Mildly retarded people can often acquire the skills needed to live independently and hold an outside job. Moderate to profoundly retarded persons usually require supervised community living in a group home or other residential setting.

Family therapy can help relatives of the mentally retarded develop coping skills. It can also help parents deal with feelings of guilt or anger. A supportive, warm home environment is essential to help the mentally retarded reach their full potential.

Prognosis

People with mild to moderate mental retardation are frequently able to achieve some self-sufficiency and to lead happy and fulfilling lives. To reach these goals, they need appropriate and consistent educational, community, social, family, and vocational supports. The outlook is less promising for those with severe to profound retardation. Studies have shown that these persons have a shortened life expectancy. The diseases that are usually associated with severe retardation may cause the shorter lifespan. People with Down syndrome will develop the brain changes that characterize Alzheimer's disease in later life and may develop the clinical symptoms of this disease as well.

Special concerns

Prevention

Immunization against diseases such as measles and Hib prevents many of the illnesses that can cause mental retardation. In addition, all children should undergo routine developmental screening as part of their pediatric care. Screening is particularly critical for those children who may be neglected or undernourished or may live in diseaseproducing conditions. Newborn screening and immediate treatment for PKU and hyperthyroidism can usually catch these disorders early enough to prevent retardation.

Good prenatal care can also help prevent retardation. Pregnant women should be educated about the risks of alcohol consumption and the need to maintain good nutrition during pregnancy. Such tests as amniocentesis and ultrasonography can determine whether a fetus is developing normally in the womb.

Resources

BOOKS

American Psychiatric Association. "Mental Retardation." In Diagnostic and Statistical Manual of Mental Disorders, 4th ed., text revision. Washington, DC: American Psychiatric Press, Inc., 2000.

Jaffe, Jerome H., M.D. "Mental Retardation." In Comprehensive Textbook of Psychiatry, edited by Benjamin J. Sadock, MD, and Virginia A. Sadock, MD. 7th edition. Philadelphia, PA: Lippincott Williams and Wilkins, 2000.

Julian, John N. "Mental Retardation." In Psychiatry Update and Board Preparation, edited by Thomas A. Stern, MD, and John B. Herman, MD. New York: McGraw Hill, 2000.

PERIODICALS

Bozikas, Vasilis, MD, et al. "Gabapentin for Behavioral Dyscontrol with Mental Retardation." American Journal Psychiatry June 2001: 965–966.

Margolese, Howard C., MD, et al. "Olanzapine-Induced Neuroleptic Malignant Syndrome with Mental Retardation." American Journal Psychiatry July 1999: 1115A–1116.

ORGANIZATIONS

American Association on Mental Retardation (AAMR). 444 North Capitol Street, NW, Washington, D.C. 20001. (800) 424-3688. http://www.aamr.org.

The Arc of the United States (formerly Association of Retarded Citizens of the United States). 1010 Wayne Avenue, Silver Spring, M.D. 20910. (301) 565-3842. http://thearc.org.

OTHER

National Information Center for Children and Youth and Disabilities. P.O. Box 1492, Washington, D.C. 20013. (800) 695-0285. http://www.nichcy.org.

Paula Anne Ford-Martin

Rosalyn Carson-DeWitt, MD

A developmental disability characterized by significantly subaverage general intellectual functioning, with concurrent deficits in adaptive behavior. The causes are many and include both genetic and environmental factors as well as interactions between the two. In most cases the diagnosis is not formally made until children have entered into school settings. In the preschool years, the diagnosis is more likely to be established by evidence of delayed maturation in the areas of sensory-motor, adaptive, cognitive, social, and verbal behaviors. By definition, evidence of mental retardation must exist prior to adulthood, where vocational limitation may be evident, but the need for supervision or support may persist beyond the usual age of social emancipation.

From the aspect of etiology, mental retardation can be classified by prenatal, perinatal, or postnatal onset. Prenatal causes include genetic disorders, syndromal disorders, and developmental disorders of brain formation. Upward of 700 genetic causes have been suggested as associated with the development of mental retardation. Many environmental influences on the developing fetus, for example, infection, and other unknown errors of development may account for mental retardation.

Perinatal causes include complications at birth, extreme prematurity, infections, and other neonatal disorders. Postnatal causes include trauma, infections, demyelinating and degenerative disorders, consequences of seizure disorders, toxic-metabolic disorders, malnutrition, and environmental deprivation. Often no specific cause can be identified for the mental retardation of a particular individual.

Individuals with mental retardation are typically subclassified in terms of the manifest severity of cognitive disability as reflected by the ratio of mental age to chronological age, or intelligence quotient (IQ). Subaverage intellectual functioning is defined as an IQ score of at least two standard deviations below the mean, or approximately 70 to 75 or below. Mild, moderate, severe, and profound degrees of mental retardation refer to two, three, four, or five standard deviations below the normal IQ for the general population.

Limitations in adaptive behavior must also be demonstrable in order to satisfy diagnostic criteria for mental retardation. This criterion is important because certain artistic or other gifts may not be revealed by formal IQ testing, and different levels of learning difficulty may be accentuated by the demands of specific environments. Outside such environments, an individual may navigate a normal course in life.

A specific genetic or other cause of mental retardation may also predispose to other medical or neurologic conditions. In these circumstances, the comorbid medical conditions may increase the likelihood of emotional or behavioral problems, or contribute to the challenges with which a given child must contend. Thus, the identification of cause can be important in planning for the medical, educational, and treatment needs of a particular individual.

Considerable progress has been made in both prevention and treatment. Diet is a method of treatment following early detection of phenylketonuria; warnings regarding alcohol consumption during pregnancy, lead exposure in infancy, and disease immunization and therapy are measures for prevention of retardation. Advances in prenatal, obstetrical, and neonatal care and genetic counseling have had the effect of reducing the incidence or the severity of various conditions. Energetic training and the application of psychosocial techniques have resulted in improved social performance and adaptive behavior in many persons with mental retardation.

A disorder of general intellectual function impairing the ability to learn and adapt socially.

