Intellectual Disability (Mental Retardation)
What causes intellectual disability?
Anytime something interferes with normal brain development, intellectual disability can result. However, a specific cause for intellectual disability can only be pinpointed about a third of the time.
The most common causes of intellectual disability are:
Genetic conditions. These include things like Down syndrome and fragile X syndrome.
Problems during pregnancy. Things that can interfere with fetal brain development include alcohol or drug use, malnutrition, certain infections, or preeclampsia.
Problems during childbirth. Intellectual disability may result if a baby is deprived of oxygen during childbirth or born extremely premature.
Illness or injury. Infections like meningitis, whooping cough, or the measles can lead to intellectual disability. Severe head injury, near-drowning, extreme malnutrition, exposure to toxic substances such as lead, and severe neglect or abuse can also cause it.
Can intellectual disability be prevented?
Certain causes of intellectual disability are preventable. The most common of these is fetal alcohol syndrome. Pregnant women shouldn’t drink alcohol. Getting proper prenatal care, taking a prenatal vitamin, and getting vaccinated against certain infectious diseases can also lower the risk that your child will be born with intellectual disabilities.
In families with a history of genetic disorders, genetic testing may be recommended before conception.
Certain tests, such as ultrasound and amniocentesis, can also be performed during pregnancy to look for problems associated with intellectual disability. Although these tests may identify problems before birth, they cannot correct them.
How is intellectual disability diagnosed?
Intellectual disability may be suspected for many different reasons. If a baby has physical abnormalities that suggest a genetic or metabolic disorder, a variety of tests may be done to confirm the diagnosis. These include blood tests, urine tests, imaging tests to look for structural problems in the brain, or electroencephalogram (EEG) to look for evidence of seizures.
In children with developmental delays, the doctor will perform tests to rule out other problems, including hearing problems and certain neurological disorders. If no other cause can be found for the delays, the child will be referred for formal testing.
Three things factor into the diagnosis of intellectual disability: interviews with the parents, observation of the child, and testing of intelligence and adaptive behaviors. A child is considered intellectually disabled if he or she has deficits in both IQ and adaptive behaviors. If only one or the other is present, the child is not considered intellectually disabled.
After a diagnosis of intellectual disability is made, a team of professionals will assess the child’s particular strengths and weaknesses. This helps them determine how much and what kind of support the child will need to succeed at home, in school, and in the community.