Developmental disabilities are a diverse group of severe chronic conditions that are due to mental and/or physical impairments. People with developmental disabilities have problems with major life activities such as language, mobility, learning, self-help, and independent living. Developmental disabilities begin anytime during development up to 22 years of age and usually last throughout a person’s lifetime.
Intellectual disability is characterized by a significantly below-average score on a test of mental ability or intelligence and by limitations in the ability to function in areas of daily life, such as communication, self-care, and getting along in social situations and school activities. Intellectual disability is sometimes referred to as a cognitive disability or mental retardation.
Children with intellectual disability can and do learn new skills, but they develop more slowly than children with average intelligence and adaptive skills. There are different degrees of intellectual disability, ranging from mild to profound. A person's level of intellectual disability can be defined by their intelligence quotient (IQ), or by the types and amount of support they need.
People with intellectual disability may have associated physical disabilities as well. Examples of these coexisting conditions include visual impairment, hearing loss, speech and language problems, seizure disorder, and cerebral palsy. Children with intellectual disability also have a three- to four-fold greater risk of emotional and behavioral problems such as autism, ADHD, anxiety, and mood disorders. Children with severe intellectual disability are more likely to have additional disabilities than are children with mild Intellectual disability.