How many people are affected by an intellectual disability (formerly referred to as mental retardation)?
Studies have shown that somewhere between one and three percent of Americans have an intellectual disability, depending on how they are counted. Based on an IQ score alone, the percentages would be closer to 3 percent. It is difficult to pinpoint exactly how many people have an intellectual disability. Studies alone may not identify everyone. Many school age children receive a diagnosis of learning disability, developmental delay, behavior disorder, or autism instead of mental retardation.
