MENTAL RETARDATION AND DEVELOPMENTAL DISORDERS

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MENTAL RETARDATION AND DEVELOPMENTAL DISORDERS >>

Abnormal Psychology PSY404

Lesson 42

MENTAL RETARDATION AND DEVELOPMENTAL DISORDERS

Mental Retardation

Example: A is a teenage boy who has shown problems in intellectual and social functioning; he needs

help to eat, to bath and to dress up.

What is mental retardation?

Why study mental retardation?

All people with mental retardation have impaired intellectual abilities, but they vary widely in

academic ability, social functioning, and life skills.

Some people with profound retardation require total care and live their entire lives in institutions.

However, most people with mental retardation learn self-care and vocational skills that allow them

to live in the community.

Many people with mental retardation suffer from emotional difficulties, a fact that is overlooked all

too often.

What is Mental Retardation?

Mental retardation is

1- Significant limitations in intellectual functioning

2- Significant limitations in adaptive functioning

3- Onset before age 18 years.

The American Association on Mental Retardation (AAMR), the leading organization for

professionals concerned with mental retardation, defines mental retardation somewhat differently

than DSM-IV-TR. However, both definitions generally agree on the three major criteria for mental

retardation, mentioned above.

The AAMR and DSM-IV-TR both define subaverage intellectual functioning in terms of a score on

an individualized intelligence test, a standardized measure for assessing intellectual ability.

Intelligence tests yield a score called the intelligence quotient, or IQ, the test's rating of an

individual's intellectual ability.

Symptoms of Mental Retardation

Defining intelligence can be controversial, and definitions and measures of intellectual ability have

changed over the years. Early versions of intelligence tests derived an IQ by dividing the individual's

"mental age" by his or her chronological age. Mental age was determined by comparing an individual's

test results with the average obtained for various age groups. Contemporary intelligence tests have

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abandoned the concept of mental age and instead have adopted the concept of the "deviation IQ".

According to this theory of "deviation IQ", intellectual ability follows the normal distribution in the

population, a bell-shaped frequency distribution.

The individual's IQ is determined based on how the person scores on an intelligence test relative to the

norms for his or her age group. IQ tests are widely used, and they have demonstrated value for

predicting performance in school. Moreover, IQ is a trait that is stable over time.

Despite the value of IQ tests in predicting academic performance, a number of important questions

have been raised about them. One of the most controversial questions is whether intelligence tests are

"culture-fair." Culture-fair tests contain material that is equally familiar to people who differ in their

ethnicity, native language, or immigrant status. Tests that are culturally biased contain language, examples,

or other assumptions that favor one ethnic group, particularly members of the majority group, over

another.

Another controversy is how well intelligence is measured among people with mental retardation. Many

people with mental retardation have sensory or physical disabilities that impede their performance on

standard IQ tests; thus they must take tests that are not influenced by their particular disability. Despite

the difficulties, evidence indicates that, if anything, the IQ test scores of people with mental retardation

are more reliable and valid than IQ scores in the normal range. Common sense, social sensitivity, and

"street smarts" are also part of what most of us would consider intelligence, and they are not measured

by IQ tests.

Both the AAMR and DSM recognize that intelligence is more than an IQ score; thus they include

adaptive behavior as a part of their definitions of mental retardation. The most basic concern about

intelligence tests is the most important one: What is intelligence? Intelligence tests measure precisely

what their original developer, Alfred Binet, intended them to measure: potential for school

achievement. IQ tests predict school achievement fairly well. However, school achievement is not the

same as "intelligence."

The AAMR suggests that adaptive behavior includes conceptual, social, and practical skills.

· Conceptual skills focus largely on community self-sufficiency, and incorporate communication,

functional academics, self-direction, and health and safety from DSM-IV-TR.

· Social skills focus on understanding how to conduct oneself in social situations and include social

skills and leisure from the DSM-IV-TR list.

· Practical skills focus on the tasks of daily living and include self-care, home living, community use,

health and safety, and work from the DSM-IV-TR.

