What is mental retardation?

The American Association on Mental Retardationdefines mental retardation as a disability that significantly limits both intelligence and social adaptive behavior before the age of 18. Mental retardation is not a physical disease or a mental illness. However, mental retardation may coexist with a mental illness and may be caused by a variety of factors, including genetic disorders, complications during pregnancy and right after childbirth, injury, disease, brain abnormality, and exposure to toxic or poisonous chemicals. According to a recent study conducted by the Centers for Disease Control and Prevention (CDC), mental retardation is the most common developmental disorder in the United States and affects an estimated 1.5 million children and adults between the ages of 6 and 64.