Mental Retardation
Below-average intellectual functioning abilities as determined by intelligence quotient (IQ) testing, and low adaptive functioning at home or in a work environment. An individual is considered to have mental retardation if IQ is below 70-75, there are significant limitations in two or more adaptive skill areas, and the condition is present from childhood.
Between 6.2 million and 7.5 million people have mental retardation, which is 10 times more common than CEREBRAL PALSY and 28 times more prevalent than neural tube defects such as SPINA BIFIDA. Mental retardation cuts across the lines of racial, ethnic, educational, social, and economic backgrounds, so that one out of 10 American families is directly affected by mental retardation.
The effects of mental retardation vary considerably among people, just as the range of abilities varies considerably among people who do not have mental retardation. About 87 percent will be mildly affected and will be only a little slower than average in learning new information and skills. As children, their mental retardation is not easy to see and may not be identified until school age. The remaining 13 percent of people with mental retardation (those with IQs under 50) will have serious limits in function. However, with early intervention, a good education, and appropriate supports as an adult, all can lead satisfying lives in the community.
People with mental retardation may have trouble communicating, interacting with others, and being independent. There may also be concerns with regard to understanding health and safety issues. Not all skills are necessarily impaired, and children with mental retardation may learn to function independently in many areas. However, education programs, providing skilled assistance and ongoing support, are necessary for determining appropriate living and work environments.
Symptoms
Most parents tend to notice a problem within the first year or two of life. While all children develop different skills at different times, significant lags in several areas of development are an early warning sign. Children with mental retardation tend to reach developmental milestones later than youngsters of normal intelligence. They may not learn to sit, crawl, or walk until well after their second birthdays. Speech is likewise delayed, and some severely retarded children never learn to talk at all.
Cause
Mental retardation can be caused by any condition that impairs development of the brain before birth, during birth, or in the childhood years. Several hundred causes have been discovered, but about a third of the time the reason remains unknown. The three most common known causes of mental retardation are DOWN SYNDROME, FETAL ALCOHOL SYNDROME, and FRAGILE X SYNDROME.
Genetic conditions These conditions are caused by abnormal genes or from other disorders of the genes caused during pregnancy by infections, overexposure to X rays, and other factors. More than 500 genetic diseases are associated with mental retardation, such as:
• PKU (PHENYLKETONURIA) A single gene disorder caused by a defective enzyme
• Down syndrome A chromosomal disorder that happens sporadically, caused by too many chromosomes, or by a change in structure of a chromosome
• Fragile X syndrome A single gene disorder located on the X chromosome that is the leading inherited cause of mental retardation
Prenatal problems Using alcohol, drugs, or smoking during pregnancy can cause mental retardation. Other risks include malnutrition, certain environmental contaminants, and illnesses of the mother during pregnancy, such as TOXOPLASMOSIS, CYTOMEGALOVIRUS, GERMAN MEASLES, and SYPHILIS. Pregnant women who are infected with HIV and HERPES may pass the virus to their child, leading to future neurological damage.
Problems at birth Although any unusual stress during birth may injure the infant’s brain, prematurity and low birth weight are more likely to predict serious problems than any other conditions.
Problems after birth Childhood diseases such as WHOOPING COUGH, CHICKEN POX, MEASLES, and HIB disease (which may lead to MENINGITIS and ENCEPHALITIS) can damage the brain, as can accidents such as a blow to the head or near drowning. Lead, mercury, and other environmental toxins can cause irreparable damage to the brain and nervous system.
Socioeconomic Children in poor families may become mentally retarded because of malnutrition, disease-producing conditions, inadequate medical care, and environmental health hazards. Also, children in disadvantaged areas may be deprived of many common cultural and day-to-day experiences provided to other youngsters. Research suggests that such under-stimulation can result in irreversible damage and can serve as a cause of mental retardation.
