What is an Intellectual Disability?

Intellectual disability definition plus in-depth, trusted information on intellectual disabilities as defined in the new DSM-5.

The term, intellectual disability, refers to a condition in which a person has certain limitations in intellectual functions like communicating, taking care of him- or herself, and has impaired social skills. These limitations cause a child to intellectually develop more slowly than other children. These children may take longer to walk, talk, and take care of themselves than the typical, unimpaired, child. It's probable that children with intellectual disabilities will have difficulty learning in school. (Intellectual and Learning Disabilities in Children, Students) They do learn; it just takes them longer. Even so, certain things will likely prove impossible for some of these children to learn.

Intellectual Disability Definition

Has the intellectual disability definition changed in DSM-V? Yes and no. In the past, experts and mental health professionals used the term mental retardation to describe an intellectual disability and it was the term used in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). But over the past 20 years or so, mental health experts and other professionals have increasingly begun to use the term, intellectual disability. This term better describes the scope and reality of an intellectual developmental disorder and replaces the term mental retardation in the new DSM-V.

Experts define intellectual disability as:

"...significantly subaverage general intellectual functioning, existing concurrently with deficits in adaptive behavior and manifested during the developmental period, that adversely affects a child's educational performance." ~Rosa's Law, signed by President Obama in October 2010.

More information on the types of intellectual disabilities, including examples, can be found here.

Are Intellectual Disabilities Common?

Intellectual disabilities represent the most common developmental disability. About 6.5 million Americans have an intellectual disability. Over 545,000 children between the ages of 6 and 21 have some type of intellectual disability and need special education services in public school. Even though these statistics indicate that it's a fairly common mental disorder, some kids have a very low level of impairment, while others have a very high level. (Mild, Moderate, Severe Intellectual Disability Differences) So, depending on the level of disability, doctors and other professionals may not recognize a child has an intellectual impairment. Children with very low, barely detectable intellectual disability may get along in a typical education program, but others will likely need special education services to learn basic life skills.

Intellectual Disability in Children

What does an intellectual disability look like in children? Intellectual disabilities manifest in a variety of ways. For instance, intellectually impaired children may:

  • Sit up, crawl, or walk later
  • Talk later
  • Have trouble remembering
  • Have difficulty with social rules
  • Have difficulty understanding consequences of actions
  • Have trouble solving problems and thinking logically

Kids with intellectual disabilities may have impairments in:

  • Reasoning
  • Planning
  • Abstract thought
  • Judgment
  • Academic judgment
  • Experiential learning

Mental health professionals measure these skills through IQ testing and applying clinical judgment to interpret IQ, rather than relying solely on IQ scores for assessing level of impairment. IQ tests used to measure these intellectual abilities must be standardized and given by a professional certified in IQ testing. If you suspect that your child has an intellectual developmental disorder, consult a mental health professional and speak candidly about your concerns. Many of these children lead full and happy lives when they receive the proper care and help.

article references



next: Intellectual Disability: Causes and Characteristics
~ all intellectual disability articles
~ all neurodevelopmental disorders articles

Last Updated: 08 August 2016
Reviewed by Harry Croft, MD

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