Adaptive skills are difficult to quantify. As with the definition of IQ, the AAMR now defines a

significant limitation in adaptive behavior as a score that is two standard deviations below the mean on

a standardized measure of adaptive behavior in conceptual, social, or practical skills.

An argument has been made for defining retardation solely on the basis of intelligence testing, because

current measures of adaptive skills are imprecise. However, the adaptive skills criterion highlights the

importance of assessing life functioning in borderline cases, as well as the need for services among

people with mental retardation.

The third criterion for defining mental retardation is onset before 18 years of age. This criterion

excludes people whose deficits in intellect and adaptive skills begin later in life as a result of brain injury

or disease. People with mental retardation have not lost skills they once had mastered, nor have they

experienced a notable change in their condition.

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Diagnosis of Mental Retardation

· In 1866, the British physician Langdon Down first described a subgroup of children with mental

retardation who had a characteristic appearance.

· Down's classification helped subsequent scientists to establish a specific etiology for what we now

know as Down syndrome.

· The creation of IQ tests in the early twentieth century also greatly furthered the classification of

mental retardation.

· Once academic potential could be measured, controversy grew about what IQ score cutoff should

define mental retardation.

· The AAMR has set the cutoff at two standard deviations below the mean (70).

· Today, mental retardation can be classified according to two different criteria.

· One criterion is based on IQ scores; the other is according to known or presumed etiology.

· The AAMR uses a multiaxial diagnosis of mental retardation in which health, including etiological

factors, is rated on a separate axis.

· A more controversial aspect of the AAMR sub-classification is the ratings of four levels of

"intensity of needed support" across nine different areas of functioning.

· Today, mental retardation can be classified according to two different criteria.

· One criterion is based on IQ scores; the other is according to known or presumed etiology.

The goal in rating support intensities is to acknowledge the diversity of skills and needs among people with

mental retardation both as people and for treatment planning.

In adopting the support intensities approach, AAMR abandoned a long tradition still followed in the DSM-

IV-TR of dividing mental retardation into four levels primarily based on IQ scores: mild, moderate, severe,

and profound.

Levels of Mental Retardation

1- Mild mental retardation is the designation for those with IQ scores between 5055 and 70. People

with mild mental retardation typically have few, if any, physical impairments, generally reach the sixth-

grade level in academic functioning, acquire vocational skills, and typically live in the community with

or without special supports.

2- People with moderate mental retardation have IQs between 3540 and 5055. They may have

obvious physical abnormalities such as the features of Down syndrome. Academic achievement

generally reaches second-grade level, work activities require close training and supervision, and special

supervision in families or group homes is needed for living in the community.

3- Severe mental retardation is defined by IQ scores between 2025 and 3540. At this severity level,

motor development typically is abnormal, communicative speech is sharply limited, and close

supervision is needed for community living.

4- Profound mental retardation is characterized by an IQ below 2025. Motor skills, communication,

and self-care are severely limited, and constant supervision is required in the community or in

institutions.

A diagnosis of mental retardation literally might mean a difference between life and death.

The United States Supreme Court recently ruled that the death penalty is "cruel and unusual

punishment" for someone with mental retardation, and therefore is prohibited.

Frequency of Mental Retardation

· The best estimate is that only 1 percent of the population has mental retardation.

· Mental retardation in the United States is more common among the poor and, as a result, among

certain ethnic groups.

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Causes of Mental Retardation

1- Biological Abnormalities

About one-half of all cases of mental retardation are caused by known biological abnormalities.

i. Down syndrome

· The most common known biological cause of mental retardation is the chromosomal disorder

Down syndrome.

· The cause of Down syndrome is the presence of an extra chromosome.

· The incidence of Down syndrome is related to maternal age.

· In general, children and adults with Down syndrome function within the moderate to severe range

of mental retardation.

ii. Fragile-X syndrome

· Another chromosomal abnormality, fragile-X syndrome, is the most common known genetic cause

of mental retardation.

· Fragile-X syndrome is indicated by a weakening or break on one arm of the X sex chromosomes,

and it is transmitted genetically.

