Dementia warning signs you might miss
Scientists have uncovered how dementia disrupts the brain's “road network” up to 20 years before symptoms appear, offering new hope for early detection.
We need to go back to basics when it comes to explaining dementia, neurologist Dr Emma Devenney believes.
“If we want to talk to people about treating and preventing it, we have to be able to clearly explain what it is – and what it isn’t,” the National Health and Medical Research Council (NHMRC) early career fellow and Alzheimer’s disease researcher with Neuroscience Research Australia (NeuRA) said.
An umbrella term used to describe a cluster of neurological symptoms, dementia is not a disease in and of itself, and is in fact caused by a number of different conditions.
“What we really mean when we talk about dementia is a progressive decline in functioning,” Dr Devenney told news.com.au.
“So if we see people who are progressively struggling with their day-to-day life, whether that be managing the household, managing their finances or managing at work, we tend to see this progressive decline happening.
“There is a neurodegenerative process going on, and that decline can be for a number of reasons.
“Perhaps they have problems in memory, language, judgment – or all of those things. And that then might reflect the different pathologies that we see that cause dementia.”
Different causes, different brain regions
The past decade has seen an exponential increase in both interest and innovation when it comes to dementia research. And what scientists have learned about the way different types of dementia impact the brain and its regions is rewriting the book on both treatment and prevention.
“Back when I was doing my neurology training there weren’t many neurologists really interested in cognitive neurology,” Dr Devenney said.
“Mostly it was geriatricians who would see people with dementia. Now, that’s changed. And I think it’s because by understanding what is happening in the brain and body, we’re beginning to see a path forward with dementia.
“We’re in a period of more hopefulness.”
Dr Devenney – who is lending her support to news.com.au and The Australian’s Think Again campaign – said new discoveries about how the different regions of the brain interact have facilitated a deeper understanding of how dementia progresses.
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“Your brain, like every other part of your body, is made up of billions of cells called neurons, and they’re all connected to each other in networks,” she said.
“Even a decade ago, we used to think that one specific part of the brain was responsible for a specific function. So, for example, we used to think that the memory centre sat in the hippocampi, which are in the temporal lobes.”
Now, with advanced imaging modalities, Dr Devenney said that understanding has shifted.
The brain is better understood as a massive, interconnected network, similar to a city’s road system. Instead of cars, tiny specialised messengers (neurons) are constantly communicating with each other.
For every function we perform, like remembering a fact or speaking a word, there is a specific network of these neurons working together, and far from being confined to one small area (like Dr Devenney’s example with the hippocampi) it stretches across our entire brain, from the front to the back and even down to the brain stem.
Dementia starts when something disrupts this network.
“The million dollar question is, what is the very first thing that happens?” Dr Devenney said.
“There are lots of theories around. For some people, they have a genetic risk, so something about those nerve cells are more vulnerable.
“For other people, there may be a whole host of reasons – environmental, epigenetic, etc – but something happens, be that inflammation, be that some other process, that causes damage within these nerve cells, and (depending on the disease) might also result in the laying down of abnormal proteins within those cells.”
In Alzheimer’s disease, for example, a naturally-occurring protein called amyloid that is produced in the brain stops being cleared out properly. It begins to build up and forms deposits inside the neurons. This build-up acts like a roadblock, damaging the neurons and eventually causing them to die.
Since the neurons are all connected, when one neuron dies, it disrupts the entire network and prevents the adjacent neurons from working correctly – like a single broken road in a city that causes traffic jams everywhere else.
What is remarkable, Dr Devenney said, is that new research and technology has been able to detect these proteins, in the case of Alzheimer’s, years before symptoms set in.
“We know that the amyloid protein starts to build up 15 to 20 years before any symptoms appear,” she said.
“And things are rapidly changing. We might get to a point – perhaps not too far from now – where we’ll go to the GP and get a blood test, and that test will be able to tell us if amyloid is building up in our brains.
“And with the innovations going on now, and the focus on finding vaccines and treatment, perhaps by then there will be interventional things we can do.”
More than just memory loss
While lapses in memory are often associated with some of the first symptoms of dementia, behavioural, mood and physical changes can often be present first.
A 2025 study published in Age and Ageing journal found behavioural and psychological symptoms (BPSD) are extremely common, affecting up to 90 per cent of people with dementia at some point in their illness.
Frontotemporal Dementia (FTD), for example, is a major exception to the memory-loss-first pattern.
“We talked about the hippocampus and the memory circuits in Alzheimer’s disease in Frontotemporal dementia, which I tend to see a lot of, it usually affects the frontal lobes the temporal lobes, and those are areas that control our ability to inhibit our behaviour,” Dr Devenney said.
“It’s not unusual for people to do things in public that are completely out of character for them, or to become impulsive, start gambling, for example. In people with Frontotemporal dementia, those behaviours do happen before the cognitive symptoms.”
Dr Devenney said because it’s generally a younger onset dementia than other types, this can often delay diagnosis, leading to incredibly painful relationship breakdowns in families where a loved one suddenly begins a path of destructive or abusive behaviour.
A physical – and fatal – decline
What is even less understood in public awareness of dementia, Dr Devenney said, is its physical impacts.
“Eventually, these diseases impact virtually every part of the brain, which of course controls your body,” she said.
“We use our brain to control all of our motor functions – walking, talking, swallowing – and particularly as the disease progresses, people tend to develop other physical symptoms.”
While we need to educate people on how to prevent dementia, it’s also important not to sugar-coat things, Dementia Australia’s CEO Professor Tanya Buchanan said.
“It is a progressive, and ultimately fatal condition,” Prof Buchanan said.
Death is typically caused not by dementia itself, but by complications such as aspiration pneumonia (inhaling food/liquid into the lungs), malnutrition, dehydration, or other infections that the body can no longer fight.
“My sense is that there has been a bit of nihilism around dementia in this county,” Prof Buchanan said.
“Far too many Australians don’t understand what dementia is. They don’t understand that there are things we can do to reduce our risk.”
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