Intellectual disability (ID)

Intellectual disability (ID) is a diagnosis given when an individual has problems both in intellectual functioning (i.e., ability to learn, reason, make decisions, and solve problems) and adaptive functioning (i.e., the ability to function in everyday activities). 


Typically diagnosed before the age of 18, an individual with ID may have problems speaking, reading, eating, taking care of themselves, or interacting appropriately with others. People with ID can and do learn new skills, but they learn them more slowly. 


Severity of ID

ID has different severity levels based on adaptive functioning in the conceptual, social, and practical domains.

  1. Conceptual: language, reading, writing, math, reasoning, knowledge, memory
  2. Social: empathy, social judgment, communication skills, the ability to follow the rules and the ability to make and keep friendships
  3. Practical: independence in areas such as personal care, job responsibilities, managing money, recreation and organizing school and work tasks


Conceptual Domain Social Domain Practical Domain
  • In preschool children, there may be no noticeable conceptual differences.
  • For school-age children and adults, there are difficulties in learning academic skills needed to meet age-related expectations.
  • In adults. abstract thinking, executive function (e.g. planning), and short-term memory, as well as functional use of academic skills are impaired.
  • Compared with typically developing age-mates, the individual is immature in social interactions. For example, there may be difficulty in accurately perceiving peers’ social cues. They are often noticed by peers.
  • There may be difficulties regulating emotion and behaviour in an age-appropriate fashion.
  • Individuals need some support with complex daily living tasks in comparison to peers. 
  • In adulthood, supports typically involve grocery shopping, transportation, home and child-care organizing, nutritious food preparation, and banking and money management. 
  • Support is typically needed to raise a family.
  • All through development, the individual’s conceptual skills lag markedly behind those of peers. 
  • Ongoing assistance is needed to complete conceptual tasks of day-to-day life. and others may take over these responsibilities throughout their lifespan.
  • Friendships with typically developing peers are often affected by communication or social limitations. 
  • Significant social and communicative support is needed in work settings for success.
  • The individual can care for personal needs involving eating, dressing, elimination, and hygiene as an adult. 

However, an extended period of teaching and time is needed for the individual to become independent in these areas, and reminders may be needed.

  • Attainment of concepts is limited (e.g., Money, time, quantity). 
  • Caretakers provide extensive supports for problem-solving throughout life.
  • Spoken language is quite limited in terms of vocabulary and grammar.
  • Speech may be single words or phrases, and communication is focused on the here and now within everyday events. 
  • Relationships with family members and familiar others are a source of pleasure.
  • The individual requires support for all activities of daily living, including meats, dressing, bathing, and elimination.
  • The individual always requires supervision. 
  • The individual cannot make responsible decisions regarding the well-being of self or others.
  • Conceptual skills generally involve the physical world rather than symbolic processes. 
  • The individual may use objects in a goal-directed fashion for self-care, work, and recreation. 
  • Motor and sensory impairments may prevent functional use of objects even if certain visuospatial skills are intact (e.g., can match objects based on physical characteristics seen visually but cannot translate to appropriate use).
  • The individual has minimal understanding of speech or gesture. 
  • He or she may understand some simple instructions or gestures and expresses his or her desires and emotions primarily through nonverbal, non-symbolic communication. 
  • The individual enjoys relationships with well-known family members & caretakers primarily.
  • The individual is dependent on others for all aspects of daily living.
  • Although, individuals without severe physical impairments may assist with some daily work tasks at home, like carrying dishes to the table. 
  • Simple actions with objects may be the basis of participation in some vocational activities with high levels of ongoing support.

Causes of ID

Anytime something interferes with normal brain development, intellectual disability can result. However, a specific cause for intellectual disability can only be pinpointed about a third of the time.


The most common causes of intellectual disability are:

  • Genetic conditions. 
  • Problems during pregnancy.
  • Problems during childbirth. 
  • Illness or injury. Infections can lead to intellectual disability.


Treatment for ID

Persons with intellectual disabilities can benefit from therapy and early intervention. Treatment includes the judicious use of medicines, behavioural therapy, and occupational therapy. The treatment plans usually investigate addressing sensory issues, improving communication skills, advising on environmental manipulation, changing maladaptive behaviour, and optimizing functional capabilities.


Those who require child or adult care services may consider inclusive preschools, special student care centres, or centre-based, residential, and home care services. Children with intellectual disabilities can also enrol in either SPED schools or mainstream schools, depending on their individual needs.


Adults with intellectual disabilities can participate in programmes to prepare them for working life. There are training and skills-upgrading programmes to help those with disabilities secure jobs.


What can I do to help my intellectually disabled child?

Steps to help your intellectually disabled child include:

  • Learn everything you can about intellectual disabilities. The more you know, the better advocate you can be for your child.
  • Encourage your child’s independence. Let your child try new things and encourage your child to do things by themselves. Provide guidance when needed and give positive feedback when your child does something well or masters something new.
  • Get your child involved in group activities. Taking an art class or participating in other group activities will help your child build social skills.
  • Stay involved. By keeping in touch with your child’s teachers, you’ll be able to follow their progress and reinforce what your child is learning at school through practice at home.

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