Mental retardation

Introduction
Mental retardation is defined as sub average intelligence. The child has diminished learning capacity and does not adjust well socially. The degree of mental handicap is designated mild (IQ levels of 51-70), moderate (IQ levels of 21-35) and severe (IQ levels of 0-20). The IQ levels of 71-90 is designated as borderline intelligence and is not included in mental handicap. However, all levels of mentally retarded children are educable and trainable to some extent. In the general population, 2-3 percent of children have IQ below 70. Nearly three-fourth of such cases are mildly handicapped. About 4 per thousand of the general population are more severely handicapped with IQ below 50.

Causes of Mental retardation:
Mental retardation is due to interplay of several biomedical, socio-cultural and psychological factors. It is often difficulty to incriminate only a single factor as the cause of mental retardation. Majority of the cases of mental retardation are idiopathic (no cause can be identified). Specific factors may be described under three headings viz., prenatal (during pregnancy), natal (during birth), and postnatal (after birth).

Prenatal causes:
• Metabolic conditions in the fetus like phenylketonuria, Galactosemia, Mucopolysaccharidosis.
• Neurodegenerative disorders
• Chromosomal disorders like Down's syndrome, Klinfelter syndrome
• Tuberous sclerosis.
• Cretinism
• Maternal conditions like drug abuse, intrauterine infections, placental insufficiency or exposure to radiation during pregnancy.

Natal factors:
• Birth injuries
• Hypoxic, ischemic encephalopathy
• Intracerebral hemorrhage

Post natal factors:
• Infections of the central nervous system
• Head injuries
• Post vaccination encephalopathies
• Jaundice
• Hypoglycemia
• Hypoxia
• Malnutrition
• Iron deficiency
• Child abuse
• Autism.

Predisposing factors for mental retardation:
Low socio economic status, low birth weight, advanced maternal age and consanguinity of parents are associated with an increased risk for mental retardation in the children.

Symptoms of mental retardation in children:
Children present with learning disabilities, hyperactivity, and short span of attention, distractibility, poor concentration, poor memory, impulsiveness, awkward clumsy movements, disturbed sleep, emotional instability and low frustration tolerance. Associated defects of the bone, muscle, vision, speech and hearing are often found in the mentally handicapped children. Congenital birth defects, apart from the neurological system may be found if the cause if prenatal. Convulsions (fits) are common in the mentally handicapped children.

Diagnosis of Mentally retarded children:
A complete general and neurological examination must be carried out by the physician. IQ testing should be done. Down's syndrome, cretinism and other conditions should be ruled out. Urine tests for metabolic disease like phenylketonuria and galactosemia are done in familial cases of mental retardation. Investigations to rule out hypothyroidism are also done. Radiological investigations like CT and MRI scans are helpful in revealing brain abnormalities like leukodystropies, cerebral atrophy, hydrocephalus, tuberous sclerosis and other conditions.

Prevention of Mental retardation:

• Genetic counseling: Risk of recurrence in autosomal recessive disorders is high in consanguineous marriages. The parents should be informed about the possibility of prenatal diagnosis. Mothers older than 35 years should have antenatal screening for Down's syndrome.
• Rubella vaccine should be given to all girls to prevent this infection in first trimester of pregnancy.
• During preganacy teratogenic drugs, hormones, iodides and antithyroid drugs should be avoided. Mothers should be protected from contact with patients suffering from viral illness.
• During labor, good obstetric supervision is essential to prevent occurrence of birth injuries.
• Neonatal infection of the central nervous system should be diagnosed early and treated promptly. Jaundice should be managed correctly. Iron deficiency should be treated in the early childhood.

Management of mentally retarded children:
The parents should be counseled together. The diagnosis of the child should be fully explained to them, and also the prognosis. Principles of management should be explained in detail. Parental feelings and the home situation should also be discussed. The mentally retarded child needs the same basic care as any other child. Physiotherapy is often also needed. Anticonvulsant treatment is prescribed for seizures. Specific management of metabolic and endocrine disease should be done. The children need warmth, love and appreciation, as well as discipline. Institutionalization should be avoided. Day care centers and schools and integrated schools are useful.

Did you know?
Mental retardation is due to interplay of several biomedical, socio-cultural and psychological factors. It is often difficulty to incriminate only a single factor as the cause of mental retardation. Majority of the cases of mental retardation are idiopathic (no cause can be identified).