Alzheimer's disease

When I received my diagnosis, I was advised to move on with my life and do everything on my wish list […] but I wanted to understand the how, what and why of dementia. 

Robyn, living with Alzheimer’s disease

About Alzheimer’s disease

Alzheimer’s disease is the most common form of dementia. 

Alzheimer’s disease is 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.

Are Alzheimer's disease and dementia the same thing?

Alzheimer's disease is one form of dementia, the most common form. But many other conditions can also lead to dementia.

Dementia is a term that describes a collection of symptoms caused by disorders affecting the brain.

For more on dementia, visit our introduction to dementia page:

Causes of Alzheimer’s disease

The causes of Alzheimer’s disease are complex and not fully understood. But there are two changes in the brain that are believed to cause damage that leads to the symptoms of Alzheimer’s disease. They are called plaques and tangles.

Beta amyloid plaques and Alzheimer’s disease

There is a protein in your brain called beta amyloid (Aβ). Proteins are long molecules that are folded into specific shapes. When beta amyloid proteins fold the wrong way, they clump together and form plaques.

Just like plaque sticks to your teeth, plaques of beta amyloid proteins stick to the outside of cells in your brain, damaging them. This damage leads to the symptoms of Alzheimer’s disease.

Tau protein tangles and Alzheimer’s disease

Another protein in your brain is called tau. When some forms of tau protein fold the wrong way, they tangle up together. These bundles of tangled protein are also called neurofibrillary tangles.

Tangles of tau proteins inside brain cells cause damage. This damage leads to the symptoms of Alzheimer’s disease.

There’s a lot of evidence that plaques and tangles are causes of Alzheimer’s disease, but they don’t explain all cases. Researchers are investigating what other causes of Alzheimer’s disease might exist.

Genetics and Alzheimer’s disease

The most important known gene affecting your risk of developing Alzheimer’s disease is called Apolipoprotein E. It has three types: type 2, type 3 and type 4.

Every person has two Apolipoprotein genes. You can have two of the same type or two different types. If you have at least one type 4, known as ApoE ε4, and especially if you have two type 4s, you are at higher risk of developing Alzheimer’s disease than people with other types.

But the risk isn’t that much higher: half of all people aged 85 who have two copies of ApoE ε4 don’t have symptoms of Alzheimer’s disease.

ApoE ε4 has also been associated with increased risk for cardiovascular disease and vascular dementia. 

For more on the way genes affect dementia risk, visit our genetics and dementia page:

Types of Alzheimer’s disease

Sporadic Alzheimer’s disease

Sporadic Alzheimer’s disease is by far the most common form of Alzheimer’s disease. Around 95% of people who living with Alzheimer’s disease have sporadic Alzheimer’s disease.

People living with sporadic Alzheimer’s disease generally don’t have a family history of Alzheimer’s disease and tend to develop it when they’re older.

Familial Alzheimer’s disease

A very small number of people inherit Alzheimer’s disease from their biological parents. People with familial Alzheimer’s disease often start getting symptoms in their 50s, sometimes younger.

If you’re diagnosed with any form of Alzheimer’s disease when you’re younger than 65, it’s called younger onset Alzheimer’s disease. 

For more information, advice and support on younger onset Alzheimer’s disease, visit our younger onset dementia page:

Down syndrome and Alzheimer’s disease

People with Down syndrome have a much higher chance of developing Alzheimer’s disease, and at a much earlier age, than other people. Around half of people living with Down syndrome will develop Alzheimer’s disease by age 60. Many people with Down syndrome start experiencing symptoms in their early to mid-50s. 

For more, visit our page on Down syndrome and Alzheimer’s disease:

Risk factors for developing Alzheimer’s disease

There are risk factors for developing all forms of dementia. Some, like your age and genetics, aren’t in your control. But there are 14 known risk factors for dementia that you can do something about. 

Globally, 45% of all dementia diagnoses could be prevented with action on these modifiable risk factors.

