Professor Matthew Kiernan, a neurologist and expert in neurodegenerative diseases, is an unlikely hit at dinner parties.
“When you mention anything about dementia, everyone is interested,” he says wryly. “It’s a thing that we are all engaged with, and it’s a thing that scares a lot of people.”
But Kiernan believes medical science is on the cusp of an important shift that could see dementia cases fall as treatments improve and risk factors are better understood.
“Over the course of my career, heart attack and stroke have shown linear decline in Australia. Why is that?” Kiernan asks. “It’s because we understood these conditions were linked to vascular risk factors and when the risks are adequately treated, strokes and heart attacks become less common.”
Could dementia become a controllable disease too?
“Without doubt,” says Kiernan, director of Neuroscience Research Australia and co-author of research published today in The Lancet Regional Health Western Pacific that explores risk factors for dementia in an area that includes Australia, China and Japan, as well as nations in the Pacific and South-East Asia.
Cases of dementia are projected to nearly triple by 2050 in the region — which has one of the world’s largest and fastest-growing older populations — accounting for more than 50 per cent of global cases.
Professor Matthew Kiernan says lifestyle changes can reduce dementia risk. (Supplied)
The risks you expect and the ones you don’t
Many of the risk factors for dementia – being female, growing older and the genetic lottery — cannot be avoided. Australian actor Chris Hemsworth learnt in 2022 that he carries two sets of the gene ApoE4, one from each of his parents, making him 10 times more likely than average to develop Alzheimer’s disease.
For someone aged 60-64 in Australia, the risk of dementia is about 15 in 1,000 rising to 429 per 1,000 for those over 90 years old.
All around us right now, a little over 410,000 Australians are living with the four main forms of dementia: Alzheimer’s, vascular, frontotemporal and Lewy body dementia caused by Parkinson’s disease. As Australia’s population ages and expands, this figure is predicted to double by the 2050s.
It’s a reality that is particularly poignant for women: Dementia is the leading cause of death for women who make up 63 per cent of dementia cases in Australia.
One of the keys to reducing the odds of developing dementia is addressing 14 modifiable risk factors that can be tackled with lifestyle changes or medication and can be effective in preventing or delaying the onset of dementia in as many as 45 per cent of cases.
The goal is to prevent the epigenetic changes that cause certain genes and chemicals to spring to life and drive the development of dementia.
Many of the 14 risks sound pretty familiar: excessive alcohol consumption, obesity, hypertension, smoking, diabetes, high LDL cholesterol, air pollution and inactivity. Experiencing a traumatic brain injury is another risk.
The impact of a further four risks – differences in education in early life, social isolation, vision and hearing loss — may surprise many. But the explanation is relatively straightforward: the more stimulation your brain receives, the more neural connections it makes, and the better placed it is to delay the impact of cognitive decline.
Untreated depression is on the list
Another worrying risk factor driving dementia that appears on the list for the first time: depression.
Growing rates of depression alongside dementia diagnoses driven by an aging population are a “perfect storm”, Keirnan says.
The exact pathway that leads a person to develop depression is complex and not fully understood. But research suggests part of the picture is inflammation of certain circuitry in the brain and damage from this inflammation may be what drives the onset of dementia.
“Depression is a major modifiable risk factor for dementia and treating depression more effectively through medications, therapy, and lifestyle changes could reduce dementia risk,” Kiernan believes.
Psychiatric medicine is also hard at work finding solutions, he says. Psychiatry is trialling anti-inflammatory treatments such as monoclonal antibodies that suppress the immune system to help treat dementia.
“That’s where the field is now and this research is just starting off,” Kiernan says. “We know from huge epidemiological studies that some of the inflammatory treatments are helpful but we need more investment.”
There has been a 46 per cent leap since 2014 in prescriptions issued in Australia to treat dementia. Four medications are routinely prescribed however there is not yet a magic pill available that can stop or reverse the condition. But Kiernan says promising new candidates are soon to hit the market and the approach to dementia treatment is now “very much in a therapeutic era”.
“That’s why it’s exciting. And I think the message to get out there is that these conditions are treatable,” he says.
The liver’s powerful influence over our brains
If you follow the Parramatta River west from Sydney’s CBD you’ll reach The ANZAC Research Institute where scientist and University of Sydney lecturer Nick Hunt who leads the Biogerontology Group, is researching what’s known as the brain-gut axis and how metabolic disease that leads to conditions like diabetes, also affects our dementia risk.
Hunt’s team is researching new treatments that are delivered to the body using quantum dot nanoparticles.
“The liver is one of the main metabolic hubs of the body. The best way to think about it is as a giant cleaning system for your blood,” Hunt says. “Its job is to process glucose, sense our insulin requirements, look at the nutrients it’s got and balance that relationship. Your ability to clear bad materials is the main challenge and failure to do so is a potential accelerator for dementia.”
