Mental – health professionals classify patients into one of four levels of retardation.

Mild Mental Retardation:

  • IQ scores from 50 to 69.
  • Includes about 85 Percent of the mentally retarded population.
  • Individuals in this group can often live on their own with community support.

Moderate Mental Retardation:

  • IQ Scores between 35 and 50.
  • Includes about 10 percent of the mentally retarded population.
  • Individuals in this group can often lead relatively normal lives provided they receive some level of supervision. Such individuals often live in group homes with other mentally retarded people.

Severe Mental Retardation:

  • IQ scores between 20 and 35.
  • About 3 percent to 4 percent of the mentally retarded population.
  • Individuals in this category canoften master the most basic skills of living, such as cleaning and dressing themselves. They often live in group homes.

Profound Mental Retardation:

  • IQ scores of less than 20.
  • Includes about 1 percent to 2 percent of the mentally retarded population.
  • Individuals at this level can often develop basic communication and self – care skills. They often have other mental disorders.

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):

  • Congenital CMV
  • Congenital rubella
  • Congenital toxoplasmosis
  • Encephalitis
  • HIV infection
  • Listeriosis
  • Meningitis

Chromosomal abnormalities:

  • Environmental
  • Deprivation Syndrome
  • Genetic abnormalities and inherited metabolic disorders


  • Congenital hypothyroid
  • Hypoglycemia (Poorly regulated diabetes mellitus) is a condition that occurs when your blood sugar (glucose) is too low.
  • Reye syndrome: Reye syndrome is sudden (acute) brain damage (encephalopathy) and liver function problems of unknown cause.
  • The syndrome has occurred with the use of aspirin to treat chickenpox or the flu in children.However, it has become very uncommon since aspirin in no longer recommended for routine use in children.
  • Hyperbilirubinemia (very high bilirubin levels in babies. Bilirubin is a product that results from the breakdown of hemoglobin. Total and direct bilirubin are usually measured to screen for or to monitor liver or gallbladder problems.)


  • Malnutrition


  • Intracranial hemorrhage before or after birth.
  • Lack of oxygen to the brain before, during , or after birth.
  • Severe head injury.


The symptoms of mental retardation usually appear early in life. Children with the disorder tend to develop more slowly than normal. They may learn to sit up, to walk, to talk, and to perform Other simple tasks later than average. Mental retardation is often accompanied by other symptoms as well. These symptoms include aggression, a tendency toward self – injury , and personality changes. As a child grows older, the best indication of mental retardation is the standard intelligence tests.

  • Continued infantile behavior
  • Decreased learning ability
  • Failure to meet intellectual developmental markers
  • Inability to meet educational demands at school
  • Lack of curiosity

Changes to normal behaviors depend on the severity of the condition. Mild retardation may be associated with a lack of curiosity and quiet behavior. Severe mental retardation is associated with infantile behavior throughout life.


Genetic: Prenatal screening for genetic counseling for families at risk for known heritable disorders can decrease the incidence of genetically caused mental retardation.
Social: Government programs to ensure adequate nutrition are available to the underprivileged in the first and most critical years of life. These programs can reduce retardation associated with malnutrition. Early intervention in situations involving abuse and deprivation will also help.

The child was always seen isolated from the group and made no attempt to join in the fun and frolic of the other children. On further probing it was found that there were a number of such children in and around Special education, The result was the establishment of Vidivelli in 1987 . A school for the mentally challenged children by the management Sisters of St. Anne,s Trichy.

  • Early Intervention Program
  • Academic skills Training
  • Vocational Training and Rehabilitation
  • Counselling for Parent