A mental disability can reveal its presence in many different ways. The functioning of the brain is usually less refined, and the progress of a mentally disabled child develops at a slower rate compared to the average child.
Someone with a mental disability tends not to think as quickly as other people. His or her mental processes are usually less sophisticated and less agile, and the child takes longer to reach the same intellectual stage as do others of the same age. But such children can feel anger, frustration, happiness and other emotions as deeply as anyone else, and obtains just as much satisfaction from achieving their individual potential. About one baby in 250 is born with a severe mental disability. Many more are slightly affected. If a baby has no concomitant physical abnormalities, such as the facial and other features of Down’s syndrome, it may be many months before either parents or doctors realize the child is mentally retarded. It may also have problems such as a hearing or visual disorder, cerebral palsy, convulsions or a speech disorder which again are difficult to detect in a young baby. A child who is mentally retarded is not necessarily disabled by his slowness. There are degrees of mental retardation and there are many causes, some of which have a relatively minor effect. A child whose mental ability has not reached its full potential for whatever reason may be retarded compared with what he might have been capable of, yet he may be able to manage well in life and attend an ordinary school. However, most children in whom mental retardation is apparent are disabled. They may need extra care all their lives and usually cannot be taught in ordinary schools.
Educational subnormality is a term used to describe a child who is intellectually unable to manage optimally at an ordinary school. Some children are obviously destined for special schooling from babyhood on- wards but others are difficult to categorize. Careful and continual assessment and observation are necessary in order to reach a decision that will be in the child’s best educational interests. Generally schools for the mentally disabled fall into two categories: those for the mildly educationally subnormal (ESN) and those for the severely subnormal (ESN/S). Today, teachers, psychologists and doctors are only too well aware that it is difficult to assess a young pre-school child. If at any time it is thought that the wrong decision has been made, the system should allow for the mistake to be put right as soon as possible for everyone’s sake. As a child grows older, his lack of mental agility becomes apparent and the gap widens between him and other children of his own age. Intelligence testing and developmental assessment can give some idea of the child’s mental or developmental ‘age’ in each area of ability. There comes a time for each area when the child will probably make little further progress, if at all, but it is impossible to predict when this will be. Such tests by themselves are by no means infallible; the younger a child, the poorer a predictor of his potential intelligence they are. Provided their limitations are understood, they have some use. The intelligence quotient (IQ) ranges sometimes used to determine which children should go to which schools should ideally be interpreted loosely. Two children of identical intelligence as measured by an IQ test may turn out to have very different abilities and potential in everyday-life.
While broad indications can be given about how a young mentally-disabled child will develop, each child is an individual and so his outlook is unique. His personality, the personalities of his parents, siblings, teachers and others he comes into contact with, his environment and what it can offer, and the various opportunities he meets all help to determine whether or not he fulfils his potential. Academic intelligence is of minor importance compared with a child’s ability to enjoy life and to make others happy around him.
Improving educational potential
From time to time there are reports of remarkable achievements in raising IQ scores of mentally disabled children. Unfortunately, these cases are the exception rather than the rule and generally the evidence gives little hope for any schemes for the dramatic improvement of the mentally disabled. This does not mean, however, that they cannot be helped. The amount of improvement possible for a mentally disabled child depends upon the limitations imposed by the severity of his or her handicap. Some children can be taught basic self-care and in certain cases vocational skills to enable them to integrate into society. With very severely disabled children, a response such as a cry or gesture may be considered a great achievement. In order to provoke such responses, some researchers have found that stimulation with background music has produced encouraging results.
Causes and prevention of disabilities
For a large proportion of mentally disabled children, no cause is ever found. The known causes can be grouped according to when they act. The first group includes those present before the baby is born. Genetic abnormalities are carried by the genes in the ovum or sperm of a parent: Down’s syndrome (mongolism) and phenylketonuria (PKU) are examples. If a pregnant mother has an infection, her baby may also suffer, and mental disability is one of the problems that may result from German measles (rubella), toxoplasmosis and cytomegalovirus infection. Severe malnourishment during pregnancy can harm the unborn baby’s developing brain and cause retardation. Problems with placental function can be hazardous to a baby’s mental development, as can a lack of maternal thyroid, and the effects of certain drugs taken by the mother during pregnancy. Causes of mental disability acting around the time of birth include a lack of oxygen reaching a baby during or immediately after birth, head injury during labour, and severe .
In the infant, brain damage leading to mental disability can arise from meningitis, encephalitis, head injuries, low levels of thyroid hormones, and poisoning.
A lack of stimulation can cause temporary mental retardation in a child. In order that a child can achieve his full potential at any age, he needs to be given the opportunity to learn from being talked to, listened to, encouraged and played with by someone who is sensitively responsive.
It is impossible to prevent mental disability in a large number of children at present, partly because doctors frequently do not know the basic causes. A few conditions are genuinely preventable: examples include phenylketonuria (accumulation in the body of the amino acid phenylalanine caused by the lack of the enzyme that normally breaks it down) and cretinism (caused by a deficiency of thyroid hormones in the child). Mental disability resulting from infection, whether before or after birth, is preventable if diagnosed early enough and if there is an effective treatment. A pregnant woman should keep clear of anyone with an infection unless this is known to be harmless to her and her unborn baby. In countries with an adequate food supply, malnourishment, caused for instance by excess vomiting during pregnancy, is preventable. Placental problems can nowadays be diagnosed early in most cases and if necessary the pregnancy can be ended prematurely by inducing labour artificially or delivering the baby by Caesarian section. Theoretically, mental disability arising from birth problems is mostly avoidable with good obstetric care.
In practice, even the best obstetric units have a few unavoidable disasters. The prevention of mental disability by selective abortion of foetuses known to be suffering from a genetic disorder such as Down’s syndrome is controversial; it is available in some centres but is unacceptable to many women. Special tests such as the examination ofin the amniotic fluid (amniocentesis) are necessary for the diagnosis to be made. Today such assessment has been made easier to perform: a small tissue sample from the villi, the tiny finger-like projections of the chorion connecting with the placenta, is taken from the womb by way of the vagina. This test, called chorionic villus sampling, can be performed very early (at about the eighth week) in contrast to an amniocentesis (performed about the sixteenth week of pregnancy).
Treatment and care
In most cases mental disability is irreversible but that is not to say that no treatment is possible. The point of treating a disabled child is to maximize his potential ability. Before embarking on any course of treatment it helps to know what the child can do in each sphere of development.
Developmental testing provides a crude yardstick for measuring the rate of progress, and each child should be assessed regularly by a team of specialists who will advise on the best plan of management and treatment. Mentally retarded children are like any others in their infinite range of personalities. There are some specific problems when it comes to their care. Some of them are also physically disabled, with the additional problems or care that can bring. Parents have to be even more on their guard against potentially dangerous situations when looking after a mentally handi-
Although mongoloid children are physically and mentally behind in development, they are usually cheerful, affectionate and active. Because their outward appearance is clearly different, they are easily recognized by everyone and sudden, unexpected situations do not often occur. The degree of mental disability varies; some learn to speak quite well and nearly all learn to walk.