An intellectual disability (ID) can be described as an impairment to cognitive functioning. Intellectual disabilities, which originate before age 18 and are the most common type of developmental disability, may be mild to severe and are characterized by limitations in intellectual functioning and adaptive behavior such as social and practical skills.
In the past, the term mental retardation was used widely to refer to this condition. In 2010, President Obama signed Rosa's Law, a bill that required any instances of "mental retardation" to be gradually replaced with "intellectual disability" and "individual with an intellectual disability" in all federal policy.
Many other agencies followed suit, changing their terminology in response to requests from advocacy organizations that rejected the term "mental retardation" for its negative connotations and potential to generate misunderstanding about an individual's particular condition. The term has now fallen out of general use. By 2013, the Social Security Administration had replaced the term in the Listing of Impairments with the term "intellectual disability."
Between 1% and 3% of the population have some type of intellectual disability. An intellectual disability may be diagnosed if an individual shows cognitive limitations and experiences limitations to adaptive behavior.
An IQ test score that falls between 70 and 75 is another key indicator of an intellectual disability. Those who are diagnosed with this condition will typically experience some difficulty with general learning and may take longer to develop the skills necessary for everyday function.
Although there may be some life skills people intellectual disabilities are unable to learn, those diagnosed with an intellectual disability are still often able to attend school, obtain an education, and learn how attend to their personal needs. General learning typically takes longer and requires more repetition, but many people are able to learn the life skills necessary to live independently, such as find and maintain employment.
The fifth edition of the Diagnostic and Statistical Manual (2013) reflects the updated terminology for the condition adopted by many other official agencies. In the DSM, intellectual disability, or intellectual developmental disorder, is described as a condition marked by deficits in intellectual and adaptive functioning:
Some characteristics of intellectual disability in adults could include impaired ability to:
In order for these signs to lead to an ID diagnosis, they must be present during childhood or adolescence.
A child who is intellectually disabled may reach certain milestones of development later than children who are not similarly affected. For example, a child may stand and walk later than other children of the same age, be unable to see the consequences of actions, lack curiosity, display infant-like behavior past the age of infancy, and have difficulty in school.
Other characteristics of intellectual disability in children may include:
A child diagnosed with an ID may develop and learn at a slower pace than a child who does not have an ID, and it can take the child longer to learn language, self-care skills, and social skills. Intellectually disabled children are often still able to learn and achieve some level of function, especially with the help and support of a trained professional.
At one point, IQ was more heavily relied upon when diagnosing an intellectual disability and determining its severity. While the DSM-5 still recognizes these categories, more emphasis is placed on the skills associated with each level rather than their IQ:
Certain conditions may be associated with ID including:
While the conditions listed above are not types of intellectual disabilities, they may cause them.
Not all causes of intellectual disability are known. In about 75% of all cases diagnosed, doctors are not able to find a specific reason for the disability. Some known causes include:
While there is no cure for intellectual disability, they can be effectively managed. Learn more about treatment options for intellectual disabilities.
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