Understanding Mental Retardation (MR)
Mental retardation (MR) is a generalized disorder, characterized by significantly impaired cognitive functioning and deficits in two or more adaptive behaviors with onset before the age of 18.
A wide variety of medical and environmental conditions can cause MR. Some are genetic; some are present before or at the time of conception; and others occur during pregnancy, during birth, or after birth. The common factor is that something interferes with the growth and development of the brain. Mental retardation affects about 1 - 3% of the population. However, doctors can identify a specific cause in only about one third of people with mild MR and in two thirds of people with moderate to profound MR
A family may suspect mental retardation if the child's motor skills, language skills, and self-help skills do not seem to be developing, or are developing at a far slower rate than the child's peers.
- Causes Of Mental Retardation
Not all the causes of mental retardation are known; however, more than 200 have been identified, and many others are suspected. The known causes can be placed into five categories:
Genetic Irregularities - for example x-ray exposure, incompatibility of genes inherited from parents, Rh blood factor incompatibility, error in metabolism, or recessive genetic traits. Examples of genetically caused mental retardation are Down syndrome, fragile X syndrome, and phenylketonuria (PKU).
Pregnancy Complications - for example poor nutrition, German measles, tumors, glandular disorders, infections, exposure to toxic agents, or radiation. Mental retardation can result when something goes wrong with the baby's development in the womb. There may be a problem with the way the baby's cells divide as it grows. Exposure to alcohol or rubella during pregnancy may also cause a baby to be born mentally retarded.
Birth Problems - for example premature birth, too rapid birth, prolonged birth, or any circumstance that reduces the oxygen supply to the infant
Early Childhood Problems - for example childhood diseases, especially in the very young (chicken pox, measles, meningitis, whooping cough); high fevers, severe injuries to the brain, lack of certain chemicals in the blood, or glandular imbalance. Mental retardation can also be caused by extreme malnutrition, inadequate medical care, or exposure to poisons such as lead or mercury.
Environmental Factors - for example being born and raised in a deprived environment where there is little opportunity to learn; or serious emotional problems.
Degrees of mental retardation
Not all people with mental retardation have the same level of intelligence. The scientific method of measuring intelligence is through standardized psychological tests called IQ tests. IQ or intelligence quotient is the percentage of intelligence a person has, in comparison to a normal person from a similar background. An IQ of 100 is considered normal intelligence. The lesser the IQ, the more severe is the level of mental retardation. Based on IQ, mental retardation can be classified into different degrees as follows:
| IQ | Degree of MR | |
|---|---|---|
| 90 - 110 | Normal | |
| 85 - 90 | Dull Normal | |
| 70 – 85 | Borderline | |
| 50 – 70 | Mild mental retardation | Group constitutes by far the largest number of those labeled mentally retarded. Persons in this group are considered "educable", and their intellectual levels, as adults are comparable to that of the average 8 to 11 year old child. Ordinarily they do not show the signs of brain pathology or other physical anomalies. They require some measure of supervision due to limited ability to foresee the consequences of their actions. With early diagnosis, parental assistance, and special educational programs, the great majority can adjust socially, master simple academic and occupational skills, and become self-supporting citizens. |
| 35 – 50 | Moderate | Individuals in this group are likely to fall in the educational category of "trainable". In adult life, individuals classified as moderately retarded attain intellectual levels similar to that of the average 4 to 7-year-old child.
While some of the brighter ones can be taught to read and write a little, and some manage to achieve a fair command of spoken language, the rate of learning is relatively slow among members of this group, and the level of conceptualizing extremely limited. Physically, they usually appear clumsy and ungainly, and they suffer from bodily deformities and poor motor coordination. A distinct minority of these children is hostile and aggressive, but typically they present an affable and somewhat vacuous personality picture. With early diagnosis, parental help, and adequate opportunities for training, most of the moderately retarded can achieve independence in daily self-care, acceptable behavior, and economic usefulness in a family or other sheltered environment. Whether or not they require institutionalization usually depends on their general level of adaptive behavior and the nature of their home situation. |
| 20 – 35 | Severe | Among these individuals, motor and speech development is severely retarded and sensory defects and motor handicaps are common. These children with mental retardation can develop limited levels of personal hygiene and self-help skills, which somewhat lessen their dependence, but all their lives they will be dependent on others for care. However, many profit to some extent from training and can perform simple occupational tasks under supervision. |
| Below 20 | Profound | The term "life support" mental retardate is sometimes used in referring to individuals in this category. Most of these persons are severely deficient in adaptive behavior and unable to master any but the simplest tasks. Useful speech, if it develops at all, is on the rudimentary level. Severe physical deformities, central nervous system pathology, and retarded growth are typical, and convulsive seizures, mutism, deafness, and other physical anomalies are common. These people should ideally be kept in custodial care all their lives. However, health and resistance to disease is lowered, and a short life expectancy is usual. |
