Conditions that can lead to dementia

Dementia isn’t one single disease. Instead, the term ‘dementia’ describes a collection of symptoms caused by disorders affecting the brain. There are over 100 conditions that can lead to the signs and symptoms of dementia. Here are some of the most common.

Alzheimer’s disease

Alzheimer’s disease is the most common form of dementia, estimated to account for at least 60% of dementia diagnoses.

Alzheimer’s disease is a brain disease. Proteins in your brain form plaques and tangles that damage neurons – the cells in your brain that carry messages. These neurons can’t communicate with each other as well as they used to. The neurons eventually die and your brain’s volume shrinks. This damage leads to the symptoms of dementia.

If you have Alzheimer’s disease, you might experience memory loss, slower thinking and changes in your mood, behaviour and perception. These changes can happen in different ways and progress at different speeds for each person.

Alzheimer’s disease is progressive. This means that over time, as the disease develops, your memory, thinking and functioning will become more affected.

There is no known cure for Alzheimer’s disease. But there are treatments that may slow the progress of Alzheimer’s disease and support to help you live the best life you can.

For more information, visit Dementia Australia’s Alzheimer's disease page.

Vascular dementia

Vascular dementia is caused by damage from restricted blood flow in your brain. ‘Vascular’ refers to your blood vessels.

Vascular dementia affects your reasoning, planning, judgement and attention, and how you function. These changes are significant enough to interfere with your daily life.

Often, vascular dementia occurs alongside Alzheimer’s disease or other brain disease, and it can be difficult to diagnose.

There is no known cure for vascular dementia, but medication and treatment can help slow the decline. Support is available.

There are three types of vascular dementia.

Strategic infarct dementia

A single large stroke can sometimes cause vascular dementia, depending on its size and location in the brain. This is known as strategic infarct dementia.

Strategic infarct dementia will cause sudden changes in your thinking skills or behaviour after the stroke. Your exact symptoms will depend on the location of the stroke in your brain.

If you have no further strokes, your symptoms may remain stable or even improve over time. However, if you have more strokes or develop other vascular diseases affecting your brain, your symptoms might get worse.

Multi-infarct dementia

Multi-infarct dementia is caused by multiple strokes. As more strokes happen, more damage is done to the brain.

You might not notice symptoms of multi-infarct dementia when the strokes first occur. But over time, your thinking and functioning will be affected. Depending on the location of the brain damage, you may also experience depression and mood swings.

After each new stroke, your symptoms will worsen and then stabilise for a while.

Subcortical vascular dementia

Subcortical vascular dementia happens when disease in your blood vessels causes damage deep in your brain. Symptoms get worse over time as more damage occurs.

Signs and symptoms of subcortical vascular dementia can include:

· behavioural changes

· trouble controlling your bladder

· reduced ability to plan, problem solve, organise and think logically

· forgetting things, or repeatedly saying the same things

· trouble walking or moving.

For more information, visit Dementia Australia’s vascular dementia page.

Young onset dementia

If you get a diagnosis of any kind of dementia when you’re younger than 65, it’s called young onset dementia, or sometimes early onset dementia.

Young onset dementia isn’t a type of dementia, it just describes how old you were when you got your diagnosis. It’s possible to have young onset Alzheimer’s disease, young onset vascular dementia, and more.

Young onset dementia can have many causes. It’s possible to have one or more conditions that lead to dementia.

In 2025 there are an estimated 29,000 people in Australia living with young onset dementia. This figure is expected to increase to an estimated 41,000 people by 2054.

Because dementia is rarer in younger people, it can often go unnoticed. Noticing early signs and symptoms and talking to your doctor as soon as possible helps.

If you’ve been diagnosed with dementia and you’re younger than 65, you might be eligible for support from the Australian government through the National Disability Insurance Scheme (NDIS).

For more on the NDIS and young onset dementia in general, visit Dementia Australia’s young onset dementia page.

Lewy body dementias

‘Lewy body dementias’ is an umbrella term describing two forms of dementia: dementia with Lewy bodies and Parkinson’s disease dementia.

These two forms of dementia are grouped together because they both involve damage to the brain caused by Lewy bodies.

