Dementia vs Alzheimer's: what is the difference?

Dementia is not a single disease. It is an umbrella term for a group of symptoms, memory loss, confusion, difficulty with language, and changes in thinking and behaviour, that are severe enough to interfere with everyday life. Alzheimer's disease is the most common disease that causes those symptoms. So the short answer is that dementia describes what is happening to the person, and Alzheimer's is one of the reasons it is happening. Saying someone "has dementia" is a little like saying they have a fever: it names the problem, not the cause.

That distinction matters, because different causes behave differently. Two people can both have dementia and need quite different care, because the underlying disease is different. This guide explains the main types, how a diagnosis works in Australia, and what it means for the support you look for.

Dementia is the symptoms, Alzheimer's is a cause

Think of it as two levels.

• Dementia is the diagnosis of the pattern: a decline in memory, thinking or reasoning significant enough to affect daily activities, and not a normal part of ageing.
• Alzheimer's disease is a specific, progressive brain disease. It is the single most common cause of dementia.

Because Alzheimer's is so common, the two words often get used as if they mean the same thing, including by well-meaning family members and sometimes in the media. They do not. Someone can have dementia caused by something other than Alzheimer's, and in the early stages a person can have changes from Alzheimer's disease without yet meeting the threshold for dementia.

The main types of dementia

There are many causes, but a handful account for most cases.

Alzheimer's disease. The most common. It usually begins with difficulty forming new memories, so the person may repeat questions or forget recent conversations while recalling events from decades ago clearly. It typically progresses gradually over years.

Vascular dementia. Caused by reduced blood flow to the brain, often after a stroke or a series of small strokes. It can begin more suddenly than Alzheimer's and may progress in noticeable steps rather than smoothly. Problems with planning, concentration and speed of thinking are often more prominent early on than memory loss.

Lewy body dementia. Associated with abnormal protein deposits in the brain. It often involves noticeably fluctuating alertness, visual hallucinations, and movement changes similar to Parkinson's disease. People with Lewy body dementia can be very sensitive to certain antipsychotic medications, which is one important reason an accurate diagnosis matters.

Frontotemporal dementia. Affects the frontal and temporal lobes. It tends to appear at a younger age than the other types, and the first signs are more often changes in personality, social behaviour or language than memory loss. Families sometimes describe the person as "not themselves" long before memory becomes an issue.

Mixed dementia. More than one cause at once, most commonly Alzheimer's together with vascular changes. This is more common in older people than was once thought.

Why the difference matters in practice

Knowing the type helps in four practical ways.

1. It explains the behaviour. If you know the frontal lobes are affected, apparent rudeness or loss of empathy reads as a symptom rather than a choice. That changes how a family responds.
2. It guides medication. Some treatments suit some types and are actively risky in others, as with antipsychotics in Lewy body dementia.
3. It shapes what to expect. A stepwise decline after strokes calls for different planning than a slow, steady progression.
4. It points to the right support. Some services and day programs are built specifically around younger-onset dementia, or around behaviours more common in particular types.

Getting a diagnosis in Australia

Start with a GP. There is no single test that confirms dementia; a diagnosis is built from several pieces.

The GP will usually take a detailed history, ideally with someone who knows the person well, since the person themselves may not notice the changes or may minimise them. They will check for other conditions that can mimic dementia, and this step genuinely matters: depression, thyroid problems, vitamin deficiencies, infections and the side effects of some medications can all cause confusion and memory problems, and several of those are treatable. Ruling them out is not a formality.

From there the GP may do a short cognitive assessment in the clinic, then refer on to a specialist, commonly a geriatrician, neurologist or psychiatrist, and arrange brain imaging. A specialist assessment is often where the specific type is identified.

If you want to talk it through with someone who is not your GP, the National Dementia Helpline on 1800 100 500 is free, runs 24 hours a day, and is a good starting point for both people living with dementia and their families.

After a diagnosis

A diagnosis is the beginning of a plan, not the end of the story. Many people live well for years with the right support.

Practically, it is worth doing three things reasonably early, while the person can take a full part in the decisions. Get the legal documents in order, particularly an enduring power of attorney and an advance care directive, because these are far harder to put in place later. Contact My Aged Care on 1800 200 422 to start an assessment for support at home, since services are easier to arrange before there is a crisis. And look at what will sustain the carer, including respite care, which is one of the strongest predictors of whether someone can keep caring at home.

For the range of care available at each stage, from support at home through to a home with a dedicated memory support unit, see our guide to dementia care options in Australia. When you are ready to compare services near you, you can browse verified home care providers on Our Mate.

Frequently asked questions

Is Alzheimer's a type of dementia?

Yes. Alzheimer's disease is the most common disease that causes dementia. Dementia is the umbrella term for the symptoms, and Alzheimer's is one of several diseases that produce them. That is why a person may be described as having "dementia due to Alzheimer's disease".

Can you have dementia without having Alzheimer's?

Yes, and it is common. Vascular dementia, Lewy body dementia and frontotemporal dementia are all causes of dementia that are not Alzheimer's disease. Some people also have mixed dementia, where more than one cause is present at the same time.

Is memory loss just a normal part of getting older?

Some change is normal, such as taking longer to recall a name or occasionally misplacing things. Dementia is different in degree and in effect: the changes are significant enough to interfere with everyday activities, and they get worse over time. If memory or thinking is affecting daily life, it is worth seeing a GP rather than assuming it is simply age.

Which type of dementia is diagnosed most often?

Alzheimer's disease is the most commonly diagnosed cause of dementia, followed by vascular dementia. Because Alzheimer's is so much more common than the others, the two terms are often used interchangeably, though they do not mean the same thing.

Who diagnoses dementia in Australia?

Start with a GP, who will take a history, check for other treatable causes and may do a short cognitive assessment. They will often refer to a specialist such as a geriatrician, neurologist or psychiatrist, and arrange brain imaging. Identifying the specific type usually happens at the specialist stage.