Nicholas Hunt from the Anzac Institute in Sydney is researching the use of nanomedicine to deliver treatments for metabolic disease. (Supplied)
In fact, recent research suggests that as many as one in eight people diagnosed with dementia may in fact be suffering from liver diseases, such as cirrhosis. If the liver damage has not progressed too far it is theoretically possible that symptoms of cognitive decline would disappear with treatment.
For Hunt, diabetes research holds great promise in reducing the future development of dementia. Because the brain is one of the body’s most important users of glucose, conditions that reduce liver function — like diabetes — can quickly impact the brain.
“Diabetes isn’t just a condition that affects muscle, or fat or the liver,” Hunt says. “That same glucose imbalance can happen in the brain as well.”
The pattern is so established that some want to give it a name: Type 3 Diabetes.
The theory is that if there is too much insulin in the brain the same enzyme that should be clearing amyloid beta – the substance that can build up causing Alzheimer’s disease – spends its time instead clearing insulin.
“According to the amyloid beta hypothesis that continual build-up of protein causes a lot of those Alzheimer’s symptoms,” Hunt says.
The science is not proven. Recent research undertaken by the ANZAC Institute suggests an important role for the kidneys in clearing amyloid beta.
However new diabetes drugs that improve insulin sensitivity can help Alzheimer’s patients by treating underlying metabolic issues.
And Hunt says there is growing evidence that diabetes drugs like Ozempic, also now used for weight loss, may have potential as a treatment for Alzheimer’s disease with phase three clinical trials already underway.
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Can we reduce the risk to kids?
Whatever the outcome of research into treatments and risk factors the bottom line for most people is ensuring the next generation has less risk of developing dementia than the ones that came before.
While parents are used to the message of avoiding obesity in children by promoting healthy diets, they are not used to the idea that poor food choices they might make for their children could set them up for dementia when they are 65 or 75.
Nick Fuller, an expert in metabolic health at the University of Sydney’s Charles Perkins Centre, says a cluster of metabolic illnesses – high blood pressure, high cholesterol, and elevated blood sugar – can increase the likelihood of developing dementia by 12-30 per cent.
“That’s powerful and impactful,” says Fuller, whose new book Healthy Parents, Healthy Kids aims to teach parents how to pass healthy food, exercise and sleep habits to their children and cut the risk factors for disease. “A family with young children, particularly under the age of five, has a golden window to shape their food preferences for life. But too often we are giving into food demands.”
Raising children to develop good food habits can influence health throughout the lifespan. (ABC Rural: Elly Bradfield)
If you retain any doubt about the value of locking up the treat cupboard then this British research might change your mind. It tracked 3,069 participants from the age of four to 70. Only 8 per cent of people who ate what was considered to be low-quality diets retained high cognitive ability at age 70. Of those who ate high-quality diets, 93 per cent retained high cognitive ability.
“It’s quite challenging to navigate the food environment because our favourite foods are on every corner of every block, screaming out to us. Every time we smell or see them we are releasing dopamine,” Fuller says. “Regularly indulging in processed and packaged foods switches on our hedonic reward pathway making it hard to say no.”
Too many calories lead to a growing waistline and “before you know it you’re clinically diagnosed as having overweight or obesity, then metabolic syndrome, then type 2 diabetes, heart disease”.
He argues that while diet and exercise are vital in keeping metabolic syndrome in check and preventing the development of insulin resistance, sleep is also essential.
A good night of rest can help with mood the next day and make us more likely to make healthy food choices.
Recent research has linked a diet of two or more weekly servings of processed meat from bacon and sausages to hot dogs and salami with a 14 per cent greater risk of dementia. This is likely because these foods are associated with inflammation which in turn is linked to brain aging.
Eating better is linked to a lowered risk because it also lowers the incidence of high blood pressure and other conditions that are known to boost dementia risk.
But research also suggests the amount of sleep you get is linked to dementia risk. Sleeping less than six hours a night when aged in your 50s and 60s, or oversleeping during those years, can increase the risk of developing dementia by 30 per cent. Disturbed sleep is believed to be one of the reasons why those with sleep apnoea are at greater risk of dementia.
What should you do?
So if you are wondering how you can get started today on reducing the risk of a future dementia diagnosis then it doesn’t have to be hard work.
Saying yes to a dinner party invitation — eating well, of course, learning something new and dosing up on social interactions — is just the kind of lifestyle medicine that can help cut dementia risk.
If your hearing is a bit dodgy, then hooking up some hearing aids to keep brain pathways firing, is the way to go.
And you could do worse than ending the day with some quality shut-eye which will allow the brain to reset, and rid itself of amyloid beta build-up, which is found in Alzheimer’s patients.
Alongside new drug developments, the landscape for treating dementia is changing. “It’s incredibly exciting,” says Professor Kiernan.