A Lewy body is a tiny tangle of protein called alpha-synuclein inside brain cells. These tangled proteins cause damage that affects your movement, thinking and behaviour.

Over time, as Lewy body dementia develops, your memory, thinking and behaviour will become more affected.

There’s debate in the medical field about what terms to use in diagnosing people with Lewy body dementias. But you might be given a diagnosis with one of these two terms:

Parkinson’s disease dementia

If you have already been diagnosed with Parkinson’s disease, and at least a year later you start experiencing symptoms of dementia (like changes in your thinking abilities), you will likely be given a diagnosis of Parkinson’s disease dementia.

The progress of Parkinson’s disease dementia can be quite slow compared to other forms of dementia.

Dementia with Lewy bodies

If you have a diagnosis of dementia, and then at least twelve months later you begin to experience symptoms of Parkinson’s disease, you’re likely to receive a diagnosis of Dementia with Lewy bodies.

The most common movement symptoms of Parkinson’s disease are:

• tremors, typically when you’re at rest
• rigidity, or muscle stiffness
• slow movement, which is called bradykinesia
• trouble maintaining your posture and balance.

Symptoms often begin only on one side of your body, then spread to the other over time.

Dementia with Lewy bodies can cause those symptoms, with these differences:

• less tremor, or tremors when you’re at rest or when using your hands
• more stiffness in your torso
• earlier balance problems
• symptoms on both sides of your body.

The progress of dementia with Lewy bodies tends to be faster than the progress of Parkinson’s disease dementia.

Not everyone who has dementia with Lewy bodies will be diagnosed with Parkinson’s disease.

There is no known cure for Lewy body dementia. But there is medication, treatment and support to help you live the best life you can.

For more information, visit Dementia Australia’s page on the Lewy body dementias.

Frontotemporal dementia

Frontotemporal dementia is a brain condition that causes damage to two parts of your brain: the frontal lobe and the temporal lobe.

If you’ve been diagnosed with frontotemporal dementia, you may experience changes in your behaviour, personality, language and movement. Your memory isn’t always affected, especially in the early stages. These changes get worse over time.

Common types of frontotemporal dementia include:

Behavioural-variant frontotemporal dementia

Behavioural-variant frontotemporal dementia is when the brain’s frontal lobes are affected first. You’ll experience changes in your personality and behaviour as the areas of your brain that control conduct, judgement, empathy and foresight become damaged.

Primary progressive aphasia

Primary progressive aphasia is when the temporal lobes are affected first. You’ll experience a loss of language skills. Other aspects of thinking, perception and behaviour are not affected as much in the early stages.

There are three types of primary progressive aphasia:

Progressive non-fluent aphasia

Progressive non-fluent aphasia is when you develop problems speaking and, over time, lose your ability to speak fluently.

Semantic dementia

Semantic dementia is when you lose your ability to assign meaning to words, think of the right word, or name people and objects. You may also experience changes in your behaviour, like becoming obsessed with routines and emotional responses.

Reading, spelling, comprehension and expression aren’t usually affected. You might also keep decision-making or motor skills. You can usually do daily activities until very late in the condition.

Logopenic aphasia

Logopenic aphasia is when you keep your knowledge of what words mean, but have increasing trouble thinking of the right word to say. Because of this, it might take you a long time to say things.

You might also struggle to repeat things you or someone else just said. Long sentences might become harder to read.

There’s no known cure for frontotemporal dementia yet. But treatment can help with some symptoms, and support is available.

For more information, visit Dementia Australia’s frontotemporal dementia page.

Alcohol-related brain injury (ARBI)

Alcohol-related brain injury (ARBI) is damage to the brain caused by consuming alcohol at risky levels for many years.

ARBI causes damage to your brain. It can affect your memory, learning, thinking, personality, mood and social skills.

The longer and more regularly someone consumes risky levels of alcohol, the more likely they are to develop ARBI. However, if you get treatment early and stop drinking alcohol, you can slow the damage and stop more damage happening. You may be able to recover at least some of the losses.

Alcohol-related brain injury (ARBI) is also often linked with:

Wernicke’s encephalopathy

Wernicke’s encephalopathy is an intense swelling of your brain caused by a severe lack of thiamine. It usually develops suddenly.

