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Intellectual disabilities affect someone’s intellectual skills and adaptive behavior, such as the ability to learn, communicate, reason and retain information. Children with an intellectual disability do not learn at the same rate as other children, often reaching developmental milestones later than others, or in some cases, not reaching them at all.

The majority of intellectual disabilities are caused by genetic factors. However, there are other causes of intellectual disabilities, such as brain injury or being born prematurely.

There are many different forms of intellectual disability. Some examples include:

  • Autism
  • Down syndrome
  • Developmental delay



It was reported in 2012 that about 2.9% of the Australian population (2.9 out of 100 people) had an intellectual disability.


Generally, an IQ test is used to diagnose someone with an intellectual disability. However, further medical tests may also be performed, such as genetic testing to aid in determining the cause of the intellectual disability.

If you think that your child is learning at a slower rate than other children or have any worries at all, it is a good idea to visit your local doctor or paediatrician to get them checked early in life for an intellectual disability.

Relevance to section 24 of the NDIS Act

If a diagnosis is made and found the intellectual disability (in accordance with DSM criteria) to be moderate, severe or profound (e.g. having an IQ of less than 55 and adaptive functioning deficits), it is likely that the person will meet the disability requirements in section 24 of the NDIS Act.

Signs and Symptoms

  • Difficulty learning and understanding
  • Difficulty reasoning
  • Displaying a lack of social skills
  • Hyperactivity
  • Slow development (e.g. language development)
  • Lack of adaption to learn from experience
  • Limited functioning of daily activities without assistance



There is no cure for intellectual disabilities. However, there are treatments available to improve the quality of life for people affected by an intellectual disability.

Some treatments include:

  • Special education
  • Behavioral therapy
  • Speech therapy
  • Physical therapy

It is important to note that the earlier the intervention occurs, the better. 

Download: pdfIntellectual Disability Factsheet


This fact sheet provides general information about the disability and is for informational purposes only. It is not a guarantee that you will meet the disability requirements in section 24 of the NDIS Act.

Information sourced from: Achieve AustraliaAAIDDRaising ChildrenABSASHA