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Intellectual disability

Summary

A person with an intellectual disability may have difficulty learning and managing daily living skills. This is due to impaired cognitive (thought-related) processing before the age of 18 years, resulting in an IQ below 70. However, everyone is unique. How a person functions in their daily life depends on many factors, not just their IQ level.

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Around two to three percent of Australians have an intellectual disability. Having an intellectual disability means that the person finds it more difficult to learn and process new information, and to manage the complex tasks required for every day living.

Intellectual disability is not a psychiatric or mental health problem. A person is said to have an intellectual disability if, by the age of 18, they have three indications being:

  • significant difficulty with intellectual functions such as reasoning, problem solving and academic learning
  • an IQ below 70, with clinical judgement required to interpret the IQ test
  • significant difficulty with daily living skills, including looking after themselves, communicating and taking part in activities with others.
Intellectual disability affects some people more than others. Of the approximately 500,000 Australians who have an intellectual disability, most (approximately 85%) have a mild intellectual disability and many never seek or receive disability services.

For those who require help and support, there is a range of services available to help them achieve and maintain optimal independence, health and wellbeing.

Characteristics of people with an intellectual disability


Every person is unique, with their own personality and areas of ability and areas of difficulty. Generally, a person with an intellectual disability:
  • learns and processes information more slowly than people without an intellectual disability
  • has difficulty with abstract concepts, such as money and time
  • has difficulty understanding the subtleties of interpersonal interactions.

Causes of intellectual disability


There are many causes of differences in brain development that can cause intellectual disability. A specific cause can be identified in approximately two thirds of cases. Known causes include:
  • genetic causes – differences in genes and chromosomes
  • trauma to the developing brain either before, during or after birth (including accident, injury and abuse)
  • infection in the brain before during or after birth
  • toxins or poisons injuring the developing brain, including alcohol and some medication
  • nutritional deficiencies
  • metabolic diseases.

Risk factors for intellectual disability


The risk of intellectual disability is higher when:
  • babies are born before their expected birth date (extreme prematurity
  • there are serious health problems during childhood
  • the mother takes drugs, including alcohol and smoking, during pregnancy
  • there is severe environmental deprivation
  • there is a strong family history of intellectual disability in other family members.

Prevention of intellectual disability


It is possible to minimise the number of people affected by intellectual disability through:
  • universal immunisation, including rubella vaccination for girls and women
  • women taking folic acid supplements before and during pregnancy to prevent neural tube defects
  • avoiding alcohol, nicotine or illicit drugs during pregnancy
  • genetic counselling and prenatal screening
  • early detection of ‘high-risk’ pregnancies
  • screening tests for newborn babies
  • regular visits to maternal and child health services
  • using child safety strategies and equipment to prevent injury – such as pool fencing, safe storage of toxins, car seats and capsules, bike helmets
  • improving nutrition
  • avoiding exposure to harmful chemicals
  • early detection and prompt treatment of health problems and childhood illness
  • providing an enriching and stimulating environment for children
  • identifying special educational needs of children.

Needs of people with an intellectual disability


The level of intellectual disability is defined on the basis of adaptive functioning which, in turn, determines the level of supports someone may require. Categories of mild, moderate, severe and profound levels of intellectual disability are defined.

However, the way the person functions in their life also depends on other factors, including:
  • their personality
  • their coping skills
  • other disabilities – for example, physical, social or sensory
  • the amount of support provided by family, friends and the community
  • what is demanded of them in different situations – for example, at home or at work.
People with a mild intellectual disability will generally be able to;
  • participate in and contribute to their family and their community
  • have important relationships in their life and may marry and raise children with the support of family, friends and support services
  • live and travel independently, but may need support and help to handle money, and to plan and organise their daily life
  • work (either with or without some level of support)
  • learn to read and write, with appropriate teaching. People who have an intellectual disability are likely to have difficulty with academic learning, and their reading and writing may be at a basic level. Some people may not have had the educational support they needed to learn to read or write, and they may be self-conscious about this. It is important to be sensitive when asking people to read information or complete written forms
  • find the subtleties of interpersonal relationships and social rules difficult to fully understand. They may therefore sometimes behave awkwardly or inappropriately in social situations.
People with a moderate intellectual disability will generally:
  • have important relationships in their life and will probably form valued and lasting friendships
  • enjoy a range of activities with their family, friends and acquaintances
  • be able to learn to travel on regular public transport routes with specific training, but will have difficulty planning trips and handling money. They may have difficulty problem solving when unexpected events occur
  • learn to recognise some words in context, such as common signs including ‘Ladies’, ‘Gents’ and ‘Exit’
  • be able to make choices and understand daily schedules or future events, if provided with visual prompts such as daily timetables and pictures of planned events
  • need lifelong support in planning and organising their life and activities
  • develop independence in personal care, such as toilet hygiene, dressing and bathing. The extent to which this occurs will depend on opportunities to learn and practise these tasks, and whether or not the person has other disabilities, such as cerebral palsy.
People with a severe or profound intellectual disability will generally:
  • recognise familiar people and may have strong relationships with key people in their life
  • have little or no speech, and will rely on gestures, facial expression and body language to communicate needs or feelings. Communication systems for people with this level of disability generally rely on photographs or objects to support understanding. For example, you might use a cup or a photograph of a cup with the spoken question: ‘Would you like a drink?’
  • require lifelong help with personal care tasks, communication, and accessing and participating in community facilities, services and activities.

