intellectual and developmental disabilities
Last updatedDefinition
Intellectual and developmental disabilities are disabilities that occur before the age of 18. Developmental disabilities can include physical and/or intellectual delays; the abbreviation IDD is sometimes used to signify that intellectual and other disabilities are present. Developmental disabilities include lifelong conditions such as cerebral palsy, Trisomy 21 (Down syndrome), and fetal alcohol spectrum disorders.
Intellectual disabilities affect a person’s intellectual, social, and practical functioning (or ability to learn at an expected level), defined as the daily skills needed to live and work in a community. They are distinct from learning disabilities such as dyslexia, which do not correlate to an individual’s overall intellectual functioning or affect daily living skills.
According to the American Psychiatric Association, people with intellectual disabilities may have lower cognitive capabilities in three areas: 1) Conceptual: language, reading, writing, math, reasoning, knowledge, memory skills, 2) Social: empathy, social judgment, communication skills, the ability to follow rules and the ability to make and keep friendships, and 3) Practical: independence in areas such as personal care, job responsibilities, managing money, recreation, and organizing school and work tasks.
In the past, an IQ of 75 or lower was used as an approximation for an intellectual disability, though the American Psychiatric Association now calls for a clinical diagnosis as IQ results “may not accurately reflect overall intellectual functioning.”
Although it may seem like an obvious slur now, “mental retardation” was the acceptable phrase used in federal programs until 2010. Euphemisms like “special,” “special needs,” or “intellectually challenged” are vague and may be perceived as patronizing, though these words still appear in common phrases like “special education” and Special Olympics. In the case of the former, some activists advocate for the use of terms such as inclusive education or unmet educational needs. Language such as “has a developmental disability” or specifying the disability are straightforward and helpful for clarity.
Because intellectual disabilities specifically begin in childhood, an adult who experienced a loss in intellectual functioning and adaptive skills later in life would be described as having a neurocognitive disability, or with the specific medical term for their condition (for example, “lives with the effects of a traumatic brain injury”).
Additional resources
- Facts about Intellectual Disability (Centers for Disease Control and Prevention)
- American Association on Intellectual and Developmental Disabilities (AAIDD)
- Inclusive Language for Talking About People with Intellectual Disabilities (Special Olympics)
- Learn More About DD (National Association of Councils on Developmental Disabilities)
Summary
Intellectual and developmental disabilities are disabilities that occur before the age of 18. Developmental disabilities can include physical and/or intellectual delays; the abbreviation IDD is sometimes used to signify that intellectual and other disabilities are present. Developmental disabilities include lifelong conditions such as cerebral palsy, Trisomy 21 (Down syndrome), and fetal alcohol spectrum disorders. Euphemisms like “special,” “special needs,” or “intellectually challenged” are vague and may be perceived as patronizing; language such as “has a developmental disability” or specifying the disability is straightforward and helpful for clarity.