Intellectual Disability

What is an Intellectual Disability?

Intellectual disabilities are disabilities that occur during the developmental period and are characterised by below average intellectual and adaptive functioning. People with intellectual disabilities typically have an IQ of below 70 and often experience difficulties learning and processing information, grasping abstract concepts, understanding the subtleties of interpersonal interactions, and manipulating the ideas and concepts required for planning and organisation.

Intellectual disabilities are considered chronic and often co-occur with other mental conditions including depression, attention-deficit/hyperactivity disorder, and autism spectrum disorder.

Intellectual disabilities can impact on:

  • The conceptual domain. Including knowledge, memory, language, reading, writing, math and reasoning skills.
  • The social domain. Including interpersonal communication skills, social judgment, the ability to make and retain friendships and the capacity for empathy.
  • The practical domain. Including personal care, job responsibilities, money management, recreation, and organization of school and work tasks.

DSM-5 Diagnostic Criteria for Intellectual Disabilities

  • Deficits in intellectual functioning such as reasoning, problem solving, planning, abstract thinking, judgment, academic learning, and learning from experience, confirmed by both clinical assessment and individualized, standardized intelligence testing.
  • Deficits in adaptive functioning that result in failure to meet developmental and sociocultural standards for personal independence and social responsibility. Without ongoing support, the adaptive deficits limit functioning in one or more activities of daily life, such as communication, social participation, and independent living, across multiple environments, such as home, school, work and the community.
  • Onset of intellectual and adaptive deficits during the developmental period.