Diagnosis of an Intellectual Disability

The purpose of establishing a diagnosis of intellectual disability is to determine eligibility in order to receive various services and supports, and to ensure rights are protected, including:

  • Special education services
  • Home and community-based waiver services
  • Social Security Administration benefits
  • Specific treatment within the criminal justice system (e.g., In 2002, the U.S. Supreme Court ruled in Atkins v. Virginia that executing the mentally retarded violates the Eighth Amendment’s ban on cruel and unusual punishment).

Intellectual disability is diagnosed through the use of standardized tests of intelligence (testing a person’s I.Q.) and adaptive behavior (the ability of a person to function and perform everyday life activities).  The American Association on Intellectual and Developmental Disabilities (AAIDD) states the following must be present:

  1. Limitations in present functioning must be considered within the context of community environments typical of the individual’s age, peers and culture.
  2. Valid assessment considers cultural and linguistic diversity as well as difference in communication, sensory, motor and behavioral factors.
  3. Within an individual, limitations often coexist with strengths.
  4. An important purpose of describing limitations is to develop a profile of needed supports.
  5. With appropriate personalized supports over a sustained period, the life functioning of the person with intellectual disability generally will improve (AAMR, 2002).