Intellectual Functioning 
Mental retardation is when your below average level of intellectual functioning, usually defined by an IQ of below 70 to 75, combined with limitations in the skills necessary for daily living. Daily living skills include such things as communication, the ability to care for oneself, and the ability to work. The definition of mental retardation has evolved over the years.
Categorizations Of Mental Retardation Prior categorizations of mental retardation, defined solely by IQ, have largely been abandoned in favor of an approach that looks at how much support the retarded person needs in various areas of his or her life at any given time. Such support can range from intermittent help in such things as finding housing or a job, to pervasive, daily, lifelong help in all areas.
Retardation Causes Mental retardation causes are plenty. 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 prematurely.
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.
Treatment Of Mentally Retarded People 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).
Developmentally Disabled 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.
Mental Retardation Is Preventable 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.
Vaccination 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.
Eugenics Movement
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.
MR Diagnosis There are many behavioral traits associated with MR but are not deemed criteria for an MR diagnosis. These traits include: aggression, dependency, impulsivity, passivity, self-injury, stubbornness, low self-esteem and low frustration tolerance (Morrison, 1995). Some may have
mood disorders such as psychotic disorders or attention difficulties though others are pleasant, otherwise healthy individuals (Morrison, 1995).
Physical Traits Physical traits may also set those with MR apart though at the same time, there are individuals with MR who have normal appearances. More overt traits are shortness in size, malformations of facial elements (eyes, ears), seizures and hemangioma.
Individual Standard Assessment Mental Retardation refers to below-average general intellectual functioning with associated deficits in adaptive behavior that occurs before age 18. Usually onset is in infancy or before birth and when onset is at age 18 or after, it is referred to as dementia; this can co-exist with an MR diagnosis (Morrison, 1995). Intelligence level as determined by individual standard assessment is less than 70 and ability to adapt to demands of normal life are impaired.
Adaptation In Individuals This distinction is important from individuals with low IQ scores who are able to adapt to demands of everyday life (Morrison, 1995). Adaptation in individuals with MR is helped by interventions in the form of education, job training, support from family as well as individual characteristics such as motivation and personality.
Causes Of Mental Retardation Retardation is determined in only 25% of the cases. Failure to adapt normally and grow intellectually may become apparent early in life or, in the case of mild retardation, not become recognizable until school age or later. The failure to achieve developmental milestones is suggestive of mental retardation. Causes of mental retardation can be roughly broken down into several categories:
Unexplained Causes Genetic abnormalities and inherited metabolic disorders (chromosomal abnormalities,
Tay-Sachs, tuberous sclerosis) (about 5%)
Early pregnancy factors (Down’s syndrome, maternal substance use, infections) (about
30%)
Later pregnancy and perinatal factors (prematurity, anoxia, birth trauma, fetal
malnutrition) (about 10%)
Acquired childhood physical conditions (lead poisoning, infections, trauma) (about
5%)
Environmental influences and mental disorders (cultural deprivation, early-onset
Schizophrenia) (about 20%)
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