Healthdirect Free Australian health advice you can count on.

Medical problem? Call 1800 022 222. If you need urgent medical help, call triple zero immediately

healthdirect Australia is a free service where you can talk to a nurse or doctor who can help you know what to do.

beginning of content

What causes dementia?

2-minute read

Dementia is an umbrella term that describes a collection of symptoms, not one specific disease. There are more than 100 different diseases that cause dementia. The most common are Alzheimer’s disease, vascular dementia and Lewy body disease.

Alzheimer’s disease

Alzheimer’s disease is the most common form of dementia. It is more common in older people than younger people, usually coming on after the age of 65. More than 70% of people with dementia have Alzheimer’s disease.

A few people develop Alzheimer’s disease while much younger. It is likely that these people have inherited Alzheimer’s disease due to problems with one or more of their genes.

People with Alzheimer’s disease have, scattered through their brains, deposits of certain proteins and other material that shouldn’t be there. It is likely that these deposits interfere with the way a person thinks and uses their memory.

Apart from the few cases of familial Alzheimer’s disease (Alzheimer’s that is inherited through a faulty gene), the causes of Alzheimer’s disease are unknown.

Alzheimer’s disease results in a progressive worsening of symptoms over 3 to 20 years.

Vascular dementia

Vascular dementia refers to dementia associated with problems in the circulation of blood to the brain. Some people develop dementia after having lots of small strokes, many of which they would not have even noticed. This is called multi-infarct dementia.

Some people develop dementia because of poor blood flow to the brain, usually due to high blood pressure and thickened arteries. This is called Binswanger's disease or subcortical vascular dementia.

People can also develop dementia after having one large stroke.

Lewy body disease

Lewy body disease is a common form of dementia, similar to Alzheimer’s disease. It is caused by the degeneration and death of nerve cells in the brain. Lewy bodies are unusual round objects that develop within cells in the brain. They probably play a role in killing these cells. It is not clear why they form, nor exactly what they do. It seems they are not inherited.

Frontotemporal dementia

In frontotemporal dementia, the front and/or sides of the brain are affected more than the back of the brain or the central areas. It affects mood, judgement, behaviour and speech.

Frontotemporal dementias begin more often in the 50s and 60s than other types of dementia. They are also more likely to have a genetic element.

Expert advice - is dementia inevitable?

Although dementia is associated with ageing, it is not inevitable. Learn more from an expert about the risk factors of dementia such as ageing, smoking and high cholesterol and blood pressure.

Read the related video transcript

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: October 2018

Back To Top

Need more information?

These trusted information partners have more on this topic.

Top results

Causes of dementia | Dementia Australia

*/ /*-->*/ There is still much to learn about what causes dementia. There are many different types of dementia and the cause varies with type. The information below provides details of some of the major research areas. 

Read more on Dementia Australia website

Dementia: what is it? -

Dementia affects thinking, behaviour and the ability to perform everyday tasks. This article describes some early signs of dementia, who gets dementia and emphasises the importance of a timely medical diagnosis.

Read more on myDr website

Drug treatments & dementia | Dementia Australia

Dementia is the term used to describe the symptoms of a large group of illnesses that cause a progressive decline in a person’s functioning. It is a broad term to describe a loss of memory, intellect, rationality, social skills and what would be considered normal emotional reactions. Dementia causes significant impairment in a person’s day to day functioning.

Read more on Dementia Australia website

Alzheimer's disease -

Alzheimer's disease is the most common form of dementia. Find out all you need to know, including what causes it and whether it can be prevented.

Read more on myDr website

Sleeping | Dementia Australia

Problems with sleeping are a common occurrence for people with dementia. Some people sleep during the day and are awake and restless at night. Some are no longer able to tell the difference between night and day, while others are simply not as active as they used to be and consequently need less sleep.  Causes of sleeping problems It is important to try to recognise what may be causing the problem – is it the environment, the dementia or the medications used? This will help to decide on which strategies may be helpful.

Read more on Dementia Australia website

Delirium and dementia

This Q&A sheet provides information about what delirium is, and, how it relates to people with dementia.

Read more on Dementia Australia website

Lewy Body Disease | Dementia Australia

Lewy body disease is a common form of dementia, sharing many similarities with Alzheimer’s disease. Causes, diagnosis and progression are described here.

Read more on Dementia Australia website

Dementia | SA Health

Dementia affects short-term memory and loss of other mental faculties caused by disease such as Alzheimer’s or strokes. Find a dementia memory clinic.

Read more on SA Health website

Dementia: behavioural and psychological symptoms -

Along with loss of memory and intellectual function, dementia can cause symptoms such as changes in behaviour and mood.

Read more on myDr website

Dementia | Your Health in Mind

Dementia is a medical condition where damage to brain cells causes problems with memory, thinking, behaviour and learnin...

Read more on RANZCP - The Royal Australian and New Zealand College of Psychiatrists website

Healthdirect 24hr 7 days a week hotline

24 hour health advice you can count on

1800 022 222

Government Accredited with over 140 information partners

We are a government-funded service, providing quality, approved health information and advice

Australian Government, health department logo ACT Government logo New South Wales government, health department logo Northen Territory Government logo Government of South Australia, health department logo Tasmanian government logo Government of Western Australia, health department logo