Mental Retardation
...the child is 18 years old. Children with MR have low intelligence and have problems functioning in everyday life. They score very low on a test that measures mental ability. They learn more slowly than other children their same age. Children with MR often have other physical and emotional problems. They may have trouble hearing, seeing, or speaking. They may have problems communicating and socializing (having conversations, making wise judgments, etc.). They often have other disorders. Some children with MR feel depressed because they know they are not like other children their age. If the child can't talk, she may show her feelings by acting out or she may become withdrawn. (http://www.vh.org/Patients/IHB/Peds/CQQA/mentalretardation.html#4) Delayed development of skills such as walking and self care Late development of speech and language Poor coordination of movements, such as using the fingers to handle small objects Poor school performance Social and emotional immaturity (http://health.discovery.com/diseasesandcond/encyclopedia/2904.html) CAUSES/EFFECTS “Scientists can identify a specific cause in 60 to 70 percent of mental retardation cases. Causes include genetic conditions, disorders that occur as a fetus develops during pregnancy, and problems during or after birth. Some cases of mental retardation have multiple causes.”(http://encarta.msn.com/encnet/refpages/refarticle.aspx?refid=761552226) There are usually two types of causes; genetic and external causes. “Genetic causes include single-gene defects such as Fragile X syndrome and chromosomal disorders such as Down syndrome. Scientists in 1992 identified Fragile X syndrome as the most common inherited cause of mental retardation, responsible for up to 10 percent of cases. People with this condition inherit a defective gene that results in a weak spot on the X chromosome, a sex chromosome. The weak part of the chromosome is susceptible to breaking. Fragile X syndrome is more likely to cause retardation in males than females. Chromosomal disorders, which occur in about seven out of every 1000 infants, involve an abnormal number of chromosomes or changes in the structure of a chromosome. Down syndrome occurs when people inherit all or part of an extra copy of a pair of chromosomes known together as chromosome 21. Although regarded as genetic disorders, chromosomal disorders are not necessarily inherited. Both parents may have normal genes, with the defect resulting from a random error when chromosomes reproduce. Other genetic causes of mental retardation are inborn errors of metabolism. They involve inheritance of a defective gene unable to produce enzymes or proteins needed for critical cell functions. Scientists have identified more than 300 gene disorders involving inborn errors of metabolism. Many can result in mental retardation, including phenyllketonuria (PKU), Tay-Sachs disease, galactosemia, homocystinuria, maple syrup urine disease, and biotinidase deficiency.” (http://encarta.msn.com/encnet/refpages/refarticle.aspx?refid=761552226) Another common cause of mental retardation, congenital hypothyroidism, occurs in about one in every 4000 births. Infants with this disorder are unable to produce enough thyroxine, a hormone secreted by the thyroid gland. Mental retardation and stunted growth results unless they receive thyroid replacement therapy. The other type is external cause. A variety of problems during a woman’s pregnancy can cause mental retardation in her child. These problems include malnutrition; a mother’s use of alcohol or drugs; environmental toxins such as lead or mercury; viral infections, including rubella and cytomegalovirus; and untreated diseases such as diabetes mellitus. Fetal alcohol syndrome results from excessive consumption of alcohol during pregnancy and is the most common preventable cause of mental retardation in the United States. It occurs in one to three out of every 1000 births. Malnutrition during pregnancy is a common cause of mental retardation in developing countries, where many women do not consume adequate amounts of protein and other necessary nutrients. Some cases of mental retardation result from problems during birth, including premature birth, very low birth weight, and stresses to the fetus such as deprivation of oxygen. Infectious diseases during childhood, which are easily preventable through immunization, also can cause mental retardation when they result in complications. For example, measles, chicken pox, and whooping cough may lead to encephalitis and meningitis, which can damage the brain. Physical trauma to the brain can also cause mental retardation. Brain damage may result from accidental blows to the head, near drowning, severe child abuse, and childhood exposure to such toxins as lead and mercury. Experts believe that poverty and a lack of stimulation during infancy and early childhoods can be factors in mental retardation. Children raised in poor environments are more likely to experience malnutrition, lack of routine medical care, and environmental health hazards. “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 readily apparent and may not be identified until they enter school. As adults, many will be able to lead independent lives in the community and will no longer be viewed as having mental retardation. The remaining 13 percent of people with mental retardation, those with IQs less than 50, will have serious limitations in functioning. However, with early intervention, a functional education and appropriate supports as an adult, all can lead satisfying lives in the community.” (http://www.thearc.org/faqs/mrqa.html) PREVENTION Newborn screening programs can prevent some cases of mental retardation by identifying inherited conditions that may lead to retardation. All states in the U.S. require a blood test for congenital hypothyroidism and phenylketonuria (PKU). Infants with PKU cannot metabolize the amino acid phenylalanine, found in foods that contain protein. Once identified, these infants can be given a low-phenylalanine diet that prevents retardation. Some states require newborn screening for additional inherited diseases. Adult screening tests can identify carriers of other conditions before couples conceive a child. Individuals and couples with a family history of mental retardation can seek genetic counseling to evaluate their own risks and need for screening. Specialized laboratory tests, including amniocente...