The definition most often used in the United States is from the American Association on Mental Retardation
(AAMR). Mental retardation is defined as an IQ of approximately 70 or below, coexisting disadvantages or
impairments in adaptive functioning in two areas (communication, self-care, home-living,
social/interpersonal skills, the use of community resources, self-direction, functional academic skills, work,
leisure, health, and safety), and onset before age 18.
Mental retardation is diagnosed through the use of standardized tests of intelligence and adaptive behavior.
Mental retardation refers to certain limitations in mental functioning and in skills such as communicating,
daily self-care such as dressing or eating, and social skills. These limitations will cause a child to learn and
develop more slowly than a typical child. Mentally retarded children will often need extra help to manage the
challenges of school.
Mental retardation is not a disease. It's also not a type of mental illness, like depression. There is no cure for
mental retardation. However, most children with mental retardation can learn to do many things. It just takes
them more time and effort than other children. Every child with mental retardation is able to learn, develop,
and grow. With help, all children with mental retardation can live a satisfying life.
Signs of Mental Retardation in Children
There are many possible ways to recognize mental retardation. For example, children with mental retardation
• be developmentally delayed in sitting up, crawling, or walking, or talking, or have trouble speaking
• find it difficult to remember things
• not understand how to pay for things
• have trouble understanding social rules, knowing the consequences of their actions, solving problems,
and/or logical thinking
Types of Mental Retardation
A mentally retarded person is slow to learn and may be slow or limited in the development of physical skills.
Additional to physical skills other handicaps may be present, such as speech impairments, visual
impairments, hearing defects, or epilepsy. Because these secondary handicapping conditions are common
among individuals with mental retardation, this does not mean that persons with a speech impairment or
epilepsy are mentally retarded.
There are many degrees of mental retardation. Individuals who are severely retarded are able to learn only
the most basic self-care skills. Those who are mildly retarded are able to learn so much that, as adults, some
are no longer identified as being retarded. Three common classifications used include:
Mildly (Educable) - Mental Age 8-12; learn to approximately 6th grade level.
Moderately (Trainable) - Mental Age 5-8; cannot learn academic subjects in school.
Severely/Profoundly - Many require life-long care and supervision and are often confined to institutions.
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
• Birth Problems - for example premature birth, too rapid birth, prolonged birth, or any circumstance
that reduces the oxygen supply to the infant's E
• 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.
Testing and Diagnosis
The version for children (ages six through 16) is the Wechsler Intelligence Scale for Children-III (WISC-
III). These tests comprise a number of different verbal tests which measure areas such as vocabulary
knowledge, general knowledge about the world, verbal logical reasoning, social judgment and common
sense, arithmetic skills, short-term memory and attention. The Performance test measure nonverbal areas
including visual-motor coordination, perceptual organization, visual logical reasoning, and attention to detail.
The Full Scale IQ score is obtained from the scores of both the Verbal and Performance IQ scores.
The Vineland Adaptive Behavior Scales is a commonly used test to measure abilities in communication, daily
living, and motor skills. These domains are divided into sub-domains. Standard scores result from
comparing an individual’s ability to other people of similar age. This test is administered by interviewing a
family member or other person familiar with the individual’s functioning. The results are not valid if based
upon interviewing the individual.
To diagnose mental retardation, professionals look at the person's mental abilities (IQ) and his or her
adaptive skills. These are:
• A child's IQ or intellectual functioning, the innate ability of their brain to learn, think, solve problems,
and make sense of the world. Intellectual functioning (IQ) is usually measured by a test called an IQ test.
The average score is 100. People scoring below 70 to 75 are said to be mentally retarded.
• The child's adaptive behavior, whether they have the skills they need to live independently. Key skills
include daily living skills, communication skills, and social skills. To measure adaptive behavior,
professionals look at what a child can do in comparison to other children of his or her age.
Mental Retardation Treatment
A child with mental retardation can do well in school but is likely to need individualized help. The family will
work with preschool and school staff to develop an individualized plan, which will describe:
• The child's unique needs
• The services the school will provide to address those needs
• The unique responsibilities of the family
Many mentally retarded children need help with adaptive skills, which are daily living skills needed to
survive, work, and interact in the community. Teachers and parents can help a child work on these skills at
both school and home. Some of these skills include:
• Communicating with others
• Taking care of personal needs (dressing, bathing, going to the bathroom)
• Health and safety
• Home living (helping to set the table, cleaning the house, or cooking dinner)
• Social skills (manners, knowing the rules of conversation, getting along in a group, playing a game)
• Reading, writing, and basic math and
• As they get older, skills that will help them in the workplace
The vast majority (about 87%) of people with mental retardation will only be a little slower than average in
learning new information and skills. When they are children, their limitations may not be obvious. Their
mental retardation may not even be diagnosed until they get to school. As they reach adulthood, many people
with mild retardation can live independently. Other people may not even consider them as having mental
The remaining 13% of people with mental retardation score below 50 on IQ tests. These people will have
significant difficulty keeping up in school, at home, and in the community. They will need more intensive
support throughout their entire life.