Diagnosis
Mental retardation is diagnosed primarily on the basis of intelligence testing, but affected children often demonstrate other brain problems such as attention deficits, movement problems, and perceptual difficulties. Dexterity and coordination also may be limited. If the child’s doctor suspects a problem, parents may be referred to a psychologist or other mental health expert, who can administer a number of special tests, including standardized intelligence tests and a standardized adaptive skills test. Next, an expert should describe the child’s strengths and weaknesses in intellectual and adaptive behavior skills, emotions, physical health, and environment. These skills can be assessed by formal testing, observations, interviews, and interacting with the child in daily life.
Intelligence testing alone is only one measure of functioning ability, however. A child with limits in intellectual functioning who does not have limits in adaptive skill areas may not be diagnosed as having mental retardation. “Adaptive skill areas” are those daily living skills needed to live, work, and play in the community and include communication, self-care, home living, social skills, leisure, health and safety, self-direction, functional academics (reading, writing, basic math), community use, and work. Adaptive skills are assessed in the child’s typical environment.
Careful assessment is important because many children have been misdiagnosed with mental retardation, particularly at a young age, and are later diagnosed with profound learning disabilities but with average or above average intelligence.
Types of Mental Retardation
Individuals with mental retardation are not a homogenous group but have widely differing levels of functioning. While the term mental retardation still exists as a clinical diagnosis, experts today prefer terms such as developmental disability, which some believe does not carry the same negative connotations. In the past, those who were retarded were traditionally divided by IQ scores into educable, trainable, and custodial; today, the more commonly used terms include mild, moderate, severe, or profound categories, based on the level of functioning and IQ.
Mild retardation This classification is used to specify an individual whose IQ test scores lie between 55 and 68 or 69, and it corresponds to an educators’ label of “educable retarded.” The individual is capable of learning basic academic subjects. Many people with mild retardation are able to live and work independently.
Moderate retardation Children who are moderately retarded have an IQ test score between 40 and 55; the term corresponds to the earlier label of “trainable retarded.” These children can usually
learn basic school and job skills and often achieve coached job goals and live with limited assistance.
Severe and profound mental retardation This classification applies to children with IQ scores below 25. These children are the most seriously impaired of the mentally retarded, often characterized by physical and sensory impairment as well as mental retardation. They can sometimes achieve supported job goals, but more typically they function in sheltered employment. They generally require significant assistance with daily living skills.
Treatment
Many public and private agencies that specialize in developmental disabilities can help children with mental retardation. Although there is no cure for this condition, retarded children can be taught and supported so that they can live rewarding, happy lives.
Every state is required by law to offer early intervention programs beginning at birth for children with mental retardation, and public schools must offer special education beginning at age three.
Prevention
It is possible to prevent some forms of mental retardation. During the past 30 years, significant advances in research have prevented many cases of mental retardation. For example, every year in the United States, about 250 cases of mental retardation due to PKU are prevented by newborn screening and dietary treatment. Newborn screening and thyroid hormone replacement therapy prevent 1,000 cases of mental retardation due to congenital hypothyroidism, and more than 1,000 cases of mental retardation from Rh disease and severe jaundice are prevented by using anti-Rh immune globulin to prevent Rh disease. The HIB vaccine prevents another 5,000 cases of mental retardation caused by HIB diseases, and 4,000 cases of mental retardation due to measles encephalitis can be prevented because of the measles vaccine. Countless numbers of cases of mental retardation caused by rubella during pregnancy are prevented thanks to the rubella vaccine.
Removing lead from the environment reduces brain damage in children, and child safety seats and bicycle helmets reduce head trauma. Early intervention programs with high-risk infants and children have shown remarkable results in reducing the predicted incidence of subnormal intellectual functioning.
Finally, early prenatal care and preventive measures before and during pregnancy increase a woman’s chances of preventing mental retardation. Pediatric AIDS is being reduced by AZT treatment of the mother during pregnancy, and dietary supplementation with folic acid reduces the risk of neural tube defects. Research continues on new ways to prevent mental retardation, including research on the development and function of the nervous system, a wide variety of fetal treatments, and gene therapy to correct the abnormality produced by defective genes.
