• Genetic causes include Down syndrome, which results from the child having an extra copy of chromosome 21, and fragile X syndrome, which results from an abnormal X chromosome.

• Metabolic disorders are problems in breaking down or disposing of certain chemicals in the body. For example, phenylketonuria (PKU) is a metabolic disorder that can cause brain damage and mental retardation unless the diet is modified to restrict intake of a substance called phenylalanine.

• Infections during pregnancy can increase the risk of delivering a baby with mental retardation. Viruses like rubella can cause mental retardation in addition to hearing and visual problems in the baby.

• Drinking alcohol during pregnancy can cause fetal alcohol spectrum disorder (FASD). Children with FASD have a range of physical problems and mental retardation. Taking certain other drugs during pregnancy can sometimes cause mental retardation.

• Damage to the brain after birth due to lack of oxygen, physical trauma or malnutrition can cause mental retardation.

Prevention

Not all types of mental retardation can be prevented, but some can. For some mental retardation syndromes, genetic testing before conception can let parents know their chances of passing certain genes on to their children. Just because a parent carries a particular gene associated with retardation does not necessarily mean that his or her children will be mentally retarded. Talking to a genetic counselor can help parents make decisions about having children and about further testing.

• Keep immunizations (yours and your children's) up to date.

• Eat nutritious, balanced meals during pregnancy. Take a multivitamin and have regular prenatal care.

• Do not drink alcohol or do drugs while pregnant or if you may become pregnant.

• Get genetic counseling if you have a family history of a genetic disorder.

• Make sure children wear helmets when participating in certain sports such as biking or skating.

Quality of Life

Children with mental retardation can lead fulfilling lives. Early intervention programs can help children with mental retardation acquire basic self-care and socialization skills. Children with mental retardation may be placed in classrooms with their peers without mental retardation and receive special help from classroom aides. Depending on the severity of their mental retardation, adults with mental retardation may live alone, with roommates, or in group homes with some supervision, based on how much help they need. Severely mentally retarded adults may live in community care homes that provide daily supports.

For More Information

American Association on Mental Retardation (AAMR)
(800) 424-3688
www.aamr.org

National Information Center for Children and Youth with Disabilities
(800) 695-0285
www.nichcy.org

The Arc
(301) 565-3842
www.thearc.org

Inform Yourself

To find this and previous JAMA Patient Pages, go to the Patient Page index on JAMA's Web site at www.jama.com.

Sources: American Association on Mental Retardation, American Psychiatric Association, Centers for Disease Control and Prevention, National Information Center for Children and Youth with Disabilities

Sharon Parmet, M.A., Writer
Cassio Lynm, M.A., Illustrator
Richard M. Glass, M.D, Editor