Disorder that appears before adulthood noted by impaired cognitive functioning. This consists of both mental functioning and the ability for the individual to function in their environment. 

Intellectual disability is characterized by behavior. Characteristics include: delays in language development, memory skill deficits, difficultly learning social cues, difficulty with problem- solving, delays in self-care skills, and lack of social inhibitors. Those with intellectual disability often require more time to learn, with more repetition. 

Intellectual disability is a spectrum, ranging from mild to severe. There are differences between intellectual disabilities and learning disabilities or behavioral disorders, and they should not be confused with one another. Causes of intellectual disability include genetics, issues during pregnancy, issues at birth, other health problems, or traumatic brain injury during a person's life.