Definition

Mental retardation is a developmental disability that first appears in children under the age of 18. It is defined as an intellectual functioning level (as measured by standard tests for intelligence quotient) that is well below average and significant limitations in daily living skills (adaptive functioning).

Description

According to statistics made available by the Centers for Disease Control and Prevention in the 1990s, mental retardation occurs in 2.5 to 3 percent of the general population. About 6 to 7.5 million mentally retarded individuals live in the United States alone. Mental retardation begins in childhood or adolescence before the age of 18. In most cases, it persists throughout adulthood. A diagnosis of mental retardation is made if an individual has an intellectual functioning level well below average and significant limitations in two or more adaptive skill areas. Intellectual functioning level is defined by standardized tests that measure the ability to reason in terms of mental age (intelligence quotient or IQ). Mental retardation is defined as IQ score below 70 to 75. Adaptive skills are the skills needed for daily life. Such skills include the ability to produce and understand language (communication); home-living skills; use of community resources; health, safety, leisure, self-care, and social skills; self-direction; functional academic skills (reading, writing, and arithmetic); and work skills.

In general, mentally retarded children reach developmental milestones such as walking and talking much later than the general population. Symptoms of mental retardation may appear at birth or later in childhood. Time of onset depends on the suspected cause of the disability. Some cases of mild mental retardation are not diagnosed before the child enters preschool. These children typically have difficulties with social, communication, and functional academic skills. Children who have a neurological disorder or illness such as encephalitis or meningitis may suddenly show signs of cognitive impairment and adaptive difficulties.

Mental retardation varies in severity. There are four different degrees of mental retardation: mild, moderate, severe, and profound. These categories are based on the functioning level of the individual.

Mild Mental Retardation

Approximately 85 percent of the mentally retarded population is in the mildly retarded category. Their IQ score ranges from 50 to 75, and they can often acquire academic skills up to the sixth grade level. They can become fairly self-sufficient and in some cases live independently, with community and social support.

Moderate Mental Retardation

About 10 percent of the mentally retarded population is considered moderately retarded. Moderately retarded individuals have IQ scores ranging from 35 to 55. They can carry out work and self-care tasks with moderate supervision. They typically acquire communication skills in childhood and are able to live and function successfully within the community in a supervised environment such as a group home.

Severe Mental Retardation

About 3 to 4 percent of the mentally retarded population is severely retarded. Severely retarded individuals have IQ scores of 20 to 40. They may master very basic self-care skills and some communication skills. Many severely retarded individuals are able to live in a group home.

Profound Mental Retardation

Only 1 to 2 percent of the mentally retarded population is classified as profoundly retarded. Profoundly retarded individuals have IQ scores under 20 to 25. They may be able to develop basic self-care and communication skills with appropriate support and training. Their retardation is often caused by an accompanying neurological disorder. The profoundly retarded need a high level of structure and supervision.

The American Association on Mental Retardation (AAMR) has developed another widely accepted diagnostic classification system for mental retardation. The AAMR classification system focuses on the capabilities of the retarded individual rather than on the limitations. The categories describe the level of support required. They are: intermittent support, limited support, extensive support, and pervasive support. Intermittent support, for example, is support needed only occasionally, perhaps during times of stress or crisis. It is the type of support typically required for most mildly retarded individuals. At the other end of the spectrum, pervasive support, or life-long, daily support for most adaptive areas, would be required for profoundly retarded individuals.

Demographics

For children, the mental retardation rate is 11.4 per 1,000 and varies approximately nine fold, ranging from 3.2 in New Jersey to 31.4 in Alabama. For adults, the rate is 6.6 and varies approximately six fold, ranging from 2.5 in Alaska to 15.7 in West Virginia. In 42 states, the rate for children is higher than that for adults; in seven states, the rate for adults is higher, and in two states, both rates are similar. The correlation between state-specific rates for children and for adults is 0.66. Overall, 69 percent of the state-specific variation in prevalence rates for adults is accounted for by median household income, the percentage of total births to teenaged mothers, and the percentage of the population with less than a ninth-grade education. Low educational attainment was the most important correlate of mental retardation rates among adults.

Causes and Symptoms

Low IQ scores and limitations in adaptive skills are the hallmarks of mental retardation. Aggression, self-injury, and mood disorders are sometimes associated with the disability. The severity of the symptoms and the age at which they first appear depend on the cause. Children who are mentally retarded reach developmental milestones significantly later than expected, if at all. If retardation is caused by chromosomal or other genetic disorders, it is often apparent from infancy. If retardation is caused by childhood illnesses or injuries, learning and adaptive skills that were once easy may suddenly become difficult or impossible to master. In about 35 percent of cases, the cause of mental retardation cannot be found. Biological and environmental factors that can cause mental retardation include genetics, prenatal illnesses and issues, childhood illnesses and injuries, and environmental factors.

Genetics

About 5 percent of mental retardation is caused by hereditary factors. Mental retardation may be caused by an inherited abnormality of the genes, such as fragile X syndrome. Fragile X, a defect in the chromosome that determines sex, is the most common inherited cause of mental retardation. Single gene defects such as phenylketonuria (PKU) and other inborn errors of metabolism may also cause mental retardation if they are not found and treated early. An accident or mutation in genetic development may also cause retardation. Examples of such accidents are development of an extra chromosome 18 (trisomy 18) and Down syndrome. Down syndrome is caused by an abnormality in the development of chromosome 21. It is the most common genetic cause of mental retardation.

Prenatal Illnesses and Issues

Fetal alcohol syndrome affects one in 600 children in the United States. It is caused by excessive alcohol intake in the first twelve weeks (trimester) of pregnancy. Some studies have shown that even moderate alcohol use during pregnancy may cause learning disabilities in children. Drug abuse and cigarette smoking during pregnancy have also been linked to mental retardation.

Maternal infections and illnesses such as glandular disorders, rubella, toxoplasmosis, and cytomegalovirus infection may cause mental retardation. When the mother has high blood pressure (hypertension) or blood poisoning (toxemia), the flow of oxygen to the fetus may be reduced, causing brain damage and mental retardation.

