What is the cause of mental retardation?

What is the cause of mental retardation?
What is the cause of mental retardation?

Genetic abnormalities, maternal illnesses, psychosocial circumstances, drug exposure, and ambient chemical exposure are all known causes of mental retardation. The following are some of the known risk factors for MR:

  • Down’s Syndrome, phenylketonuria, and other genetic diseases
  • During pregnancy, several maternal illnesses can occur (e.g. rubella)
  • During pregnancy, a mother who abuses substances such as alcohol
  • Several psychosocial issues (e.g. problems with caregiving, low socioeconomic status, low parental education)

The oversimplified dispute over “organic” vs “environmental” causes of retardation has been rejected due to the growing scientific information base.


Incomplete general development of mental capacity. The child’s intelligence is impaired early in life and remains inadequately developed throughout theⁿ growth period. All aspects of intelligence are impaired. It does not include adults who by accident become mentally abnormal. The incidence is about three percent of the population and occurs more in males than in females.

cause of mental retardation

Doctors aren’t always able to pinpoint the exact cause of ID, but it can include:
  • An illness or exposure to alcohol, narcotics, or other poisons prior to birth are examples of trauma.
  • oxygen deprivation or early delivery are examples of birth trauma.
  • phenylketonuria (PKU) and Tay-Sachs disease are examples of hereditary illnesses.
  • Down syndrome is an example of chromosomal abnormalities.
  • poisoning with lead or mercury
  • malnutrition or other dietary problems
  • Early childhood illnesses such as whooping cough, measles, or meningitis can be deadly.
  • damage to the brain


About 70% of the affected children have no obvious physical anomalies though they have a higher level of these than the general population.


(a) Maternal infections during pregnancy;

(b) Genetic factor;

(c) Maternal habits like drugs, alcohol, and smoking;

(b) Congenital abnormality;

(c) Metabolic disorders.

Perinatal or natal:-

(a) Birth asphyxia;

(b) Birth injury


(a) Infections like meningitis and encephalitis

(b) Kernicterus;

(C) Trauma;

(d) Poison;

(e) Abandoned children.

The scale for measuring intelligence is the Intelligent The average range is 90 – 110 Gifted children’s range is 115 – 150. Mentally retarded children score in the range below 80. They can be subclassified as


1. Educable or maroons = 50 – 70

2. Trainable or imbecile = 20 – 49

3. Total dependent or idiot = less than 20.

Most of the methods used to determine intelligence have four components

1. Comprehension;

2. Memory (recall);

3. ability to reason;

4. Abstract thinking.

Success in drawing and music does not correlate with intelligence. Reading and arithmetic are closely but not perfectly correlated with intelligence. Ability to spell correctly correlates highly with good general Intelligence but not always with general school grades. Mental testing measures the immediate efficiency of the individual in certain specific respects but does not measure native capacity for intellectual accomplishment. Success in an individual depends on the ability to learn and also on the opportunity to learn.

The capacity to learn depends on the genetic endowment, events in early life, and the degree of stimulation offered by the environment.


This is a very difficult thing to do. One has to be patient, understanding, and resourceful.

1. Treat treatable conditions.

2. Rehabilitate abandoned children.

3 Mild to moderate forms of mental retardation can be sent to special schools after psychometric tests have been done to determine their level of retardation.

4 Prevent causes before they occur.

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