There are several hundred possible causes of mental retardation. They include genetic conditions (e.g., Down syndrome, fragile X syndrome); prenatal problems (e.g., fetal alcohol syndrome, rubella, malnutrition); problems apparent at birth (e.g., low birth weight and prematurity); and problems that occur after birth (e.g., injuries and childhood diseases like measles that can lead to meningitis and encephalitis). The most commonly identified causes of mental retardation are Down syndrome, fragile X syndrome, and fetal alcohol syndrome. In many cases the cause is never known.
Most mentally retarded children are capable of learning new things, both in and out of a formal school setting, but they may learn at a slower pace than other children. Schools are responsible for providing an appropriate education for retarded children. Many teachers and parents feel that the practice of mainstreaming, or inclusion, which places such children in standard classrooms for at least part of the day, helps them to feel more a part of society and helps others to better understand their special needs and capabilities.
Many cases of mental retardation are now prevented by improved health care. Vaccines against rubella and measles prevent an estimated 3,000 cases of mental retardation in the United States yearly. Vaccination against Haemophilus influenzae b (Hib), a cause of childhood meningitis, is expected to prevent 3,000 more. Prevention of Rh disease (see Rh factor), screening and treatment for phenylketonuria, and emphasis on prenatal care and the dangers of poor nutrition or alcohol consumption during pregnancy have also resulted in a decrease in cases of mental retardation in the United States. Mental retardation rates in poor nations, however, are rising.
The treatment of mentally retarded people has always reflected the changes in society. They have been officially referred to as idiots and as the feebleminded. The introduction of the IQ test was followed by a classification system that used such terms as moron (IQ of 51-70), imbecile (26-50), and idiot (0-25); later these terms were softened and classifications redefined somewhat to mild (IQ of 55-70), moderate (40-54), severe (25-39), and profound (0-24) retardation. The term mentally retarded itself, although still commonly used, has been replaced in some settings by the term developmentally disabled.
Mentally retarded people have been subjected to unnecessary institutionalization and, as a result of the eugenics movement, involuntary sterilization. The deinstitutionalization movement of the 1970s reflected a concern for the civil rights of mentally retarded. Very few of the mentally retarded are now institutionalized; most now live independently, with their families, or in group homes. The emphasis on education and self-sufficiency seen in the late 20th cent. mirrors a similar movement in the 1840s.
See M. Adams, Mental Retardation and Its Social Dimensions (1971); A. Clarke et al., ed., Mental Retardation: The Changing Outlook (1985); E. Zigler, Understanding Mental Retardation (1986); American Association on Mental Retardation, Mental Retardation: Definition, Classification, and Systems of Support (1992).
See G. N. Grob, Mental Illness and American Society, 1875-1940 (1983); P. Brown, ed., Mental Health Care and Social Policy (1985); T. Richardson, The Century of the Child (1989); E. F. Torrey, Nowhere to Go (1992).
Subaverage intellectual ability that is present from birth or infancy and is manifested by abnormal development, learning difficulties, and problems in social adjustment. A standardized intelligence test is a common method of identification. Individuals with IQ scores of 53–70 are usually classified as having mild intellectual disability and are able to learn academic and prevocational skills with some special education. Those with scores of 36–52 are classified as having moderate intellectual disability and are able to learn functional academic skills and undertake semiskilled work under supervised conditions. Those in the severe (21–35) and profound (below 21) ranges require progressively more supervision or full-time custodial care. Intellectual disability can be caused by genetic disorders (such as Down syndrome), infectious diseases (such as meningitis), metabolic disorders, poisoning from lead, radiation, or other toxic agents, injuries to the head, and malnutrition.
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Any illness with a psychological origin, manifested either in symptoms of emotional distress or in abnormal behaviour. Most mental disorders can be broadly classified as either psychoses or neuroses (see neurosis; psychosis). Psychoses (e.g., schizophrenia and bipolar disorder) are major mental illnesses characterized by severe symptoms such as delusions, hallucinations, and an inability to evaluate reality in an objective manner. Neuroses are less severe and more treatable illnesses, including depression, anxiety, and paranoia as well as obsessive-compulsive disorders and post-traumatic stress disorders. Some mental disorders, such as Alzheimer disease, are clearly caused by organic disease of the brain, but the causes of most others are either unknown or not yet verified. Schizophrenia appears to be partly caused by inherited genetic factors. Some mood disorders, such as mania and depression, may be caused by imbalances of certain neurotransmitters in the brain; they are treatable by drugs that act to correct these imbalances (see psychopharmacology). Neuroses often appear to be caused by psychological factors such as emotional deprivation, frustration, or abuse during childhood, and they may be treated through psychotherapy. Certain neuroses, particularly the anxiety disorders known as phobias, may represent maladaptive responses built up into the human equivalent of conditioned reflexes.
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Science of maintaining mental health and preventing disorders to help people function at their full mental potential. It includes all measures taken to promote and preserve mental health: rehabilitation of the mentally disturbed, prevention of mental illness, and aid in coping in a stressful world. Community mental health acknowledges the relation between mental health, population pressures, and social unrest. It also deals with social problems, from drug addiction to suicide prevention. Treatment of the mentally ill through the ages has ranged from neglect, ill treatment, and isolation to active treatment and integration into the community, often in response to crusading reformers. Prevention of mental illness includes prenatal care, child-abuse awareness programs, and counseling for crime victims. Treatment includes psychotherapy, drug therapy, and support groups. One of the most important efforts is public education to combat the stigma still attached to mental illness and encourage those affected to seek treatment.
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In criminal law, a disease, defect, or condition of the mind that renders one unable to understand the nature of a criminal act or the fact that it is wrong. Tests of insanity are not intended as medical diagnoses but rather only as determinations of whether a person may be held criminally responsible for his or her actions. The most enduring definition of insanity in Anglo-American law was that proposed by Alexander Cockburn (1843). Many U.S. states and several courts have adopted a standard under which the accused must lack “substantial capacity either to appreciate the criminality of his conduct or to conform his conduct to the requirements of the law.” Some states have abolished the insanity plea, and others allow a finding of “guilty but mentally ill.” Seealso diminished responsibility.
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