Lesson 3: Intellectual Disability

How is Intellectual Disability Diagnosed?

Intellectual disability is diagnosed by looking at two main things. These are the ability of a person’s brain to learn, think, solve problems, and make sense of the world (called IQ or intellectual functioning); and whether the person has the skills he or she needs to live independently (called adaptive behaviour, or adaptive functioning).

Intellectual functioning, or IQ, is usually measured by a test called an IQ test. The average score is 100. People scoring below 70 to 75 are thought to have intellectual disability. To measure adaptive behaviour, professionals look at what a child can do in comparison to other children of his or her age. Certain skills are important to adaptive behaviour. These are: daily living skills, such as getting dressed, going to the bathroom, and feeding one’s self; communication skills, such as understanding what is said and being able to answer; social skills with peers, family members, adults, and others. To diagnose intellectual disability, professionals look at the person’s mental abilities (IQ) and his or her adaptive skills.

Providing services to help individuals with intellectual disability has led to a new understanding of how we define intellectual disability. After the initial diagnosis of intellectual disability is made, we look at a person’s strengths and weaknesses. We also look at how much support or help the person needs to get along at home, in school, and in the community. This approach gives a realistic picture of each individual. It also recognizes that the “picture” can change. As the person grows and learns, his or her ability to get along in the world grows as well.