retardation
Prenatal Mental illnesses and issues
Fetal alcohol syndrome (FAS) affects one in 3,000 children in Western countries. It is caused by
the mother's heavy drinking during the first twelve weeks (trimester) of pregnancy. Some studies
have shown that even moderate alcohol use during pregnancy may cause learning disabilities in
children. Drug abuse and cigarette smoking during pregnancy have also been linked to mental
retardation.
Maternal infections and such illnesses as glandular disorders, rubella, toxoplasmosis, and
cytomegalovirus (CMV) infection may cause mental retardation. When the mother has high
blood pressure (hypertension) or blood poisoning (toxemia), the flow of oxygen to the fetus may
be reduced, causing brain damage and mental retardation.
Birth defects that cause physical deformities of the head, brain, and central nervous system
frequently cause mental retardation. Neural tube defect, for example, is a birth defect in which
the neural tube that forms the spinal cord does not close completely. This defect may cause
children to develop an accumulation of cerebrospinal fluid inside the skull (hydrocephalus).
Hydrocephalus cause can learning impairment by putting pressure on the brain.
Childhood illnesses and injuries
Hyperthyroidism, whooping cough, chickenpox, measles, and Hib disease (a bacterial infection)
may cause mental retardation if they are not treated adequately. An infection of the membrane
covering the brain (meningitis) or an inflammation of the brain itself (encephalitis) can cause
swelling that in turn may cause brain damage and mental retardation. Traumatic brain injury
caused by a blow to the head or by violent shaking of the upper body may also cause brain
damage and mental retardation in children.
Environmental factors
Ignored or neglected infants who are not provided with the mental and physical stimulation
required for normal development may suffer irreversible learning impairment. Children who live
in poverty and suffer from malnutrition, unhealthy living conditions, abuse, and improper or
inadequate medical care are at a higher risk. Exposure to lead or mercury can also cause mental
retardation. Many children have developed lead poisoning from eating the flaking lead-based
paint often found in older buildings.