Birth defects that cause physical deformities of the head, brain, and central nervous system frequently cause mental retardation. Neural tube defect, for example, is a birth defect in which the neural tube that forms the spinal cord does not close completely. This defect may cause children to develop an accumulation of cerebrospinal fluid on the brain (hydrocephalus). By putting pressure on the brain hydrocephalus can cause learning impairment.

Childhood Illnesses and Injuries

Hyperthyroidism, whooping cough, chickenpox, measles, and Hib disease (a bacterial infection) may cause mental retardation if they are not treated adequately. An infection of the membrane covering the brain (meningitis) or an inflammation of the brain itself (encephalitis) cause swelling that in turn may cause brain damage and mental retardation. Traumatic brain injury caused by a blow or a violent shake to the head may also cause brain damage and mental retardation in children.

Environmental Factors

Ignored or neglected infants who are not provided the mental and physical stimulation required for normal development may suffer irreversible learning impairments. Children who live in poverty and suffer from malnutrition, unhealthy living conditions, and improper or inadequate medical care are at a higher risk. Exposure to lead can also cause mental retardation. Many children develop lead poisoning by eating the flaking lead-based paint often found in older buildings.

When to Call the Doctor

If mental retardation is suspected, a comprehensive physical examination and medical history should be done immediately to discover any organic cause of symptoms. Conditions such as hyperthyroidism and PKU are treatable. If these conditions are discovered early, the progression of retardation can be stopped and, in some cases, partially reversed. If a neurological cause such as brain injury is suspected, the child may be referred to a neurologist or neuropsychologist for testing.

The symptoms of mental retardation are usually evident by a child's first or second year. In the case of Down syndrome, which involves distinctive physical characteristics, a diagnosis can usually be made shortly after birth. Mentally retarded children lag behind their peers in developmental milestones such as smiling, sitting up, walking, and talking. They often demonstrate lower than normal levels of interest in their environment and responsiveness to others, and they are slower than other children in reacting to visual or auditory stimulation. By the time a child reaches the age of two or three, retardation can be determined using physical and psychological tests. Testing is important at this age if a child shows signs of possible retardation because alternate causes, such as impaired hearing, may be found and treated.

Diagnosis

A complete medical, family, social, and educational history is compiled from existing medical and school records (if applicable) and from interviews with parents. Children are given intelligence tests to measure their learning abilities and intellectual functioning. Such tests include the Stanford-Binet Intelligence Scale, the Wechsler Intelligence Scales, the Wechsler Preschool and Primary Scale of Intelligence, and the Kaufmann Assessment Battery for Children. For infants, the Bayley Scales of Infant Development may be used to assess motor, language, and problem-solving skills. Interviews with parents or other caregivers are used to assess the child's daily living, muscle control, communication, and social skills. The Woodcock-Johnson Scales of Independent Behavior and the Vineland Adaptive Behavior Scale (VABS) are frequently used to test these skills.

Treatment

Federal legislation entitles mentally retarded children to free testing and appropriate, individualized education and skills training within the school system from ages three to 21. For children under the age of three, many states have established early intervention programs that assess, recommend, and begin treatment programs. Many day schools are available to help train retarded children in basic skills such as bathing and feeding themselves. Extracurricular activities and social programs are also important in helping retarded children and adolescents gain self-esteem.

Training in independent living and job skills is often begun in early adulthood. The level of training depends on the degree of retardation. Mildly retarded individuals can often acquire the skills needed to live independently and hold an outside job. Moderate to profoundly retarded individuals usually require supervised community living. Family therapy can help relatives of the mentally retarded develop coping skills. It can also help parents deal with feelings of guilt or anger. A supportive, warm home environment is essential to help the mentally retarded reach their full potential. However, as of 2004, there is no cure for mental retardation.

A promising but controversial treatment for mental retardation involves stem cell research. In the early 2000s scientists are exploring the potential of adult stem cells in treating mental retardation. They have transplanted bone marrow cells into living embryos in the uteri of animals to approach congenital diseases, birth defects, and mental retardation. Stem cells are primitive cells that are capable of forming diverse types of tissue. Because of this remarkable quality, human stem cells hold huge promise for the development of therapies to regenerate damaged organs and heal people who are suffering from terrible diseases. Embryonic stem cells are derived from human embryos. Their use is controversial because such stem cells cannot be used in research without destroying the living embryo. Other sources of stem cells are available, however, and can be harvested from umbilical cord blood as well as from fat, bone marrow, and other adult tissue without harm to the donor. An enormous amount of research involving adult stem cells is going on as of 2004 in laboratories in the United States.

Prognosis

Individuals with mild to moderate mental retardation are frequently able to achieve some self-sufficiency and to lead happy and fulfilling lives. To reach these goals, they need appropriate and consistent educational, community, social, family, and vocational supports. The outlook is less promising for those with severe to profound retardation. Studies have shown that these individuals have a shortened life expectancy. The diseases that are usually associated with severe retardation may cause the shorter life span. People with Down syndrome develop in later life the brain changes that characterize Alzheimer's disease and may develop the clinical symptoms of this disease as well.

Prevention

Immunization against diseases such as measles and Hib prevents many of the illnesses that can cause mental retardation. In addition, all children should undergo routine developmental screening as part of their pediatric care. Screening is particularly critical for those children who may be neglected or undernourished or may live in disease-producing conditions. Newborn screening and immediate treatment for PKU and hyperthyroidism can usually catch these disorders early enough to prevent retardation. Good prenatal care can also help prevent retardation. Pregnant women should be educated about the risks of drinking and the need to maintain good nutrition during pregnancy. Tests such as amniocentesis and ultrasonography can determine whether a fetus is developing normally in the womb.

Parental Concerns

All states are required by law to offer early intervention programs for mentally retarded children from the time they are born. The sooner the diagnosis of mental retardation is made, the more the child can be helped. With mentally retarded infants, the treatment emphasis is on sensorimotor development, which can be stimulated by exercises and special types of play. It is required that special education programs be available for retarded children starting at three years of age. These programs concentrate on essential self-care, such as feeding, dressing, and toilet training. There is also specialized help available for language and communication difficulties and physical disabilities. As children grow older, training in daily living skills, as well as academic subjects, is offered.