Someone with Wernicke’s encephalopathy may experience:

• jerky eye movements, double vision and trouble moving muscles
• loss of muscle coordination, poor balance, staggering or inability to walk
• confusion or memory problems
• signs of malnutrition, including unplanned weight loss, tiredness, weakness and vitamin deficiency.

The symptoms of Wernicke’s encephalopathy can be different from person to person. If you’re concerned about yourself or someone else, talk to your doctor.

If it isn’t treated, Wernicke’s encephalopathy can cause permanent brain damage and lead to Korsakoff’s syndrome.

Korsakoff’s syndrome

Korsakoff’s syndrome is caused by damage deep in your brain that affects your ability to:

• form new memories
• learn new things.

Korsakoff’s syndrome often develops if you don’t get treatment for Wernicke’s encephalopathy. But it can also develop on its own if you use alcohol at risky levels over time. Korsakoff’s syndrome usually develops gradually.

Someone with Korsakoff’s syndrome may experience:

• trouble forming new memories and learning new things
• more rarely, loss of older memories
• personality changes
• making up stories to fill gaps in memory (confabulation)
• seeing or hearing things that aren’t there (hallucinations)
• not understanding or not believing you have Korsakoff’s syndrome.

If you have Korsakoff’s syndrome, what happens next depends on:

• how soon you get treatment
• how much brain damage you already have.

If you experience both Wernicke’s encephalopathy and Korsakoff’s syndrome at once, it’s called Wernicke-Korsakoff Syndrome (WKS).

Support is available if you want to stop drinking alcohol, or have alcohol-related brain injury. For more information, visit Dementia Australia’s Alcohol-related brain injury (ARBI) page.

Human immunodeficiency virus (HIV)-associated dementia

HIV-associated dementia is a brain condition linked to the Human Immunodeficiency Virus (HIV).

HIV attacks the body’s immune system and can lead to Acquired Immune Deficiency Syndrome (AIDS).

Some people with HIV/AIDS develop dementia symptoms. HIV-associated dementia affects your thinking, movement and behaviour. You might lose independence and quality of life.

Not everyone who has HIV/AIDS will develop HIV-associated dementia. In Australia, HIV-associated dementia is not common, but about a third of people with HIV/AIDS will develop a milder form of neurocognitive (brain and thinking) condition.

For more information, visit Dementia Australia’s human immunodeficiency virus (HIV)-associated dementia page.

Chronic traumatic encephalopathy (CTE)

Chronic traumatic encephalopathy (CTE) is a neurological condition believed to result from repeated head trauma over time. These injuries can damage brain tissue, affecting your memory, thinking, mood, and behaviour.

CTE can only be definitively diagnosed after death through neuropathological examination.

During life, a medical specialist may diagnose you with suspected CTE (called ‘traumatic encephalopathy syndrome’), based on:

• clinical history
• symptoms
• exclusion of other conditions.

Multiple concussions increase the risk of CTE, but even repeated head impacts that do not cause noticeable concussion symptoms can contribute to brain changes.

There is no known cure for CTE. Early identification, symptom management, and access to therapeutic supports can help people live well.

For more information, visit Dementia Australia’s chronic traumatic encephalopathy (CTE) page.

Blast-induced traumatic brain injury (BiTBI)

Blast-induced traumatic brain injury (BiTBI) is caused by repeated rapid overpressure exposure from explosions, such as those experienced in military training, combat, or exposure to controlled detonations. These pressure waves can damage brain tissue in ways that are different from repetitive concussive or sub-concussive impacts.

While some individuals with BiTBI may have symptoms similar to CTE, the underlying injury mechanisms and neuropathology are different. Recognising this distinction ensures appropriate care and support.

Most exposures now occur during routine training rather than combat, across a range of conventional and civilian settings, not just in military special operations.

Under the Australian Veterans’ Covenant, any person who has served in the Permanent Forces or Reserves, even for a single day, is recognised as a veteran. This reinforces the importance of appropriate assessment, recognition, and support pathways.

For more information, visit Dementia Australia’s blast-induced traumatic brain injury (BiTBI) page.

