What dementia is
The World Health Organization defines dementia as a syndrome that leads to a decline in the ability to process thought, beyond what is expected from the usual consequences of ageing.
Dementia can affect a person’s:
- memory
- thinking
- behaviour
- communication
- judgement
- ability to perform daily activities.
Who can be affected
Dementia can affect anyone of any age; however, it is most common among people aged 65 years and older. While ageing increases your risk of dementia, it is not a normal part of ageing.
Younger onset dementia describes any form of dementia affecting a person under the age of 65.
Children can also experience dementia resulting from progressive brain damage caused by over 100 rare genetic disorders.
Types of dementia
There are multiple types of dementia, including:
- Alzheimer’s disease
- vascular dementia
- dementia with Lewy bodies
- frontotemporal dementia
- alcohol-related dementia
- younger onset dementia
- chronic traumatic encephalopathy (CTE).
You can learn more about the different types of dementia on the Dementia Australia website.
Reduce your risk of dementia
Looking after your brain and body throughout your life can help you reduce your risk of developing dementia. It is never too early or too late to take action and improve your brain health.
Some types of dementia are due to factors that cannot be changed like genetics and family history.
But there are things you can do through your life that may help you reduce your risk of dementia. Globally, it is estimated that 45% of dementia cases could be delayed or avoided by addressing these risk factors where possible (Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission):
- Stay physically active
- Stop smoking
- Reduce alcohol consumption
- Lower high LDL cholesterol
- Protect your head from injury
- Keep socially connected
- Keep mentally stimulated
- Seek treatment for depression
- Maintain a healthy weight
- Manage high blood pressure
- Protect your hearing.
- Protect your vision.
- Reduce exposure to air pollution.
The most preventable form of dementia is vascular dementia. This type of dementia can be prevented by minimising risk factors for stroke and other conditions that damage blood vessels and reduce circulation.
For more information on dementia risk factors and how to lower your risk of dementia, visit the Dementia Australia website or read the Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission.
To learn more about the wider determinants of health, including risk factors for dementia, see the National Preventive Health Strategy.
Dementia in Australia
The Australian Institute of Health and Welfare estimates that in 2025 there are 433,000 Australians living with dementia. This number is projected to almost double by 2058.
In 2023, dementia was the second leading cause of death in Australia, and the leading cause of death among Australian women.
In Australia:
- 1 in 12 people aged 65 and over are living with dementia
- 2 in 5 people aged 90 and over are living with dementia
- Dementia prevalence rates are 3 to 5 times higher among Indigenous Australians.
For reports and statistics about dementia in Australia, see the Australian Institute of Health and Welfare.