Counseling and therapy are another important type of treatment for the mentally retarded. Retarded children are prone to behavioral problems caused by short attention span, low tolerance for frustration, and poor impulse control. Behavior therapy with a mental health professional can help combat negative behavior patterns and replace them with more functional ones. A counselor or therapist can also help retarded children cope with the low self-esteem that often results from the realization that they are different from other children, including siblings. Counseling can also be valuable for the family of a retarded child to help parents cope with painful feelings about the child's condition and with the extra time and patience needed for the care and education of a special-needs child. Siblings may need to talk about the pressures they face, such as accepting the extra time and attention their parents must devote to a retarded brother or sister. Sometimes parents have trouble bonding with an infant who is retarded and need professional help and reassurance to establish a close and loving relationship.

Current social and healthcare policies encourage keeping mentally retarded persons in their own homes or in informal group home settings rather than institutions. The variety of social and mental health services available to the mentally retarded, including pre-vocational and vocational training, are geared toward making this possible.

Resources

Books

Ainsworth, Patricia, and Pamela Baker. Understanding Mental Retardation. Jackson, MS: University Press of Mississippi, 2004.

Libal, Autumn. My Name Is Not Slow: Youth with Mental Retardation. Broomall, PA: Mason Crest Publishers, 2004.

Wehmeyer, Michael L., et al. Teaching Students with Mental Retardation: Providing Access to the General Curriculum. Baltimore: Brookes Publishing Co., 2001.

Periodicals

Cinamon, Rachel Gali, and Limor Gifsh. "Conceptions of Work among Adolescents and Young Adults with Mental Retardation." Career Development Quarterly 52 (March 2004): 212–24.

Howard, Barbara J. "Mental Retardation Challenges." Pediatric News 38 (September 2004): 20–1.

Kerker, Bonnie D., et al. "Mental Health Disorders among Individuals with Mental Retardation: Challenges to Accurate Prevalence Estimates." Public Health Reports 119 (August 2004): 409–17.

Ly, Tran M., and Robert M. Hodapp. "Maternal Attribution of Child Noncompliance in Children with Mental Retardation: Down Syndrome versus Other Causes." Journal of Developmental & Behavioral Pediatrics 23 (October 2002): 322–29.

Organizations

American Association on Mental Retardation. 444 North Capitol Street NW, Suite 846, Washington, DC 20001–1512. Web site: www.aamr.org.

National Academy of Child & Adolescent Psychiatry. 3615 Wisconsin Ave. NW, Washington, DC 20016. Web site: www.aacap.org.

Web Sites

"Introduction to Mental Retardation." The Arc, 2004. Available online at www.thearc.org/faqs/mrqa.html (accessed November 11, 2004).

"Mental Retardation." National Dissemination Center for Children with Disabilities, January 2004. Available online at www.nichcy.org/pubs/factshe/fs8txt.htm (accessed November 11, 2004).

"Morbidity and Mortality Weekly Report." Centers for Disease Control and Prevention, January 26, 1996. Available online at www.cdc/mmwr/preview/mmwrhtml/00040023.htm (accessed November 11, 2004).

[Article by: Paula Anne Ford-Martin Ken R. Wells]

The term "mental retardation" refers to persons with deficits in both their intellectual and adaptive (everyday) functioning. These individuals typically show IQ scores below 70, as well as difficulties in meeting the demands of everyday living, whether it be in communicating and socializing with others or attending to grooming and domestic chores. Mental retardation manifests itself in the developmental years, before age eighteen.

Anywhere from 1 to 3 percent of the population is estimated to be mentally retarded. The majority of these persons (about 85 percent), show mild levels of delay, with IQs ranging from 55 to 70. Approximately 10 percent show moderate delays, with IQs from 40 to 55. With proper supports, individuals with mild to moderate mental retardation successfully live and work in their communities, or in supervised settings such as group homes. The remainder of persons show severe to profound levels of mental retardation (IQs of 40 and below), and many of these individuals have sensory, motor, or medical problems that further complicate their care.

Mental retardation has multiple causes. Approximately 50 percent of persons with mental retardation do not have a clear-cut organic or biological cause for their delay. The low IQ of these persons is likely due to a combination of environmental and genetic factors. The other 50 percent of persons with mental retardation have a known biological etiology. These include prenatal causes such as genetic disorders or alcohol exposure in utero; perinatal causes such as premature birth; and postnatal causes such as head trauma and exposure to lead.

There are now over 750 known genetic disorders that cause mental retardation, accounting for about half of those with organic etiologies. Some of these can be screened for during pregnancy—including Down syndrome, the most common chromosomal cause of mental retardation. Other disorders include fragile X syndrome, Prader-Willi syndrome, and Williams syndrome. People with these and other syndromes often show distinctive personalities, behavioral problems, and intellectual strengths and weaknesses that can be used to guide their care.

Some organic causes of mental retardation can be prevented. As many as two in one thousand children are born with fetal alcohol syndrome, which is prevented by refraining from drinking alcohol during pregnancy. Babies born with phenylketonuria, or PKU, are placed on a special, phenylalanine-reduced diet, thereby avoiding the severe mental retardation that otherwise characterizes this disorder.

People with mental retardation are at higher risk than those in the general population for behavioral and psychiatric problems such as autism, hyperactivity, and self-injurious behaviors. Throughout the early to mid-1900s, many of these individuals, as well as those without behavioral problems, were placed in large institutions. Since the advent of deinstitutionalization in the 1960s, most children with mental retardation have been cared for by their families. To improve the quality of life for these children, the Americans with Disabilities Act and other federal legislation emphasize community inclusion and specialized services such as early intervention, special education, and school-to-work transition. Many individuals also benefit from occupational, physical, and speech-language therapies, as well as from programs that teach daily living skills. With proper support, most people with mental retardation successfully live, work, and play in their communities.

