Mental Retardation Fact Sheet

Definition: A condition that appears before age 18 in which intelligence is significantly below average (below 70 – 75), and functional skills and social behaviors do not meet what is expected for the person’s age and culture.

Mental retardation cuts across the lines of racial, ethnic, educational, social and economic backgrounds. It can occur in any family. One out of ten American families is directly affected by mental retardation.

Approximately 555,400 Texans have mental retardation and 20,000 of these individuals have severe or profound mental retardation.

There are approximately 25,000 children and adolescents with mental retardation and 2,700 children and adolescents with multiple disabilities in the Texas school system.

What are the causes of mental retardation? Mental retardation can be caused by any condition which impairs development of the brain before birth, during birth or in the childhood years. Several hundred causes have been discovered, but in about one-third of the people affected, the cause remains unknown. The three major known causes of mental retardation are Down Syndrome, Fetal Alcohol Syndrome and Fragile X.

The causes can be categorized as: genetic, problems during pregnancy, problems at birth, problems after birth and poverty and cultural deprivation.

Genetic – Abnormality of genes inherited from parents, errors when genes combine or from other disorders of the genes caused during pregnancy by infections, overexposure to x-rays and other factors. More than 500 genetic diseases are associated with mental retardation. Some examples include PKU, Down Syndrome and Fragile X Syndrome.

Problems during pregnancy – Use of alcohol or drugs by the mother. Other risk factors can include smoking, malnutrition and other specific illnesses during pregnancy.

Problems at birth – A birth condition of unusual stress which injures the infant’s brain.

Problems after birth – Some childhood diseases can damage the brain, as can accidents which cause head trauma. Certain environmental toxins such as lead or mercury can cause irreparable damage.

Poverty and cultural deprivation – Children may develop mental retardation due to malnutrition, disease-producing conditions, inadequate medical care and environmental health hazards.

Mental retardation is ten times more common that Cerebral Palsy and 28 times more prevalent than neural tube defects such as Spina Bifida. It affects 25 times as many people as blindness.
The effects of mental retardation vary considerably among people, just as the range of abilities varies considerably among people who do not have mental retardation. About 87% will be mildly affected and will be only a little slower than average in learning new information and skills. As children, their mental retardation is not readily apparent and may not be identified until they enter school. As adults, many will be able to lead independent lives in the community.

During the past 30 years, significant advances in research have prevented many cases of mental retardation. Early comprehensive prenatal care and preventative measures prior to and during pregnancy increase a woman’s chances of preventing mental retardation. Today’s research is opening new insights into the causes, treatment and possible prevention of mental retardation and bringing new hope to the lives of persons with mental retardation.