What's the difference between Alzheimer's and dementia? An expert unpacks the difference between the terms. Photo / Getty images
What's the difference between Alzheimer's and dementia? An expert unpacks the difference between the terms. Photo / Getty images
Niki-Anne Wilson is a post-doctoral research fellow at Neuroscience Research Australia (NeuRA), UNSW Sydney.
Changes in thinking and memory as we age can occur for a variety of reasons. These changes are not always cause for concern. But when they begin to disrupt daily life, that could indicatethe first signs of dementia.
Another term that can crop up when we’re talking about dementia is Alzheimer’s disease, or Alzheimer’s for short.
Dementia is an umbrella term used to describe a range of syndromes that result in changes in memory, thinking and/or behaviour due to degeneration in the brain.
To meet the criteria for dementia, these changes must be sufficiently pronounced in that they interfere with usual activities and are present in at least two different aspects of thinking or memory.
Children with childhood dementia progressively lose all previously acquired skills and abilities.
— The Conversation - Australia + New Zealand (@ConversationEDU) April 26, 2024
For example, someone might have trouble remembering to pay bills and become lost in previously familiar areas.
It’s less well-known that dementia can also occur in children. This is due to progressive brain damage associated with more than 100 rare genetic disorders. This can result in similar cognitive changes to what we see in adults.
Alzheimer’s is the most common type of dementia, accounting for about 60-80 per cent of cases.
So it’s not surprising many people use the terms dementia and Alzheimer’s interchangeably.
Changes in memory are the most common sign of Alzheimer’s and it’s what the public most often associate with it. For instance, someone with Alzheimer’s may have trouble recalling recent events or keeping track of what day or month it is.
We still don’t know exactly what causes Alzheimer’s. However, we do know it is associated with a build-up in the brain of two types of proteins called amyloid-β and tau.
While we all have some amyloid-β, when too much builds up in the brain it clumps together, forming plaques in the spaces between cells. These plaques cause damage (inflammation) to surrounding brain cells and lead to disruption in tau. Tau forms part of the structure of brain cells, but in the case of Alzheimer’s, tau proteins become “tangled”. This is toxic to the cells, causing them to die. A feedback loop is then thought to occur, triggering production of more amyloid-β and more abnormal tau, perpetuating damage to brain cells.
Alzheimer’s can also occur with other forms of dementia, such as vascular dementia. This combination is the most common example of a mixed dementia.
People with dementia may have trouble keeping track of dates. Photo / Getty Images
Vascular dementia
The second-most common type of dementia is vascular dementia. This results from disrupted blood flow to the brain.
Because the changes in blood flow can occur throughout the brain, signs of vascular dementia can be more varied than the memory changes typically seen in Alzheimer’s.
For example, vascular dementia may present as general confusion, slowed thinking, or difficulty organising thoughts and actions.
Your risk of vascular dementia is greater if you have heart disease or high blood pressure.
Some people may not realise dementia can also affect behaviour and/or language. We see this in different forms of frontotemporal dementia.
The behavioural variant of frontotemporal dementia is the second-most common form (after Alzheimer’s disease) of younger-onset dementia (dementia in people under 65).
Actor Bruce Willis was diagnosed with frontotemporal dementia, or FTD, in 2023, with the family writing, "While this is painful, it is a relief to finally have a clear diagnosis."
People living with this may have difficulties in interpreting and appropriately responding to social situations. For example, they may make uncharacteristically rude or offensive comments or invade people’s personal space.
Semantic dementia is also a type of frontotemporal dementia and results in difficulty with understanding the meaning of words and naming everyday objects.
Dementia with Lewy bodies
Dementia with Lewy bodies results from dysregulation of a different type of protein known as α-synuclein. We often see this in people with Parkinson’s disease.
So people with this type of dementia may have altered movement, such as a stooped posture, shuffling walk, and changes in handwriting. Other symptoms include changes in alertness, visual hallucinations and significant disruption to sleep.
Dr Bruce Miller, the Director of Memory and Ageing at the University of California, said that Robin Williams’ brain had the ‘most devastating form of Lewy Body Dementia’ he’d ever seen. #60Minspic.twitter.com/n6RbnVU8Sa
If you or someone close to you is concerned, the first thing to do is to speak to your GP. They will likely ask you some questions about your medical history and what changes you have noticed.
Sometimes it might not be clear if you have dementia when you first speak to your doctor. They may suggest you watch for changes or they may refer you to a specialist for further tests.
There is no single test to clearly show if you have dementia, or the type of dementia. A diagnosis comes after multiple tests, including brain scans, tests of memory and thinking, and consideration of how these changes impact your daily life.
Not knowing what is happening can make for a challenging time, so it is important to speak to someone about how you are feeling or reach out to support services.
Dementia is diverse
As well as the different forms of dementia, everyone experiences dementia in different ways. For example, the speed dementia progresses at varies a lot from person to person. Some people will continue to live well with dementia for some time while others may decline more quickly.
There is still significant stigma surrounding dementia. So by learning more about the various types of dementia and understanding differences in how dementia progresses, we can all do our part to create a more dementia-friendly community.