(SEE ALSO: Fetal Alcohol Syndrome; Genetics and Health; Medical Genetics; Mental Health; Phenylketonuria)

Bibliography

Arc of the United States. "Information about Mental Retardation and Related Topics." Available at http://www.thearc.org.

Dykens, E. M. (2000). "Psychopathology in Children with Intellectual Disabilities." Journal of Child Psychology and Psychiatry 41:407–417.

Dykens, E. M.; Hodapp, R. M.; and Finucane, B. M. (2000). Genetics and Mental Retardation Syndromes: A New Look at Behavior and Intervention. Baltimore, MD: Paul H. Brookes.

Hodapp, R. M., and Dykens, E. M. (1996). "The Child with Mental Retardation." In Child Psychopathology, eds. E. J. Mash and R. A. Barkley. New York: Gilford Press.

King, B. H.; Hodapp, R. M.; and Dykens, E. M. (2000). "Mental Retardation." In Comprehensive Textbook of Psychiatry, 7th edition, eds. H. I. Kaplan and B. J. Sadock. New York: Williams & Wilkins.

— ELISABETH M. DYKENS

For more information on intellectual disability, visit Britannica.com.

Mental retardation
Classification and external resources
ICD-10	F70.-F79.
ICD-9	317-319
DiseasesDB	4509
eMedicine	med/3095  neuro/605
MeSH	D008607

Mental retardation is a generalized disorder, characterized by subaverage cognitive functioning and deficits in two or more adaptive behaviors with onset before the age of 18. Once focused almost entirely on cognition, the definition now includes both a component relating to mental functioning and one relating to individuals' functional skills in their environment.

Contents 1 Alternative terms 2 Signs 3 Diagnosis 3.1 IQ below 70 3.2 Significant limitations in two or more areas of adaptive behavior 3.3 Evidence that the limitations became apparent in childhood 4 Causes 5 Treatment and assistance 6 Archaic terms 7 References 8 External links

Alternative terms

The term "mental retardation" is a diagnostic term designed to capture and standardize a group of disconnected categories of mental functioning such as "idiot", "imbecile", and "moron" derived from early IQ tests, which acquired pejorative connotations in popular discourse over time. The term "mental retardation" has itself now acquired some pejorative and shameful connotations over the last few decades due to the use of "retarded" as an insult. This may in turn have contributed to its replacement with expressions such as "mentally challenged" or "intellectual disability". While "developmental disability" may be considered to subsume other disorders (see below), "developmental disability" or "developmental delay" (for children under age 18), are generally considered more acceptable terms than "mental retardation" among members of the disability community.

• In North America mental retardation is subsumed into the broader term developmental disability, which also includes epilepsy, autism, cerebral palsy and other disorders that develop during the developmental period (birth to age 18.) Because service provision is tied to the designation developmental disability, it is used by many parents, direct support professionals, and physicians. However, in school-based settings, the more specific term mental retardation is still typically used, and is one of 13 categories of disability under which children may be identified for special education services under Public Law 108-446.
• The phrase intellectual disability is increasingly being used as a synonym for people with significantly below-average cognitive ability.^[1] These terms are sometimes used as a means of separating general intellectual limitations from specific, limited deficits as well as indicating that it is not an emotional or psychological disability. Intellectual disability may also used to describe the outcome of traumatic brain injury or lead poisoning or dementing conditions such as Alzheimer's disease. It is not specific to congenital disorders such as Down syndrome.

The American Association on Mental Retardation continued to use the term mental retardation until 2006.^[2] In June 2006 its members voted to change the name of the organization to the "American Association on Intellectual and Developmental Disabilities," rejecting the options to become the AAID or AADD. Part of the rationale for the double name was that many members worked with people with pervasive developmental disorders, most of whom do not have mental retardation.^[3]

In the UK, "mental handicap" had become the common medical term, replacing "mental subnormality" in Scotland and "mental deficiency" in England and Wales, until Stephen Dorrell, Secretary of State for Health for the United Kingdom from 1995-7, changed the NHS's designation to "learning disability." The new term is not yet widely understood, and is often taken to refer to problems affecting schoolwork (the American usage), which are known in the UK as "learning difficulties." British social workers may use "learning difficulty" to refer to both people with MR and those with conditions such as dyslexia.

In England and Wales between 1983 and 2008 the Mental Health Act 1983 defined "mental impairment" and "severe mental impairment" as "a state of arrested or incomplete development of mind which includes significant/severe impairment of intelligence and social functioning and is associated with abnormally aggressive or seriously irresponsible conduct on the part of the person concerned."^[4] As behavior was involved, these were not necessarily permanent conditions: they were defined for the purpose of authorising detention in hospital or guardianship. The term Mental Impairment was removed from the Act in November 2008, but the grounds for detention remained. However, English statute law uses "mental impairment" elsewhere in a less well-defined manner—e.g. to allow exemption from taxes—implying that mental retardation without any behavioural problems is what is meant.

Signs

Children with mental retardation may learn to sit up, to crawl, or to walk later than other children, or they may learn to talk later. Both adults and children with mental retardation may also exhibit the following characteristics:

• Delays in oral language development
• Deficits in memory skills
• Difficulty learning social rules
• Difficulty with problem solving skills
• Delays in the development of adaptive behaviors such as self-help or self-care skills
• Lack of social inhibitors

The limitations of cognitive functioning will cause a child with mental retardation to learn and develop more slowly than a typical child. Children may take longer to learn language, develop social skills, and take care of their personal needs such as dressing or eating. Learning will take them longer, require more repetition, and skills may need to be adapted to their learning level. Nevertheless, virtually every child is able to learn, develop and become participating members of the community.

In early childhood mild mental retardation (IQ 60–70) may not be obvious, and may not be identified until children begin school. Even when poor academic performance is recognized, it may take expert assessment to distinguish mild mental retardation from learning disability or emotional/behavioral disorders. As individuals with mild mental retardation reach adulthood, many learn to live independently and maintain gainful employment.

