Understanding dementia

Dementia is not a single specific disease, but rather there are many types of dementia with symptoms in common. These are caused by a range of conditions impacting brain function. It is commonly associated with memory loss but can affect speech, cognition, emotional control, behaviour and mobility (WHO 2023). 

Identifying the type of dementia at the time of diagnosis is important to ensure the person receives appropriate treatment and services, and to be better informed about their condition, treatment options and prognosis. However, it is not always straight forward to correctly diagnose the type of dementia based on a person’s symptoms (see How is dementia diagnosed? for more information). If you would like any more information about any of the types of dementia listed in this section, see the Dementia Australia website.

The most common types of dementia include:

  • Alzheimer’s disease – a degenerative brain disease caused by nerve cell death resulting in shrinkage of the brain. 
  • Vascular dementia – mainly caused by haemodynamic (blood flow to the brain) disorders (for example, strokes), thromboembolism (small blood clots that block small blood vessels in the brain), small blood vessel disease in the brain and bleeding into or around the brain.
  • Dementia with Lewy bodies – caused by the degeneration and death of nerve cells in the brain due to the presence of abnormal spherical structures, called Lewy bodies, which develop inside nerve cells.
  • Frontotemporal dementia – caused by progressive damage to the frontal and/or temporal lobes of the brain (Dementia Australia 2022; Draper 2013).

For information on the less common types of dementia, see Less common dementias.

It is common to have multiple types of dementia at once – known as ‘mixed dementia’ – with the most common combination being Alzheimer’s disease and vascular dementia. An increased risk of developing dementia is also linked to the presence of other conditions (such as Parkinson’s disease, Huntington’s disease and Down syndrome), prolonged substance abuse and traumatic brain injuries.

Irrespective of the type of dementia, a person with dementia will experience declining health and ability to live independently. However, the progression of dementia varies considerably from person to person. As the condition progresses, a person with dementia will require increasing care, eventually in all aspects of daily living.

The likelihood of developing dementia increases with age, however, dementia is not an inevitable or normal part of the ageing process. Dementia can also develop in people aged under 65, referred to as ‘younger onset dementia’. There is currently no cure for dementia but there are strategies to manage dementia symptoms that can assist in maintaining independence and quality of life for as long as possible.

Need more information?

If you require more information about dementia, want to know where to seek help if dementia is suspected or want to find out about available support services refer to: