Intellectual disability

Intellectual disability, also disorder of intellectual development

and known as learning difficulty (in the United Kingdom and different from learning disability), is a generalized neurodevelopmental disorder characterized by significant impairment in intellectual and adaptive functioning. Intellectual disabilities may first be apparent during school age. The causes of the disability may be either developmental or genetically inherited. Children with intellectual disability typically have an intelligence quotient (IQ) below 70 and deficits in at least two adaptive behaviors that affect everyday living.

According to the DSM-5, intellectual functions include reasoning, problem solving, planning, abstract thinking, judgment, academic learning, and learning from experience. Deficits in these functions must be confirmed by clinical evaluation and individualized standard IQ testing. On the other hand, adaptive behaviors include the social, developmental, and practical skills people learn to perform tasks in their everyday lives. Deficits in adaptive functioning often compromise an individual's independence and ability to meet their social responsibility. Age related deficits of memory and cognition can cause intellectual disability as seen in Alzheimer's disease and gerontological brain atrophy cases.

Intellectual disability is subdivided into syndromic intellectual disability, in which intellectual deficits associated with other medical and behavioral signs and symptoms are present, and non-syndromic intellectual disability, in which intellectual deficits appear without other abnormalities.