Intellectual disability (formerly called mental retardation) is a decreased ability to think and learn. It’s caused by a problem with how the brain works.

The diagnosis is based on intelligence quotient (IQ) tests and a child's learning problems.

The disability can range from mild to severe. People who have intellectual disability may have a hard time with:

• Learning, especially complex tasks.
• Language.
• Self-care (in cases of severe intellectual disability).