April 25, 2011

Mental Retardation

Mental Retardation: This is a condition in which there is delay or deficiency in all aspects of development, i.e. there is global and noticeable deficiency in the development of motor, cognitive, social, and language functions. This is the commonest form of developmental disability.


Continued infant-like behaviour

Decreased learning ability

Failure to meet the markers of intellectual development

Inability to meet educational demands at school

Lack of curiosity

Note: Changes to normal behaviours depend on the severity of the condition. Mild retardation may be associated with a lack of curiosity and quiet behaviour. Severe mental retardation is associated with infant-like behaviour throughout life.


Mental retardation affects about 1 - 3% of the population. There are many causes of mental retardation, but doctors find a specific reason in only 25% of cases.

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. Failure to adapt normally and grow intellectually may become apparent early in a child's life. In the case of mild retardation, these failures may not become recognizable until school age or later.

The degree of impairment from mental retardation varies widely, from profoundly impaired to mild or borderline retardation. Less emphasis is now placed on the degree of retardation and more on the amount of intervention and care needed for daily life.

Risk factors are related to the causes. Causes of mental retardation can be roughly broken down into several categories:

Infections (present at birth or occurring after birth)

Chromosomal abnormalities

Genetic abnormalities and inherited metabolic disorders



Trauma (before and after birth)

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: 







Below 20   

Exams and Tests

An assessment of age-appropriate adaptive behaviours can be made using developmental screening tests. The failure to achieve developmental milestones suggests mental retardation.

The following may be signs of mental retardation:

Abnormal Denver developmental screening test

Adaptive behaviour score below average

Development way below that of peers

Intelligence quotient (IQ) score below 70 on a standardized IQ test


The primary goal of treatment is to develop the person's potential to the fullest. Special education and training may begin as early as infancy. This includes social skills to help the person function as normally as possible.
It is important for a specialist to evaluate the person for other affective disorders and treat those disorders. Behavioural approaches are important for people with mental retardation.


The outcome depends on:


Other conditions

Personal motivation


Many people lead productive lives and function on their own; others need a structured environment to be most successful.


Genetic: Prenatal screening for genetic defects and genetic counselling for families at risk for known inherited disorders can decrease the risk of inherited mental retardation.

Social: Government nutrition programs are available to poor children in the first and most critical years of life. These programs can reduce retardation associated with malnutrition. Early intervention in situations involving abuse and poverty will also help.

Toxic: Environmental programs to reduce exposure to lead, mercury, and other toxins will reduce toxin-associated retardation. However, the benefits may take years to become apparent. Increased public awareness of the risks of alcohol and drugs during pregnancy can help reduce the incidence of retardation.

Infectious: The prevention of congenital rubella syndrome is probably one of the best examples of a successful program to prevent one form of mental retardation. Constant vigilance, such as limiting exposure to cat litter that can cause toxoplasmosis during pregnancy, helps reduce retardation that results from this infection.

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