Moderate mental retardation (IQ 50–60) is nearly always apparent within the first years of life. Children with moderate mental retardation will require considerable supports in school, at home, and in the community in order to participate fully. As adults they may live with their parents, in a supportive group home, or even semi-independently with significant supportive services to help them, for example, manage their finances.

A person with a more severe mental retardation will need more intensive support and supervision his or her entire life.

Diagnosis

According to the latest edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV),^[5] three criteria must be met for a diagnosis of mental retardation: an IQ below 70, significant limitations in two or more areas of adaptive behavior (as measured by an adaptive behavior rating scale, i.e. communication, self-help skills, interpersonal skills, and more), and evidence that the limitations became apparent before the age of 18.

It is formally diagnosed by professional assessment of intelligence and adaptive behavior.

IQ below 70

The first English-language IQ test, the Terman-Binet, was adapted from an instrument used to measure potential to achieve developed by Binet in France. Terman translated the test and employed it as a means to measure intellectual capacity based on oral language, vocabulary, numerical reasoning, memory, motor speed and analysis skills. The mean score on the currently available IQ tests is 100, with a standard deviation of 15 (WAIS/WISC-IV) or 16 (Stanford-Binet). Sub-average intelligence is generally considered to be present when an individual scores two standard deviatons below the test mean. Factors other than cognitive ability (depression, anxiety, etc.) can contribute to low IQ scores; it is important for the evaluator to rule them out prior to concluding that measured IQ is "significantly below average".

The following ranges, based on Standard Scores of intelligence tests, reflect the categories of the American Association of Mental Retardation, the Diagnostic and Statistical Manual of Mental Disorders-IV-TR, and the International Classification of Diseases-10:

Class	IQ
Profound mental retardation	Below 20
Severe mental retardation	20–34
Moderate mental retardation	35–49
Mild mental retardation	50–69
Borderline intellectual functioning	70–79

Since the diagnosis is not based only on IQ scores, but must also take into consideration a person's adaptive functioning, the diagnosis is not made rigidly. It encompasses intellectual scores, adaptive functioning scores from an adaptive behavior rating scale based on descriptions of known abilities provided by someone familiar with the person, and also the observations of the assessment examiner who is able to find out directly from the person what he or she can understand, communicate, and the like.

Significant limitations in two or more areas of adaptive behavior

Adaptive behavior, or adaptive functioning, refers to the skills needed to live independently (or at the minimally acceptable level for age). To assess adaptive behavior, professionals compare the functional abilities of a child to those of other children of similar age. To measure adaptive behavior, professionals use structured interviews, with which they systematically elicit information about persons' functioning in the community from people who know them well. There are many adaptive behavior scales, and accurate assessment of the quality of someone's adaptive behavior requires clinical judgment as well. Certain skills are important to adaptive behavior, such as:

• daily living skills, such as getting dressed, using the bathroom, and feeding oneself;
• communication skills, such as understanding what is said and being able to answer;
• social skills with peers, family members, spouses, adults, and others.

Evidence that the limitations became apparent in childhood

This third condition is used to distinguish it from dementing conditions such as Alzheimer's disease or due to traumatic injuries with attendant brain damage.

Causes

Down syndrome, fetal alcohol syndrome and Fragile X syndrome are the three most common inborn causes. However, doctors have found many other causes. The most common are:

• Genetic conditions. Sometimes disability is caused by abnormal genes inherited from parents, errors when genes combine, or other reasons. The most prevalent genetic conditions include Down syndrome, Klinefelter's syndrome, Fragile X syndrome, Neurofibromatosis, congenital hypothyroidism, Williams syndrome, Phenylketonuria (PKU), and Prader-Willi syndrome. Other genetic conditions include Phelan-McDermid syndrome (22q13del), Mowat-Wilson syndrome, genetic ciliopathy^[6]. In the rarest of cases, abnormalities with the X or Y chromosome may also cause disability. 48, XXXX and 49, XXXXX syndrome affect a small number of girls worldwide, while boys may be affected by 47, XYY, 49, XXXXY, or 49, XYYYY.
• Problems during pregnancy. Mental disability can result when the fetus does not develop properly. For example, there may be a problem with the way the fetus' cells divide as it grows. A woman who drinks alcohol (see fetal alcohol syndrome) or gets an infection like rubella during pregnancy may also have a baby with mental disability.
• Problems at birth. If a baby has problems during labor and birth, such as not getting enough oxygen, he or she may have developmental disability due to brain damage.
• Exposure to certain types of disease or toxins. Diseases like whooping cough, measles, or meningitis can cause mental disability if medical care is delayed or inadequate. Exposure to poisons like lead or mercury may also affect mental ability.
• Iodine deficiency, affecting approximately 2 billion people worldwide, is the leading preventable cause of mental disability in areas of the developing world where iodine deficiency is endemic. Iodine deficiency also causes goiter, an enlargement of the thyroid gland. More common than full-fledged cretinism, as retardation caused by severe iodine deficiency is called, is mild impairment of intelligence. Certain areas of the world due to natural deficiency and governmental inaction are severely affected. India is the most outstanding, with 500 million suffering from deficiency, 54 million from goiter, and 2 million from cretinism. Among other nations affected by iodine deficiency, China and Kazakhstan have begun taking action, whereas Russia has not.^[7]
• Malnutrition is a common cause of reduced intelligence in parts of the world affected by famine, such as Ethiopia.^[8]

Treatment and assistance

By most definitions mental retardation is more accurately considered a disability rather than a disease. MR can be distinguished in many ways from mental illness, such as schizophrenia or depression. Currently, there is no "cure" for an established disability, though with appropriate support and teaching, most individuals can learn to do many things.

There are thousands of agencies in the United States that provide assistance for people with developmental disabilities. They include state-run, for-profit, and non-profit, privately run agencies. Within one agency there could be departments that include fully staffed residential homes, day habilitation programs that approximate schools, workshops wherein people with disabilities can obtain jobs, programs that assist people with developmental disabilities in obtaining jobs in the community, programs that provide support for people with developmental disabilities who have their own apartments, programs that assist them with raising their children, and many more. The Burton Blatt Institute at Syracuse University works to advance the civic, economic, and social participation of people with disabilities. There are also many agencies and programs for parents of children with developmental disabilities.

