Definition

The following section from the DCD Manual is remixed from the Minnesota Department of Education.

The American Association on Intellectual and Developmental Disabilities (AAIDD) defines Intellectual Disability as “a disability characterized by significant limitations both in intellectual functioning and in adaptive behavior as expressed in conceptual, social, and practical adaptive skills. This disability originates before age 18.” This definition has two key hallmarks: (1) intellectual disability involves needs in adaptive behavior, and not just intellectual functioning, and (2) persons with intellectual disability can progress. Examples of ID include autism, behavior disorders, brain injury, cerebral palsy, Down syndrome, fetal alcohol syndrome, intellectual disability, and spina bifida. You may notice an overlap with other disability areas, as people with ID often have complex needs that cross over and are within other disability categories.

Medical providers sometimes use the terms developmental delay and developmental delay disability to mean the same thing. They are not the same, though. People can outgrow or catch up from developmental delays. Developmental disabilities (also known as intellectual disabilities) are lifelong, though people can still make progress and thrive. Sometimes it is difficult to determine whether a young child has a delay or a disability. That is one reason doctors may use the words interchangeably. Even when it is unclear what is causing the delay, early intervention often helps children catch up (Vaughn & Bos, 2020).