Intellectual Disabilities (ID)

What is ID?

Intellectual disability (ID) is a neurodevelopmental condition that entails limitations in both intellectual functioning AND adaptive behaviour.

  • Intellectual Functioning refers to general mental capacity, which includes essential processes like learning, reasoning, problem-solving, etc.
  • Adaptive Behaviour comprises three skill types – conceptual skills (e.g., literacy, mathematics, judgment), social skills (e.g., interpersonal communication, empathy), and practical skills (e.g., activities of daily living like eating, dressing).

Historically, ID was termed “mental retardation,” but this is no longer in use due to its negative connotation, which can engender misunderstandings about the condition and the experience of individuals with this condition. While ID is the preferred term, it takes time for legislation, regulatory boards and organizations to adapt to this change in language.


Symptoms of ID originate before the age of 18, which is also typically when a diagnosis would be given. This also covers individuals who were previously diagnosed with mental retardation in number, kind, level, type and duration of disability.

Individuals with ID often struggle with speaking, reading, eating, taking care of themselves, or interacting appropriately with others. Deficits in emotional and behavioural regulation are also closely associated with ID which disrupt the adult’s daily life and functioning. Physical problems such as seizures, seeing, hearing, or verbalizing may also be present.

Most adults with intellectual disabilities however can learn a great deal and may have partially or even fully independent lives.