Tips for communicating with a person with an intellectual disability

  • Make sure you have the person’s attention. Use their name, gain eye contact or respectfully touch their arm.
  • Start by assuming a person can understand you, and then adjust your level of communication according to their response.
  • Ask the person how they would like to communicate if they do not use speech. This could include using communication aids or devices, answering with a way of saying ‘yes’ or ‘no’ to questions (for example, using eye gaze, or head or hand movements), sign language, gestures or facial expressions. If you are not able to understand the person, you may need to ask whoever is accompanying them to help you.
  • Use visual information such as pictures, diagrams, signs, objects, gestures or miming to improve understanding.
  • Use appropriate language for the person and the situation – for example, 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. If the person does not understand you, try a different way of providing the information or asking the question – don’t assume that raising the volume of your voice will help.
  • Don’t rush. Allow the person the time to listen, process your words and respond. Waiting patiently conveys interest in and respect for what they will say.
  • Check if you have communicated clearly. Perhaps ask the person you are speaking with, to repeat what you have said in their own words. Do not simply ask, ‘Do you understand?’ because people will often say ‘yes’ to avoid embarrassment or because it is the answer they think you want to hear. If you think you have not been 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. Be honest and take responsibility for any communication breakdowns. For example, say, ‘I’m sorry; I don’t understand what you’re telling me. Would you please tell me again?’ If you still cannot understand, try another approach. Is there another way you can communicate what you want to say? Ask if it’s okay to involve someone who is familiar to the person (a family member or support worker).

Independent living for people with an intellectual disability


People with intellectual disability:
  • experience and feel the same emotions as everyone else, including joy, anger, pride, hurt, jealousy, loss and grief
  • want the opportunity to have a range of life experiences
  • learn and develop more slowly, but can learn to adapt to new situations and enjoy life independently.

The power of language


The language we use reflects our own knowledge and attitudes, and affects those of others. The correct terminology is to describe the person first, and then the disability. For example, Sally is a young woman with an intellectual disability. John is an elderly man with cerebral palsy and an intellectual disability.

Expressions such as ‘mentally retarded’ or ‘mentally handicapped’ are outdated, misleading and offensive. Using terms like these can lead to community ignorance, which further isolates people with intellectual disabilities.

Services for people with an intellectual disability


There are a range of state and federally funded services for people with intellectual disability. The services and funding will change as the National Disability Insurance Scheme is rolled out across the nation. In Victoria, the state government Department of Human Services will continue to coordinate and provide services until the National Disability Insurance Scheme is operating throughout the State.

Services available through the Victorian Department of Human Services include:
  • family and individual support
  • in-home support
  • respite and accommodation
  • community support and employment
  • aids and equipment
  • behaviour support.

Where to get help

  • Your doctor
  • Maternal and child health service
  • Local community health centre
  • Your local council
  • Disability Intake and Response Service Tel. 1800 783 783, TTY 1800 008 149
  • Your Department of Human Services regional office
  • www.dhs.vic.gov.au/for-individuals/disability
  • Centre for Developmental Disability Health Victoria Tel. (03) 9902 4467
  • Scope Tel. (03) 9843 3000
  • Yooralla Community Learning and Living Centre Tel. (03)9666 4500, TTY (03) 9916 5899

Things to remember

  • People with intellectual disabilities have the same range of desires, needs, emotions and dreams as the rest of the population.
  • Show respect for the person and communicate in ways that acknowledge their abilities, their age, the value of their contribution.
  • Use appropriate respectful language when speaking to or about people with intellectual disability. Terms like ‘mental retardation’ are outdated and offensive.
  • People with an intellectual disability may learn more slowly, but can adapt to new situations and enjoy usual life experiences.
  • There are many resources available in the community to help people with intellectual disabilities to lead independent lives.
  • Categories of mild, moderate, severe and profound levels of intellectual disability are defined on the basis of significant difficulty with intellectual functions and daily living skills.
  • Factors such as personality, presence of other disabilities and social support also play important roles in how the person functions in their daily life.

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This page has been produced in consultation with and approved by:

Centre for Developmental Disability Health Victoria

(Logo links to further information)


Centre for Developmental Disability Health Victoria

Last reviewed: October 2014

Content on this website is provided for education and information purposes only. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your doctor or other registered health professional. Content has been prepared for Victorian residents and wider Australian audiences, and was accurate at the time of publication. Readers should note that, over time, currency and completeness of the information may change. All users are urged to always seek advice from a registered health care professional for diagnosis and answers to their medical questions.


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A person with an intellectual disability may have difficulty learning and managing daily living skills. This is due to impaired cognitive (thought-related) processing before the age of 18 years, resulting in an IQ below 70. However, everyone is unique. How a person functions in their daily life depends on many factors, not just their IQ level.



Content on this website is provided for education and information purposes only. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your qualified health professional. Content has been prepared for Victorian residence and wider Australian audiences, and was accurate at the time of publication. Readers should note that over time currency and completeness of the information may change. All users are urged to always seek advice from a qualified health care professional for diagnosis and answers to their medical questions.

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