What is intellectual disability?

Communicating with a person with an intellectual impairment

  • Be sure to get the person’s attention by gaining eye contact or respectfully touching their arm.
  • Always assume the person can understand you, then adjust your level of communication according to their response.
  • Communication could include using communication aids or devices, sign language, gestures or facial expressions. You may need to ask whoever is accompanying them to assist you.
  • Use simple, clear words and short, uncomplicated sentences. If the person is an adult, do not speak as though they are a child.
  • Use a respectful tone and volume. Raising the volume of your voice will not help.
  • Don’t rush. Allow the person the time to listen, process your words and respond.
  • Check if they comprehend what you have said by asking them to rephrase in their own words. Do not simply ask, “Do you understand?”
  • If you think they have not understood, try repeating your message more slowly or using different words. It is your responsibility to make sure your message is understood accurately.
  • If you don’t understand the other person, do not pretend to understand. Be honest and say: ‘I’m sorry; I don’t understand what you’re telling me. Would you please tell me again?’
  • If you cannot understand or be understood, try another approach. Is there another way you can communicate what you want to say? Drawing, miming or asking if it’s okay to involve a family member or support worker.

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Intellectual impairment occurs before the age of 18 and is characterised by difficulties in understanding the subtleties of interpersonal interacts. People with this kind of impairment process information more slowly than people without an intellectual impairment. They have difficulty communicating, managing daily living skills, and also have difficulty with abstract concepts such as money and time.

An intellectual impairment may have been caused by problems during pregnancy and birth, health problems or illness, a genetic condition or environmental factors, brain injury or infection, exposure to toxins, substance dependence during pregnancy, or growth and nutrition problems.

Developmental delay

When a child appears to fall behind the development of other children the same age, in one or more areas of their development they may be affected by a developmental delay. They can be delayed in their ability to move, communicate, learn, understand or interact with other children.

Find out more about developmental delay


Autism is a severe behaviour disorder which onsets in early childhood. It is characterised by extreme withdrawal and repetitive stimulation and can significantly affect communication and social interaction. Usually evident by the age of 3 years, it is a neurological disorder that leads to deficits in a child’s ability to communicate, understand language, play, develop social skills and relate to others, which adversely affects their educational performance on into adulthood.

Learn more about Autism

Fragile X syndrome (FXS)

Fragile X is a genetic condition that causes intellectual impairment, behavioural and learning challenges and various physical characteristics. FXS is caused by a mutation in the X chromosome. Though Fragile X occurs in both genders, boys are usually more affected by the syndrome than girls.

Get more information about Fragile X

Down syndrome

A genetic disorder that causes intellectual impairment and physical abnormalities, including short stature and a broad facial profile. It arises from a defect involving a full or partial extra copy of chromosome 21 in their DNA, which can affect their global cognitive ability, and lead to a higher than normal incidence of respiratory and heart conditions.

Visit Down Syndrome Australia for more information

The needs of people with an intellectual impairment

Arbitrary categories of mild, moderate, severe and profound levels of intellectual impairment are defined on the basis of IQ scores. These levels give some guide to the level of support someone might need, but the way the person functions in their life can also depend on other factors such as personality, their circle of support, their coping skills and other disabilities they may have.

They still experience and feel things like joy, anger, pride, hurt, jealousy and other emotions, and want the opportunity to have a range of life experiences. They learn and develop more slowly than average, but can learn to adapt to new situations and enjoy life independently with support.


A mild intellectual impairment is defined as an IQ between 50 and 70. They can integrate and interact with their family and community. They may travel and live independently but require support with money, plans and organising their daily life. They may learn to read and write but it will generally be at a basic level. They may marry and raise children, and have other important relationships in their life, but be awkward or inappropriate in social situations. Subtleties of interpersonal relations and social rules will be difficult for them to understand.


A moderate intellectual impairment is defined as an IQ between 35 and 50. They will have important relationships in life, and will enjoy a range of activities with their family and friends. They may be able to learn to travel on regular public transport with specific guidance, but be unable to problem solve if the bus does not turn up. They may recognise the frame of a word, such as ‘toilet’, ‘exit’, ‘bus stop’, but will have difficulty planning trips and handling money. They can develop independence in personal care and hygiene, but may rely on daily schedules and visual prompts to remember the routine, and will depend on whether or not the person has other disabilities, such as cerebral palsy.


A severe intellectual impairment is defined as an IQ between 20 and 35. A profound intellectual impairment is defined as an IQ below 20. They will usually recognise familiar people, and have a strong relationship with key people in their life. They will most likely have little or no speech, and will rely on non-verbal communication and communication


Our mission is to support people with Intellectual Disabilities to lead meaningful and valued lives. Get in touch with our specialists today for more information on how we can help.

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