To learn more about how you can reduce your risk of developing Alzheimer’s disease and other forms of dementia, visit our brain health and prevention page:

Signs and symptoms of Alzheimer’s disease

Everyone’s experience of Alzheimer’s is unique. Symptoms can be different from one person to another. But it’s common for someone living with Alzheimer’s disease may experience:

• trouble remembering, especially recent events
• repeatedly saying the same thing
• being vague in everyday conversation
• trouble planning, solving problems, organising and thinking logically
• taking longer to do everyday tasks
• language difficulties, such as problems finding the right word
• trouble remembering the time, where you are and who people are
• trouble becoming motivated and starting tasks
• unusual changes in behaviour, personality and mood.

Someone with these symptoms might not be able to recognise their own changes. Often a family member or friend will notice them instead.

If you have any of these symptoms, or if you know someone else who does, talk to your doctor. The sooner you know, the more you can do.

For more on signs of dementia, visit our early warning signs page:

Diagnosing Alzheimer’s disease

At least we knew what we were dealing with – this is what it is and we can deal with it. 

Angela, on her mum Maria’s dementia diagnosis.

Testing for Alzheimer’s disease usually starts with visiting your GP.

Your doctor might:

• talk to you about what changes you’ve noticed and how they’re affecting your life
• talk to people close to you to see what they’ve noticed
• ask about your lifestyle and medical history so they can understand your dementia risk and what other conditions might be involved
• give you a general physical exam and some thinking and memory tests.

Your doctor might refer you to a specialist, like a neuropsychologist. They can do more tests of your thinking, memory, language and problem-solving.

Your doctor and your specialist might:

• recommend lab tests. Blood, urine and other tests can help spot another condition that could explain your symptoms
• refer you for brain scans. These can’t diagnose Alzheimer’s disease, but they can help rule out other causes and get a better sense of any degeneration that’s happened
• recommend a cerebrospinal fluid (CSF) test. This test measures your levels of beta amyloid and tau proteins, but it isn’t required for a diagnosis of Alzheimer’s disease and can be invasive.
• recommend new blood tests for beta amyloid and tau proteins that are less invasive that cerebrospinal fluid tests.

Talk to your health professional about your options. 

Each of these tests is designed to:

1. look for direct evidence of Alzheimer’s disease
2. build up other evidence to suggest a diagnosis
3. rule out other causes of your symptoms.

If the evidence is strong enough and other causes can be ruled out, your health professional may diagnose you with Alzheimer’s disease.

Some people feel shock when they’re diagnosed with Alzheimer’s disease. Other people feel relief. Whatever your reaction, there is support for you. 

Stages of Alzheimer’s disease

Alzheimer’s disease is progressive. This means that symptoms start as mild in their impact and become more serious over time.

Alzheimer’s disease affects different areas of the brain, damaging different abilities. Short-term memory is often affected first, but later, long-term memory is also affected.  

Some people living with Alzheimer’s disease keep their senses of touch and hearing, and also respond to emotion, even in the advanced stages of the condition.

In the final stages of Alzheimer’s disease, many people become immobile and dependent, requiring extensive care.

Alzheimer’s disease has three broad stages: early, middle and advanced. These stages can overlap. They’re not exactly the same for everyone, and they may happen more slowly or quickly for different people.

Early-stage Alzheimer’s disease

Early Alzheimer’s disease is when symptoms are at their mildest. It’s sometimes called ‘mild Alzheimer’s disease’.

Because these changes usually happen gradually, it’s often hard to notice when this stage begins. The processes that lead to Alzheimer’s disease can start up to 20 years before you notice symptoms.

Many people get their diagnosis of Alzheimer’s disease after they have already passed through this stage.

If you have early-stage Alzheimer’s disease, you might:

• appear more apathetic
• lose interest in hobbies and activities
• be less willing to try new things
• be less able to adapt to change
• be slower to grasp complex ideas
• take longer with routine jobs
• have disturbed sleep
• become more forgetful of recent events
• become confused about time and place
• become lost if you’re away from familiar surroundings
• be more likely to repeat yourself or get lost in conversation
• be more upset if a mistake is made
• have trouble managing money
• have trouble shopping or preparing meals.

