Mental retardation is below average mental ability usually present from birth or
early childhood. Those who suffer from mental retardation usually have lower mental
development than normal people, and learning difficulties along with problems
About 4% of the total population suffered from mental retardedation.
A persons intelligence level is determined by their heredity and the
environment in which they live. In many cases the cause is a mystery.
But, conditions during pregnancy can cause or contribute to mental retardation in
the newborn child. Conditions that contribute may include lack of proper
nutrition, the use of certain medications, radiation treatment, alcohol
abuse, and some viral infections. Diseases such as Down's Syndrome, can
be a cause of mental retardation. A number of
genetic disorders may also cause mental retardation. Some, such as low thyroid levels, can be
properly treated before
mental retardation happens. Premature birth difficulties,
injuries to the head during the birth process, and extremely low oxygen levels during
the birth process may also cause
Diagnosis and Prognosis
Once mental retardation has occurred, it is usually irreversible.
Diagnosing mental retardation early makes remedial education and long-term
Subaverage intelligence can be identified and measured by standardized
intelligence tests. Such tests have a middle-class bias but are reasonably
accurate predictors of intellectual performance, particularly in an older child.
Children with and IQ of 69 to 84 have difficulty in school learning but are
not mentally retarded. They are rarely identified before beginning school,
when educational and sometimes behavioral problems become evident. With
special educational help, they can usually succeed in school and lead normal
All children with mental retardation can benefit from education.
Children with mild retardation may attain fourth to sixth grade reading skills.
Although they have difficulty reading, most mildly retarded children can learn
the basic educational skills needed for everyday life. They require some
supervision and support and special educational and training facilities.
They may later require a sheltered living and work situation. Though
usually free or obvious physical defects, people who are mildly retarded may
The mildly retarded are often immature and unsophisticated, with a poorly
developed capacity for social interaction. Their thinking is concrete and
they are often unable to generalize. They have difficulty adjusting to new
situations and may demonstrate poor judgment, lack of foresight, and
gullibility. Although they don't commonly commit serious offenses, the
mildly retarded may commit impulsive crimes, often as members of a group and
sometimes to achieve peer group status.
Children with moderate retardation are obviously slow in learning to speak
and reaching other developmental milestones, such as sitting up and speaking.
Given adequate training and support, mildly and moderately retarded adults can
live with varying degrees of independence within the community. Some can
cope with just a little support in a halfway house, whereas others need greater
The severely retarded child is trainable to a lesser degree than a child who
is moderately retarded. The profoundly retarded child usually can't learn
to walk, talk or understand very much.
The life expectancy of children with mental retardation may be shortened,
depending on the cause and severity. In general, the more severe the
retardation, the shorter the life expectancy.
Genetic counseling gives parents of a child with retardation knowledge and
understanding of the cause of retardation. Counseling helps them assess
the risk of having another child who is retarded. Amniocentesis and
chorionic villus sampling are diagnostic tests that can detect a number of
abnormalities, including genetic abnormalities and spinal cord or brain defects
in the fetus. Amniocentesis or chorionic villus sampling is advisable for
all pregnant women over 35 years old because of their increased risk of having a
baby with Down's Syndrome. Ultrasound examination may also identify fetal
brain defects. The serum alpha-fetoprotein level in the mother's blood can
be measured to screen for Down's Syndrome and Spina Bifida. The rubella
vaccine has dramatically decreased German measles as a cause of mental
The primary care doctor, in consultation with a number of specialists,
develops a comprehensive, individualized program for the child with retardation.
A child with developmental delays should be started in an early intervention
program as soon as the diagnosis of mental retardation is suspected.
Emotional support of the family is an integral part of the program. A
child with retardation usually does best living at home or at a community-based
residence and, if possible, attending a normal day care center or preschool
The level of social competence is as important as the IQ in determining how
limiting the retardation will be. The IQ and social competence are both
problems for children at the lower end of the IQ scale. For children with
higher IQ scores, other factors, such as physical handicaps, personality
problem, mental illness, and social skills, can determine how much care is
Source: Margolis, Simeon, The Johns Hopkins Medical Handbook, 2001