Although there is no specific medication for mental retardation, many people with developmental disabilities have further medical complications and may take several medications. Beyond that there are specific programs that people with developmental disabilities can take part in wherein they learn basic life skills. These "goals" may take a much longer amount of time for them to accomplish, but the ultimate goal is independence. This may be anything from independence in tooth brushing to an independent residence. People with developmental disabilities learn throughout their lives and can obtain many new skills even late in life with the help of their families, caregivers, clinicians and the people who coordinate the efforts of all of these people.

Archaic terms

Several traditional terms denoting varying degrees of mental deficiency long predate psychiatry, but have since been subject to the euphemism treadmill. In common usage they are simple forms of abuse. Their now-obsolete use as psychiatric technical definitions is of purely historical interest. They are often encountered in old documents such as books, academic papers, and census forms (for example, the British census of 1901 has a column heading including the terms imbecile and feeble-minded).

There have been some efforts made among mental health professionals to discourage use of these terms. Nevertheless their use persists. In addition to the terms below, the abbreviation retard or tard is still used as a generic insult. A BBC survey in 2003 ranked retard as the most offensive disability-related word, ahead of terms such as spastic (not considered offensive in America^[9]) and mong.^[10]

• Cretin is the oldest and comes from a dialectal French word for Christian.^[11] The implication was that people with significant intellectual or developmental disabilities were "still human" (or "still Christian") and deserved to be treated with basic human dignity. This term has not been used in any serious or scientific endeavor since the middle of the 20th century and is now always considered a term of abuse: notably, in the 1964 movie Becket, King Henry II calls his son and heir a "cretin." "Cretinism" is also used as an obsolescent term to refer to the condition of congenital hypothyroidism, in which there is some degree of mental retardation.
• Amentia has a long history, mostly associated with dementia. The difference between amentia and dementia was originally defined by time of onset. Amentia was the term used to describe an individual who developed deficits in mental functioning early in life, while dementia described individuals who develop mental deficiencies as adults. During the 1890s, amentia was used to describe someone who was born with mental deficiencies. By 1912, ament was a classification lumping "idiots, imbeciles, and feeble minded" individuals in a category separate from a dement classification, in which the onset is later in life.^[12]
• Dementia appears to be unique in that it seems to have gone unchanged in terms of meaning over hundreds of years. The term first emerged in the sixteenth century and was used in reference to people who lost mental functioning. In 1912, the classification of dement was used to identify individuals who had previously functioned normally, but who lost their faculties over time. Today's definition has pinpointed the onset of mental deterioration as occurring after the age of eighteen.^[12]
• Idiot indicated the greatest degree of intellectual disability, where the mental age is two years or less, and the person cannot guard himself or herself against common physical dangers. The term was gradually replaced by the term profound mental retardation.
• Imbecile indicated an intellectual disability less extreme than idiocy and not necessarily inherited. It is now usually subdivided into two categories, known as severe mental retardation and moderate mental retardation.
• Moron was defined by the American Association for the Study of the Feeble-minded in 1910, following work by Henry H. Goddard, as the term for an adult with a mental age between eight and twelve; mild mental retardation is now the term for this condition. Alternative definitions of these terms based on IQ were also used. This group was known in UK law from 1911 to 1959/60 as "feeble-minded".
• Mongolism was a medical term used to identify someone with Down syndrome. For obvious reasons, the Mongolian People's Republic requested that the medical community cease use of the term as a description of mental retardation. Their request was granted in the 1960s, when the World Health Organization agreed that the term should cease being used within the medical community.^[12]
• In the field of special education, educable (or "educable mentally retarded") refers to MR students with IQs of approximately 50-75 who can progress academically to a late elementary level. Trainable (or "trainable mentally retarded") refers to students whose IQs fall below 50 but who are still capable of learning personal hygiene and other living skills in a sheltered setting, such as a group home. In many areas, these terms have fallen out of favor in favor of "severe" and "moderate" mental retardation. While the names change, the meaning stays roughly the same in practice.
• Retarded comes from the Latin retardare, "to make slow, delay, keep back, or hinder." The term was recorded in 1426 as a "fact or action of making slower in movement or time." The first record of retarded in relation to being mentally slow was in 1895. The term retarded was used to replace terms like idiot, moron, and imbecile because it was not a derogatory term. By the 1960s, however, the term had taken on a partially derogatory meaning as well.^[12]

Perhaps the negative connotations associated with these numerous terms for mental retardation reflect society's ambivalent attitude about the condition. There are competing desires among elements of society, some of whom seek neutral medical terms, and others who want to use such terms as weapons with which to abuse people.^[12]

Today, the term "retarded" is slowly being replaced by new words like "special" or "challenged." The term "developmental delay" is rapidly gaining popularity among caretakers and parents of individuals with mental retardation. Using the word "delay" is preferred over "disability" by many people, because that term (delay) encapsulates the core deficit that creates mental retardation in the first place. Delay suggests that a person has been held back from their potential, rather than someone who has been disabled.

Usage has changed over the years, and differed from country to country, which needs to be borne in mind when looking at older books and papers. For example, "mental retardation" in some contexts covers the whole field, but previously applied to what is now the mild MR group. "Feeble-minded" used to mean mild MR in the UK, and once applied in the US to the whole field. "Borderline MR" is not currently defined, but the term may be used to apply to people with IQs in the 70s. People with IQs of 70 to 85 used to be eligible for special consideration in the US public education system on grounds of mental retardation.

Along with the changes in terminology, and the downward drift in acceptability of the old terms, institutions of all kinds have had to repeatedly change their names. This affects the names of schools, hospitals, societies, government departments, and academic journals. For example, the Midlands Institute of Mental Subnormality became the British Institute of Mental Handicap and is now the British Institute of Learning Disability. This phenomenon is shared with mental health and motor disabilities, and seen to a lesser degree in sensory disabilities.

