Levels of Intellectual Disability
Level | IQ Range | Ability at Preschool Age (Birth to 6 Years) | Adaptive Skills at School Age (6 to 20 Years) | Support Required at Adult Age (21 Years and Older) |
|---|---|---|---|---|
Mild | IQ 52–69 | Often presents as speech–language delay Often not diagnosed until later age Can develop social and communication skills | Some difficulty learning reading, writing, and math, but can learn up to about the 6th-grade level by late adolescence Challenges making plans and managing money Socially immature but can be expected to learn appropriate social skills Some limitation of judgment and understanding of risk—more easily manipulated by others | Needs guidance and assistance in complex tasks (such as health care and legal decisions) and during times of unusual social or economic stress Can usually achieve enough social and vocational skills for self-support |
Moderate | IQ 36–51 | Poor social awareness Can profit from training in self-help Can talk or learn to communicate | With support, can progress to elementary school level in schoolwork May learn to travel alone in familiar places Social judgment and understanding limited but can learn some social and occupational skills May have successful friendships and romantic relationships | Cares for simple personal and household needs after extended guidance Needs supervision and guidance managing money, scheduling, and all but simplest daily tasks May achieve self-support by doing unskilled or semiskilled work in a supportive environment |
Severe | IQ 20–35 | Able to learn some self-help skills Has limited speech skills Can say a few words | Can talk or learn to communicate about simple, everyday events and learn simple health habits Little understanding of written language, numbers, time, or money Benefits from habit training Usually successful relationships with family members and familiar others Sometimes maladaptive behavior (including self-injury) | Can develop some useful self-protection skills in controlled environments Requires support for all daily tasks but may contribute partially to self-care under complete supervision |
Profound | IQ 19 or below | May need nursing care due to limited self-care skills Extreme cognitive limitation Often sensory and/or physical impairments | Limited understanding of speech or gestures; communicates mainly nonverbally Enjoys company of well-known family and caretakers, but sensory and physical impairments often limit social activities | Often needs nursing care May have very limited participation in self-care |