· Not all children with the fragile-X abnormality have mental retardation.

iii. Phenylketonuria

· Phenylketonuria or PKU, is one of these.

· PKU is caused by abnormally high levels of the amino acid phenylalanine, usually due to the absence

of or an extreme deficiency in phenylalanine hydroxylase, an enzyme that metabolizes phenylalanine.

· Retardation typically progresses from the severe to profound range.

· Fortunately, PKU can be detected by blood testing in the first several days after birth.

2- Infectious Diseases

· Mental retardation can also be caused by various infectious diseases.

· Damaging infections may be contracted during pregnancy, at birth, or in infancy to early childhood.

i. Rubella (German measles) is a viral infection that may produce few symptoms in the mother but can

cause severe mental retardation and even death in the developing fetus.

ii. The human immunodeficiency virus (HIV) can be transmitted from an infected mother to a

developing fetus.

· The effects on the child are profound, including mental retardation, visual and language

impairments, and eventual death.

iii. Syphilis is a bacterial disease that is transmitted through sexual contact.

· Infected mothers can pass the disease to the fetus.

· If untreated, syphilis produces a number of physical and sensory handicaps in the fetus, including

mental retardation.

· One infectious disease that occurs after birth meningitis can cause mental retardation.

3- Environmental Toxins

· Exposure to a variety of environmental toxins can also cause mental retardation.

· Both legal and illegal drugs pose a risk to the developing fetus.

· Toxins also present a potential hazard to intellectual development after birth.

4- Pregnancy and birth complications

· Pregnancy and birth complications also can cause mental retardation.

· One major complication is Rh incompatibility.

· Another pregnancy and birth complication that can cause intellectual deficits is premature birth.

· Other pregnancy and birth complications that can cause mental retardation include extreme

difficulties in delivery, particularly anoxia, or oxygen deprivation; severe malnutrition; and the seizure

disorder epilepsy.

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5- Cultural-familial Retardation

· As the term suggests, cultural-familial retardation tends to run in families and is linked with

poverty.

· A controversial issue is whether this typically mild form of mental retardation is caused primarily by

genes or by psychosocial disadvantage.

· Grossly abnormal environments can produce gross abnormalities in intelligence.

· Cultural-familial retardation is found far more frequently among the poor.

· Part of this is explained by the fact that lower intelligence causes lower social status.

· Impoverished environments lack the stimulation and responsiveness required to promote children's

intellectual and social skills throughout their development.

Treatment: Prevention and Normalization

Three major categories of intervention are essential in the treatment of mental retardation.

· First, many cases of both organic and cultural-familial mental retardation can be prevented through

adequate maternal and child health care, as well as early psycho-educational programs.

· Second, educational, psychological, and biomedical treatments can help people with mental

retardation to raise their achievement levels.

· Third, the lives of people with mental retardation can be normalized through mainstreaming in

public schools and promoting care in the community.

The availability and use of good maternal and child health care is one major step toward the

primary prevention of many biological causes of mental retardation.

Planning for childbearing can also help prevent mental retardation.

Early social and educational interventions can lead to the secondary prevention of cultural-familial

retardation.

The most important current secondary prevention is

i. Careful assessment early in life is critical to tertiary prevention.

ii. Medical screening is essential for detecting conditions like PKU.

iii. Accurate detection is important, because early interventions can help.

iv. Treatment of the social and emotional needs of people with mental retardation may include teaching

basic self-care skills, such as feeding, toileting and dressing, during the younger ages and various "life-

survival" skills at later ages.

v. Medical care for physical and sensory handicaps is also critical in the treatment of certain types of

mental retardation. Medication is not especially helpful in treating the intellectual or socio-emotional

problems of people with mental retardation.

vi. Normalization means that people with mental retardation are entitled to live as much as possible like

other members of society. The major goals of normalization include mainstreaming children with

mental retardation into public schools and promoting a role in the community for adults with mental

retardation.

For many children with mental retardation, the least restrictive environment means mainstreaming them

into regular classrooms.

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