Childhood dementia

Dementia is usually associated with adults. But young children and teenagers can develop dementia too.

Childhood dementia is a brain condition that affects memory, behaviour, emotions and communication.

Childhood dementia can be caused by more than 100 rare genetic disorders. These include Niemann-Pick type-C, Batten disease and Sanfilippo syndrome. Children experiencing childhood dementia are born with these disorders.

Each child’s experience with dementia is unique. Unfortunately, there is no known cure for childhood dementia, and like other forms of dementia, it is progressive. Unfortunately, half of all children with dementia lose their lives by the age of 10.

For more information, visit Dementia Australia’s childhood dementia page.

Down syndrome

If you have Down syndrome, you are more likely to develop Alzheimer’s disease, and at a younger age. People with Down syndrome make 1.5 times as much of a substance called amyloid precursor protein as other people. This seems to cause earlier Alzheimer’s disease symptoms in people with Down’s syndrome.

Not everyone with Down syndrome develops dementia. Around half of all people with Down syndrome will develop Alzheimer’s disease by age 60. The average age when symptoms start is the early to mid-50s.

By age 40, almost all people with Down syndrome have changes in their brains associated with Alzheimer’s disease. You may not have symptoms of Alzheimer’s at this age, but they can develop in the future.

However, some people with Down syndrome who are over 40 show no signs of Alzheimer’s disease. We don’t yet know exactly why this happens.

There is no known cure for Alzheimer’s disease. But there is support to help you live your best possible life.

For more information, visit Dementia Australia’s Down syndrome and Alzheimer’s disease page.

Posterior cortical atrophy (PCA)

Posterior cortical atrophy (PCA) involves the loss and dysfunction of brain cells, particularly at the posterior (back) of the brain.

If you have PCA, the tissue in the outer layer of your brain will shrink as you lose cells.

This loss of brain tissue can lead to problems with vision, spelling, writing and arithmetic.

People often start experiencing PCA symptoms in their 50s or 60s. It can also affect older people.

For more information, visit Dementia Australia’s posterior cortical atrophy (PCA) page.

Limbic-predominant age-related TDP-43 encephalopathy (LATE)

Limbic-predominant age-related TDP-43 encephalopathy (LATE) is a recently defined cause of dementia. Similar to other forms of dementia, such as Alzheimer’s disease, it causes problems with memory and thinking but has different underlying causes.

Dementia is the result of changes in the brain that cause nerve cells (neurons) to stop working properly. For example, brain changes associated with Alzheimer’s disease are caused by the buildup of amyloid plaques and tau proteins.

On its own, LATE has a slower rate of clinical change than Alzheimer's disease. More than 3,000 donors examined with LATE, also showed evidence of Alzheimer’s disease. This suggests that having more than one of these brain disorders may contribute to more rapid decline than either disease alone.

For more information, visit Dementia Australia’s limbic-predominant age-related TDP-43 encephalopathy (LATE) page.

Other causes of dementia

Other conditions that can lead to the signs and symptoms of dementia include:

• Huntington's disease
• prion diseases, including Creutzfeldt-Jakob disease (CJD)
• normal pressure hydrocephalus (NPH)
• multiple system atrophy
• Multiple sclerosis-related dementia (MSRD)
• leukoencephalopathies
• progressive supranuclear palsy
• corticobasal degeneration.

Dementia Australia support

When I was diagnosed with Alzheimer’s (disease) I had never been so scared in my life […] I am happy to say that I have received amazing support from my family, medical team and Dementia Australia.

- Linda, living with young onset Alzheimer’s disease

Whatever your experience of dementia, we're here for you. You can contact the National Dementia Helpline any time of the day or night for information, advice and support.

Where to get help (key organisations with web links and phone numbers):

• Your GP
• The National Dementia Helpline, 1800 100 500
• NDIS: the National Disability Insurance Scheme: available if you’re diagnosed with dementia when you’re under 65.
• My aged care: support in navigating decisions around aged care.
• Carer Gateway: emotional and practical services for carers.
• Dementia Behaviour Management Advisory Service (DBMAS): 24/7 advice for people caring for someone with dementia.