Middle-stage Alzheimer’s disease

Mid-stage Alzheimer’s disease is the next stage of the disease. It’s sometimes called ‘moderate Alzheimer’s disease’. Your symptoms will become more evident and pronounced. You may find it harder to stay independent. You might require daily support.

If you have middle-stage Alzheimer’s disease, you might:

• forget recent events
• forget the names of your family or friends, or mix-up family members
• forget where objects are or where you left them
• remember the distant past better, sometimes with confused details
• repeat things you say or actions you do
• become angry, upset or distressed through frustration
• get confused about time and place
• see or hear things that are not there
• become suspicious of other people
• become lost more easily
• be less able to perform simple maths
• find it harder to make complex choices
• neglect your personal hygiene
• have increasingly disturbed sleep
• forget to eat
• find it harder to make day to day decisions.

Late-stage Alzheimer’s disease

Late-stage Alzheimer’s disease is the final stage. It’s sometimes called ‘severe Alzheimer’s disease’. Your symptoms will become severe, and you will need care for most or all your daily activities.

If you have late-stage Alzheimer’s disease, you might:

• forget important events from your early life
• forget important information, like where you live
• become unable to recognise everyday objects, friends and family
• become restless
• have increasing trouble with continence
• behave out of character
• have increasingly disturbed sleep
• have difficulty walking
• lose your ability to speak or understand what people are saying
• need help eating, washing, bathing, brushing your teeth, going to the toilet and dressing.

In the final stages of Alzheimer’s disease, you are likely to become immobile and require constant care. How fast this happens is different for everyone.

Though there are treatments that may slow the progress of Alzheimer’s disease, there is currently no cure. Alzheimer’s disease is a terminal condition. The average time from diagnosis to end of life is 7-10 years, but this varies for everyone.

Treatment and management of Alzheimer’s disease

Right now, there’s no known cure for Alzheimer’s disease. However, there are new and promising treatments that have been shown to slow the progression of Alzheimer’s disease symptoms at different stages. 

Lecanemab (Leqembi): treatment for early-stage Alzheimer’s disease

Lecanemab (also known by the brand name Leqembi) is a prescription medicine that binds to beta amyloid protein. This prevents the protein from forming the plaques that damage the brain, and also reduces existing plaques.

Lecanemab does not cure Alzheimer’s disease, but it might help slow its progression and help you maintain independence for longer.

For more information, including how you can find out if lecanemab is right for you, visit the lecanemab section of our page on treating dementia:

Donanemab (Kisunla) for early-stage Alzheimer’s disease

Donanemab (also known by the brand name Kisunla) is a prescription medicine that targets and breaks down amyloid plaques in the brain.

Donanemab does not cure Alzheimer’s disease, but it may help slow its progression and help you maintain independence for longer.

For more information, including how you can find out if donanemab is right for you, visit the donanemab section of our page on treating dementia:

Cholinesterase inhibitors for Alzheimer’s disease

Cholinesterase inhibitors are medications that stop important chemicals in your brain breaking down. Those chemicals, which are called acetylcholine and butyrylcholine, help your brain cells communicate with each other. 

Cholinesterase inhibitors may help improve your memory and your ability to carry out day-to-day activities if you have Alzheimer’s disease.

Cholinergic medications for Alzheimer’s disease

Cholinergic medications work differently to cholinesterase inhibitors. Instead of stopping those important communication chemicals in your brain from breaking down, they either produce more of those chemicals, or they act just like those chemicals, doing the same thing in your brain.

For more information, visit the cholinesterase inhibitors section of our page on treating dementia:

Memantine for Alzheimer’s disease

Memantine targets a different brain chemical, called glutamate, that is present in high levels if you have Alzheimer’s disease. Memantine blocks glutamate and prevents too much calcium moving into the brain cells causing damage.

For more information, visit the cholinesterase inhibitors section of our page on treating dementia.

How Dementia Australia can help

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 younger onset Alzheimer’s disease

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

Further support for Alzheimer’s disease

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.