Between 6.2 million and 7.5 million people have mental retardation, which is 10 times more common than CEREBRAL PALSY and 28 times more prevalent than neural tube defects such as SPINA BIFIDA. Mental retardation cuts across the lines of racial, ethnic, educational, social, and economic backgrounds, so that one out of 10 American families is directly affected by mental retardation.
The effects of mental retardation vary considerably among people, just as the range of abilities varies considerably among people who do not have mental retardation. About 87 percent will be mildly affected and will be only a little slower than average in learning new information and skills. As children, their mental retardation is not easy to see and may not be identified until school age. The remaining 13 percent of people with mental retardation (those with IQs under 50) will have serious limits in function. However, with early intervention, a good education, and appropriate supports as an adult, all can lead satisfying lives in the community.
People with mental retardation may have trouble communicating, interacting with others, and being independent. There may also be concerns with regard to understanding health and safety issues. Not all skills are necessarily impaired, and children with mental retardation may learn to function independently in many areas. However, education programs, providing skilled assistance and ongoing support, are necessary for determining appropriate living and work environments.
Symptoms
Most parents tend to notice a problem within the first year or two of life. While all children develop different skills at different times, significant lags in several areas of development are an early warning sign. Children with mental retardation tend to reach developmental milestones later than youngsters of normal intelligence. They may not learn to sit, crawl, or walk until well after their second birthdays. Speech is likewise delayed, and some severely retarded children never learn to talk at all.
Cause
Mental retardation can be caused by any condition that impairs development of the brain before birth, during birth, or in the childhood years. Several hundred causes have been discovered, but about a third of the time the reason remains unknown. The three most common known causes of mental retardation are DOWN SYNDROME, FETAL ALCOHOL SYNDROME, and FRAGILE X SYNDROME.
Genetic conditions These conditions are caused by abnormal genes or from other disorders of the genes caused during pregnancy by infections, overexposure to X rays, and other factors. More than 500 genetic diseases are associated with mental retardation, such as:
• PKU (PHENYLKETONURIA) A single gene disorder caused by a defective enzyme
• Down syndrome A chromosomal disorder that happens sporadically, caused by too many chromosomes, or by a change in structure of a chromosome
• Fragile X syndrome A single gene disorder located on the X chromosome that is the leading inherited cause of mental retardation
Prenatal problems Using alcohol, drugs, or smoking during pregnancy can cause mental retardation. Other risks include malnutrition, certain environmental contaminants, and illnesses of the mother during pregnancy, such as TOXOPLASMOSIS, CYTOMEGALOVIRUS, GERMAN MEASLES, and SYPHILIS. Pregnant women who are infected with HIV and HERPES may pass the virus to their child, leading to future neurological damage.
Problems at birth Although any unusual stress during birth may injure the infant’s brain, prematurity and low birth weight are more likely to predict serious problems than any other conditions.
Problems after birth Childhood diseases such as WHOOPING COUGH, CHICKEN POX, MEASLES, and HIB disease (which may lead to MENINGITIS and ENCEPHALITIS) can damage the brain, as can accidents such as a blow to the head or near drowning. Lead, mercury, and other environmental toxins can cause irreparable damage to the brain and nervous system.
Socioeconomic Children in poor families may become mentally retarded because of malnutrition, disease-producing conditions, inadequate medical care, and environmental health hazards. Also, children in disadvantaged areas may be deprived of many common cultural and day-to-day experiences provided to other youngsters. Research suggests that such under-stimulation can result in irreversible damage and can serve as a cause of mental retardation.
Diagnosis
Mental retardation is diagnosed primarily on the basis of intelligence testing, but affected children often demonstrate other brain problems such as attention deficits, movement problems, and perceptual difficulties. Dexterity and coordination also may be limited. If the child’s doctor suspects a problem, parents may be referred to a psychologist or other mental health expert, who can administer a number of special tests, including standardized intelligence tests and a standardized adaptive skills test. Next, an expert should describe the child’s strengths and weaknesses in intellectual and adaptive behavior skills, emotions, physical health, and environment. These skills can be assessed by formal testing, observations, interviews, and interacting with the child in daily life.
