What are the causes of mental retardation?
Mental retardation can occur at anytime before a child reaches the age of 18 years old. It can happen before the child is born or during childhood. Causes of mental retardation include injury, disease, or a brain abnormality. For many children, the cause of their mental retardation may never be known. Some of the most common known causes of mental retardation that occur before a child is born are fetal alcohol syndrome, Down syndrome, and fragile X syndrome. Other conditions that affect an unborn child include genetic abnormalities, infections, or birth defects that affect the brain (such as hydrocephalus). Other causes of mental retardation (such as asphyxia) happen while a baby is being born or soon after birth. Still other causes of mental retardation do not happen until a child is older. These may include serious head injury, stroke, or certain infections such as meningitis. Some metabolic conditions, such as phenylketonuria (PKU), galactosemia, and congenital hypothyroidism, can c
