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What is intellectual disability?

Two people smiling and supporting each other.

Intellectual disability is a lifelong condition that affects a person’s intellectual skills and their behaviour in different situations.  

It can include difficulties in communication, memory, understanding, problem solving, self-care, social and emotional skills and physical skills.   

People with intellectual disability have the same feelings, rights, and aspirations as everyone else.  

Intellectual disability does not define who a person is, how they should be treated or how they want to live. 

What causes intellectual disability? 

A person can be born with an intellectual disability or acquire it before age 18.  

Some of the most common causes of intellectual disability include: 

Click on the links to find out more about these conditions. 

Many people with an intellectual disability also experience other types of disability, such as a speech, hearing or physical disability, autism or a mental health condition. 

How is intellectual disability diagnosed?  

Intellectual disability can be diagnosed in children (under 18) by a clinical psychologist or psychiatrist.

It is diagnosed using:  

  • an IQ test
  • an adaptive behaviour test.  

It is usually diagnosed in early childhood and may be suspected if a child is developing slower than other children.  

A diagnosis can help people access government services like the NDIS and the Disability Support Pension.  

For example, people with an IQ of less than 70 are automatically eligible for the Disability Support Pension. 

Sometimes intellectual disability goes undiagnosed in childhood. This can be a barrier to people accessing the services and supports they need.  

More information on diagnosing intellectual disability can be found on the American Psychiatric Association website.

What support do people with intellectual disability need? 

Every person with an intellectual disability is different.  

Some people live independently with support from family, friends or paid supports, while other people may need help with many aspects of their lives. 

Some areas of support might include: 

  • Organising daily life activities 
  • Communication 
  • Social interaction 
  • Problem solving 
  • Self-care 
  • Reading and writing 
  • Using money 
  • Administrative processes, like government systems. 

With the right support, all people with an intellectual disability can learn and develop new skills. 

Language, then and now 

Over the past 40 years, there has been a big shift in the way we think and talk about disability.  

Even our early names included old-fashioned words that were not respectful. Now we use rights-based and person-first language when we talk about disability. 

In the past, many terms used to describe intellectual disability were not respectful.  

Most commonly we use the term “person with an intellectual disability” although some people also prefer the term “disabled person”. 

Learn about the history of Inclusion Australia.

The social model of disability  

We now understand that disabling barriers presented by society impact heavily on peoples’ lives.  

It is these social barriers, not just peoples’ individual impairments, which create disability.  

This is called the social model of disability.  

The United Nations Convention on the Rights of Persons with Disabilities (CRPD) is based on the social model of disability. 

It enshrines universal rights for all people with disabilities.  

Learn more about our work to promote human rights for people with intellectual disabilities.

The voices of people with an intellectual disability 

The CRPD was driven by and continues to support disability rights movements all over the world, including Australia.  

Unfortunately, across the world, the voices of people with intellectual disability have been excluded, even from disability rights movements.

In Australia too, the diverse rights and needs of different groups of people with intellectual disability are often overlooked. 

This is particularly the case for people with higher and more complex support needs.  

Learn how we increase the voice of people with intellectual disability.

“We challenge all those who would define intellectual disability as simply slower or deficient ways of remembering, thinking and communicating.

Our message is clear. Respect and understand differences. Value all people for their contributions.

Treat all people with equality regardless of their disability, religious, gender, ethno-racialcultural, sexual orientation, and other differences.”

– Inclusion International