What is intellectual disability

What is an intellectual disability?

An intellectual disability affects how a person learns, solves problems and manages daily activities. It is usually identified before the age of 18 and stays with a person throughout their life.

People with an intellectual disability may take longer to learn new things. They might find it harder to communicate, manage money, understand time or look after themselves without some help.

In Australia, intellectual disability is one of the most common types of disability. Around 3% of Australians have an intellectual disability, with more than half a million people affected.¹ ²

An intellectual disability can be caused by:

• Genetic conditions
• Problems during pregnancy or birth
• Illness or health problems in early childhood
• Environmental factors such as exposure to toxins

Everyone with an intellectual disability is different. The level of support someone needs varies from person to person. With the right support, people with intellectual disabilities can learn new skills, work, build relationships and live independently.

Types of intellectual disabilities

Below are some examples of intellectual disabilities. Each person’s experience is unique, and many people live fulfilling lives with appropriate support.

Fragile X syndrome

Fragile X syndrome is the most common inherited cause of intellectual disability worldwide. It is a genetic condition caused by a change in the FMR1 gene on the X chromosome.

People with Fragile X syndrome may experience a wide range of physical, developmental, behavioural and emotional differences. The effects vary greatly from person to person.

Common characteristics can include developmental delays, learning differences, communication difficulties, anxiety, ADHD, and traits similar to autism such as difficulty with social interactions and sensory processing.

Fragile X syndrome affects around 1 in 4,000 males and 1 in 6,000 females in Australia.⁴ ⁵ It is estimated that about 90,000 Australians are affected by Fragile X in some way, either as carriers or with the syndrome itself.⁴

Down syndrome

Down syndrome is a genetic condition, not a disease or illness. It occurs when someone is born with a full or partial extra copy of chromosome 21.

Down syndrome is the most common chromosomal condition. In Australia, around 265 babies are born with Down syndrome each year, which is approximately 1 in every 1,150 births.³ There are an estimated 13,000 to 15,000 people living with Down syndrome in Australia.³

People with Down syndrome may have some common physical characteristics and a higher chance of certain health conditions, including heart and respiratory issues. Many people also have some level of intellectual disability, though this varies greatly between individuals.

With the right support, people with Down syndrome attend school, work, build relationships and contribute to their communities in meaningful ways.

Find out more:

Myths about Down syndrome

Growing up with down syndrome

Developmental delay

Developmental delay describes when a child develops skills more slowly than other children of the same age.

One or more areas of development may be affected, including movement, communication, learning, understanding and social skills.

Some children with developmental delay catch up as they grow. For others, the delay may continue and affect their learning and daily life into adulthood.

Early intervention and support can make a significant difference in helping children reach their potential.

Prader-Willi syndrome

Prader-Willi syndrome is a rare genetic condition caused by a change in the genes on chromosome 15. It affects around 1 in 10,000 to 20,000 people.⁶

One of the most recognised characteristics is a constant feeling of hunger, which usually begins around age two. This happens because the brain does not receive signals that the stomach is full.

Other characteristics can include low muscle tone, shorter stature, and some level of intellectual disability. Children may find language, problem-solving and maths more challenging.

With the right support, including help with managing food and nutrition, people with Prader-Willi syndrome can lead fulfilling lives.

Find out more:

Myths about Prader-Willi syndrome

Kate’s story about living with Prader-Willi syndrome

Fetal alcohol spectrum disorder (FASD)

FASD describes a range of conditions caused when a baby is exposed to alcohol during pregnancy. Alcohol crosses the placenta and can affect the developing baby.

FASD is more common than many people realise. Recent research suggests that around 2 to 4% of Australians may have FASD, making it one of the leading preventable causes of intellectual disability.⁷ ⁸

The effects of FASD can vary and may include learning difficulties, memory and attention problems, behavioural challenges, and difficulty with social skills. Some people may also have distinctive facial features or physical differences.

FASD is often misdiagnosed as autism or ADHD due to similar characteristics. Early diagnosis and support can help people with FASD thrive.

The National Health and Medical Research Council recommends that women who are pregnant or planning a pregnancy avoid alcohol altogether, as there is no known safe level of drinking during pregnancy.⁹

Other causes of intellectual disability

Sometimes an intellectual disability is caused by environmental factors or other circumstances. These can include:

• Complications during pregnancy, such as infections
• Difficulties during birth
• Exposure to toxins like lead or mercury
• Illnesses such as meningitis, measles or whooping cough
• Significant malnutrition in early childhood
• Trauma or injury to the brain
• Unknown causes

In many cases, the exact cause of an intellectual disability may not be identified. What matters most is providing the right support for each person to live their best life.

How Aruma supports people with intellectual disabilities

At Aruma, we support people with intellectual disabilities to live the life they choose. We believe everyone deserves the chance to learn, grow and achieve their goals.

Our approach is guided by The Aruma Way, our quality framework built on four promises:

• Your Way – Person-centred support that puts you at the centre of every decision
• The Safe Way – Keeping everyone safe from harm
• The Right Way – Effective support provided the way it should be
• Together – Working in partnership with you, your family and your support network

Whether you need help with daily living, therapy services, employment support or finding the right home, we are here to help.

References

All statistics and information on this page have been sourced from the following organisations:

1. _{Australian Institute of Health and Welfare (AIHW) – Disability in Australia: Intellectual Disability https://www.aihw.gov.au/reports/disability/intellectual-disability-australia/summary}
2. _{Australian Institute of Health and Welfare (AIHW) – People with Disability in Australia 2024 https://www.aihw.gov.au/reports/disability/people-with-disability-in-australia/contents/summary}
3. _{Down Syndrome Australia – Population Statistics https://www.downsyndrome.org.au/about-down-syndrome/statistics/}
4. _{Fragile X Association of Australia – Understanding Fragile X https://www.fragilex.org.au/understanding-fragile-x/}
5. _{Better Health Channel (Victoria) – Fragile X Syndrome https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/fragile-x-syndrome}
6. _{Better Health Channel (Victoria) – Prader-Willi Syndrome https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/prader-willi-syndrome}
7. _{Better Health Channel (Victoria) – Fetal Alcohol Spectrum Disorder (FASD) https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/fetal-alcohol-spectrum-disorder-fasd}
8. _{University of Sydney / Drug and Alcohol Review (2025) – Estimating the Prevalence of Fetal Alcohol Spectrum Disorder in Australia https://pmc.ncbi.nlm.nih.gov/articles/PMC12228015/}
9. _{National Health and Medical Research Council – Australian Guidelines to Reduce Health Risks from Drinking Alcohol https://www.nhmrc.gov.au/about-us/publications/australian-guidelines-reduce-health-risks-drinking-alcohol}
10. _{Murdoch Children’s Research Institute – Fragile X Syndrome https://www.mcri.edu.au/impact/a-z-child-adolescent-health/d-f/fragile-x-syndrome}