Intelligence testing alone is only one measure of functioning ability, however. A child with limits in intellectual functioning who does not have limits in adaptive skill areas may not be diagnosed as having mental retardation. “Adaptive skill areas” are those daily living skills needed to live, work, and play in the community and include communication, self-care, home living, social skills, leisure, health and safety, self-direction, functional academics (reading, writing, basic math), community use, and work. Adaptive skills are assessed in the child’s typical environment.
Careful assessment is important because many children have been misdiagnosed with mental retardation, particularly at a young age, and are later diagnosed with profound learning disabilities but with average or above average intelligence.
Types of Mental Retardation
Individuals with mental retardation are not a homogenous group but have widely differing levels of functioning. While the term mental retardation still exists as a clinical diagnosis, experts today prefer terms such as developmental disability, which some believe does not carry the same negative connotations. In the past, those who were retarded were traditionally divided by IQ scores into educable, trainable, and custodial; today, the more commonly used terms include mild, moderate, severe, or profound categories, based on the level of functioning and IQ.
Mild retardation This classification is used to specify an individual whose IQ test scores lie between 55 and 68 or 69, and it corresponds to an educators’ label of “educable retarded.” The individual is capable of learning basic academic subjects. Many people with mild retardation are able to live and work independently.
Moderate retardation Children who are moderately retarded have an IQ test score between 40 and 55; the term corresponds to the earlier label of “trainable retarded.” These children can usually
learn basic school and job skills and often achieve coached job goals and live with limited assistance.
Severe and profound mental retardation This classification applies to children with IQ scores below 25. These children are the most seriously impaired of the mentally retarded, often characterized by physical and sensory impairment as well as mental retardation. They can sometimes achieve supported job goals, but more typically they function in sheltered employment. They generally require significant assistance with daily living skills.
Treatment
Many public and private agencies that specialize in developmental disabilities can help children with mental retardation. Although there is no cure for this condition, retarded children can be taught and supported so that they can live rewarding, happy lives.
Every state is required by law to offer early intervention programs beginning at birth for children with mental retardation, and public schools must offer special education beginning at age three.
Prevention
It is possible to prevent some forms of mental retardation. During the past 30 years, significant advances in research have prevented many cases of mental retardation. For example, every year in the United States, about 250 cases of mental retardation due to PKU are prevented by newborn screening and dietary treatment. Newborn screening and thyroid hormone replacement therapy prevent 1,000 cases of mental retardation due to congenital hypothyroidism, and more than 1,000 cases of mental retardation from Rh disease and severe jaundice are prevented by using anti-Rh immune globulin to prevent Rh disease. The HIB vaccine prevents another 5,000 cases of mental retardation caused by HIB diseases, and 4,000 cases of mental retardation due to measles encephalitis can be prevented because of the measles vaccine. Countless numbers of cases of mental retardation caused by rubella during pregnancy are prevented thanks to the rubella vaccine.
Removing lead from the environment reduces brain damage in children, and child safety seats and bicycle helmets reduce head trauma. Early intervention programs with high-risk infants and children have shown remarkable results in reducing the predicted incidence of subnormal intellectual functioning.
Finally, early prenatal care and preventive measures before and during pregnancy increase a woman’s chances of preventing mental retardation. Pediatric AIDS is being reduced by AZT treatment of the mother during pregnancy, and dietary supplementation with folic acid reduces the risk of neural tube defects. Research continues on new ways to prevent mental retardation, including research on the development and function of the nervous system, a wide variety of fetal treatments, and gene therapy to correct the abnormality produced by defective genes.
Tags: adaptive skill areas, Below-average intellectual functioning abilities, intelligence quotient (IQ) testing, low adaptive functioning, MENTAL RETARDATION
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