Mental Retardation

The American Association on Mental Retardation (AAMR) defines mental retardation as "significantly subaverage general intellectual function existing concurrently with deficits in adaptive behavior manifesting itself during the developmental period (before age 18). An estimated 1 % to 3% of the population is mentally retarded, demonstrating an IQ below 70 and an associated deficit in carrying out tasks required for personal independence.

Retardation commonly is accompanied by additional physical and emotional disorders that may constitute handicaps in themselves. Mental retardation places a significant burden on patients and their families, resulting in stress, frustration, and family problems.

Causes

The AAMR has grouped the causes of mental retardation into 10 categories. But a specific cause is identifiable in only 25% of retarded people and, of these, only 10% have the potential for cure through medical or surgical intervention. In the remaining 75%, predisposing factors, such as deficient prenatal or perinatal care, inadequate nutrition, poor social environment, and poor child-rearing practices, contribute significantly to mental retardation.

It's estimated that 10% to 15% of individuals with mental deficiency have a significant chromosome abnormality. This percentage is greater among individuals who have anatomic malformations. Prenatal screening for genetic defects (such as Thy-Sachs disease) and genetic counseling for families at risk for specific defects have reduced the incidence of genetically transmitted mental retardation.

Symptoms

• failure to meet intellectual developmental markers
• persistence of infantile behavior
• lack of curiosity
• decreased learning ability
• inability to meet educational demands of school

Note: Variations in normal adaptive 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.

Treatment

Effective management of a mentally retarded patient requires an interdisciplinary team approach that provides complete, continuous, and coordinated services. A primary goal is to develop the patient's strengths as fully as possible, taking into account his interests, personal experiences, and resources. Another major goal is the development of social adaptive skills to help the patient function as normally as possible.

Mentally retarded children require special education and training, ideally beginning in infancy. An individualized, effective education program can optimize the quality of life for even the profoundly retarded.

The prognosis for people with mental retardation is related more to timing and aggressive treatment, personal motivation, training opportunities, and associated conditions than to the mental retardation itself. With good support systems, many mentally retarded people become productive members of society. Successful management leads to independent functioning and occupational skills for some and a sheltered environment for others.

Prevention

Immunization against diseases such as measles and Hib prevents many of the illnesses that can cause mental retardation. In addition, all children should undergo routine developmental screening as part of their pediatric care. Screening is particularly critical for those children who may be neglected or undernourished or may live in disease-producing conditions. Newborn screening and immediate treatment for PKU and hyperthyroidism can usually catch these disorders early enough to prevent retardation.

Good prenatal care can also help prevent retardation. Pregnant women should be educated about the risks of drinking and the need to maintain good nutrition during pregnancy. Tests such as amniocentesis and ultrasonography can determine whether a fetus is developing normally in the womb.