References

1. ^ MENCAP: Website of the UK's leading learning disability charity. Retrieved 28 June 2006
2. ^ "AAIDD POSITION STATEMENTS". http://www.aamr.org/Policies/faq_mental_retardation.shtml. Retrieved on 2007-08-23. 
3. ^ Chakrabarti S,Fombonne E (2001). "Pervasive developmental disorders in preschool children". JAMA 285 (24): 3093–9. doi:10.1001/jama.285.24.3093. PMID 11427137. http://jama.ama-assn.org/cgi/content/full/285/24/3093. 
4. ^ "DRAFT ILLUSTRATIVE CODE OF PRACTICE". http://www.rcpsych.ac.uk/PDF/Draft%20Illustrative%20Code%20of%20Practice%20July%202007.pdf. Retrieved on 2007-08-23. 
5. ^ "eMedicine - Mental Retardation : Article by C Simon Sebastian, MD". http://www.emedicine.com/med/topic3095.htm. Retrieved on 2007-08-23. 
6. ^ Badano, Jose L.; Norimasa Mitsuma, Phil L. Beales, Nicholas Katsanis (September 2006). "The Ciliopathies : An Emerging Class of Human Genetic Disorders". Annual Review of Genomics and Human Genetics 7: 125–148. doi:10.1146/annurev.genom.7.080505.115610. http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.genom.7.080505.115610. Retrieved on 2008-06-15. 
7. ^ "In Raising the World’s I.Q., the Secret’s in the Salt", article by Donald G. McNeil, Jr., December 16, 2006, New York Times
8. ^ "Malnutrition Is Cheating Its Survivors, and Africa’s Future" article in the New York Times by Michael Wines, December 28, 2006
9. ^ spastic, learning disability. Murphy, M Lynne. 2007-02-28. Retrieved 2008-01-09.
10. ^ BBC (2003). "Worst Word Vote" (HTML). Ouch. http://www.bbc.co.uk/ouch/yourspace/worstwords/. Retrieved on 2007-08-17. 
11. ^ "cretin" (HTML). The American Heritage Dictionary of the English Language, Fourth Edition. Houghton Mifflin Company. 2006. http://dictionary.reference.com/browse/cretin. Retrieved on 2008-08-04. 
12. ^ ^{a b c d e} https://www.mhcinc.org/poc/view_doc.php?type=doc&id=10352

External links

Look up Retard in Wiktionary, the free dictionary.

• Mental Retardation Research Center
• National Center on Birth Defects and Developmental Disabilities
• The Arc
• Special Olympics
• Mental Health Care,Inc.

v • d • e WHO ICD-10 mental and behavioral disorders (F · 290–319) Neurological/symptomatic Dementia (Alzheimer's disease, multi-infarct dementia, Pick's disease, Creutzfeldt–Jakob disease, Huntington's disease, Parkinson's disease, AIDS dementia complex, Frontotemporal dementia, Elopement, Sundowning, Wandering) · Delirium · Post-concussion syndrome · Organic brain syndrome Psychoactive substance alcohol (acute alcohol intoxication, drunkenness, alcohol dependence, alcoholic hallucinosis, Alcohol withdrawal, delirium tremens, Korsakoff's syndrome, alcohol abuse) · opioids (opioid overdose, opioid dependency) · sedative/hypnotic (benzodiazepine overdose, benzodiazepine dependence, benzodiazepine withdrawal) · cocaine (cocaine dependence) · general (Intoxication/Drug overdose, Drug abuse, Physical dependence, Rebound effect, Withdrawal) Schizophrenia, schizotypal and delusional Psychosis (Schizoaffective disorder, Schizophreniform disorder, Brief reactive psychosis) · Schizophrenia (Disorganized schizophrenia, Delusional disorder, Folie à deux) · Personality disorder (Schizotypal personality disorder) Mood (affective) Mania · Bipolar disorder (Bipolar I, Bipolar II, Cyclothymia) · Depression (Major depressive disorder, Dysthymia, Seasonal affective disorder) Neurotic, stress-related and somatoform Anxiety disorder/ adjustment disorder phobic anxiety disorders: Agoraphobia · Social anxiety/Social phobia (Anthropophobia) · Specific phobia (Claustrophobia) Panic disorder/Panic attack · Generalized anxiety disorder · OCD · stress (Acute stress reaction, PTSD) Somatoform disorder Somatization disorder · Body dysmorphic disorder · Hypochondriasis · Nosophobia · Da Costa's syndrome · Psychalgia · Conversion disorder (Ganser syndrome, Globus pharyngis) · Neurasthenia Dissociative disorder Dissociative identity disorder · Psychogenic amnesia Physiological/physical behavioral Eating disorder Anorexia nervosa · Bulimia nervosa Sleep disorder Dyssomnia (Hypersomnia, Insomnia) · Parasomnia (REM behavior disorder, Night terror) · Nightmare Sexual dysfunction Erectile dysfunction · Premature ejaculation · Vaginismus · Dyspareunia · Hypersexuality · Female sexual arousal disorder Postnatal Postpartum depression · Postnatal psychosis Adult personality and behavior Personality disorder · Impulse control disorder (Kleptomania, Trichotillomania, Pyromania) · Factitious disorder (Munchausen syndrome) · Ego-dystonic sexual orientation · Paraphilia (Voyeurism, Fetishism) Mental disorders diagnosed in childhood Mental retardation X-Linked mental retardation Psychological development (developmental disorder) Specific speech and language (expressive language disorder, aphasia, expressive aphasia, receptive aphasia, Landau–Kleffner syndrome, lisp) · Scholastic skills (dyslexia, dysgraphia, Gerstmann syndrome) · Motor function (developmental dyspraxia) Pervasive Autism · Rett syndrome · Asperger syndrome Behavioral and emotional ADHD · Conduct disorder (ODD) · emotional disorder (Separation anxiety disorder) · social functioning (Selective mutism, RAD, DAD) · Tic disorder (Tourette syndrome) · Speech (Stuttering, Cluttering) · Stereotypic movement disorder

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