What is an Intellectual Disability?

People with an intellectual disability have difficulties with thought processes, learning, communicating, remembering information and using it appropriately, making judgements, and problem solving.

An intellectual handicap is present if the level of intellectual functioning is significantly lower than average and there are limitations in two or more adaptive skills, in the areas of communication, self-care, home living, social skills, community use, self direction, health and safety, leisure and work.

The identification of intellectual functioning is largely based upon the intelligence quotient (IQ) test. Using this test, scores of 90 through to 109 are classified as average. People who score less than 70 may be considered to be handicapped by an intellectual disability depending on how well they function in key areas of everyday life.

An intellectual disability may become apparent early in life or in the case of people with a mild intellectual disability, not be diagnosed until school age or later.

Many people with an intellectual disability also have physical disabilities.

Source: Alessandri, L.M., Leonard, H., Blum, L.M.,Bower, C. Disability Counts: a profile of disability in Western Australia. West Perth: Disability Services Commisson, 1996.

Other discussions about intellectual disability may be found at:

Activ Foundation. What is an intellectual disability?

Australian Institute of Health and Welfare. The definition and prevalence of intellectual disability in Australia

Better Health Channel. Intellectual disability - facts and figures.

Children, Youth and Women's Health Service (CYWHS). Intellectual disability

Australian Psychological Society. Psychologists and intellectual disability