Dementia prevention: How to reduce your risk
A team of ageing experts, sleep scientists and psychologists at Monash University in Melbourne, are conducting a major study called BetterBrains to see whether personalised lifestyle interventions can help slow signs of cognitive decline. They are examining 40 to 70-year-olds with a family history of dementia over the course of two years.
It is one of the first trials to examine the brain health of a group of midlifers and examine whether changing at least one lifestyle habit – from sleep and exercise regimes to how much they socialise – can stabilise and improve their trajectory.
“Because lifestyle factors are so interconnected, the idea is that improving one would then lead to improvements in another, particularly as the participant gains confidence and mastery of their health,” says Yen Ying Lim, an associate professor at Monash University who is leading the trial.
It follows a string of studies over the last four years which have indicated that many cases of dementia could either be delayed or prevented altogether.
Can I reduce my risk of dementia?
There is hope in slowing down and delaying the onset of age-related cognitive decline. In 2020, The Lancet Commission issued a landmark report led by 28 dementia experts around the world which found that modifying 12 risk factors over the course of a lifetime would be sufficient to prevent or delay 40 per cent of all dementia cases.
The highlighted risk factors were:
Hypertension
Depression
Air pollution
Subsequent studies have not only confirmed these risk factors for cognitive decline but sought to pinpoint how they impact particular brain regions associated with long-term memory and so-called “fluid intelligence”. The latter comprises our capacity to think on our feet, recall information and use this to problem solve.
Last month, a new study, based on 40,000 people from across the UK, identified a set of brain areas which not only develop late, during adolescence and our early 20s, but degenerate earlier and faster than the rest of the brain. It also found that we potentially prevent this degeneration by avoiding getting Type 2 diabetes, not consuming alcohol to excess and limiting our exposure to air pollution.
Pollution is perhaps the one we can do least about, unless you have the ability to move somewhere remote, but ageing experts feel that this shows we can all reduce our dementia risk through leading a healthier life.
“I think the data is now reasonably compelling that through lifestyle modifications we can at least slow and delay the onset of age-related cognitive decline,” says Dr Ronald Petersen, who directs the Mayo Clinic Alzheimer’s Disease Research Centre.
Risk factors we can’t control
There are still some inherent risk factors for dementia which are less modifiable, both the biological changes which occur as a consequence of ageing, and the genetics we are born with.
Age
As we get older, we become more vulnerable to atrophy, a process where our brain slowly shrinks in size with every passing decade. As our brain becomes smaller, we tend to lose brain cells and the connections between them, making cognitive impairment more likely.
Studies have also shown that ageing is accompanied by a steady rise in low-grade inflammation throughout the body, including the brain, and the production of toxic molecules called free radicals, all of which can damage the brain’s fragile blood vessels, drive cell loss and push us closer to dementia.
Genetics
Dr Petersen likes to describe genetic makeup as “setting your deck of cards for the way your life might play out”. In particular, a gene called apolipoprotein E (APOE) has been linked to Alzheimer’s, the most common form of dementia, for more than three decades.
We now know that there are many different variants of APOE, but a particular version called APOE4 significantly increases your risk of Alzheimer’s.
Around one in four people inherit a single copy of APOE4 from their parents, making them already three times more likely to get Alzheimer’s than people without the variant. But around one in 50 people carry two copies of APOE4, including the Hollywood actor Chris Hemsworth, and their risk is two times greater than people with just a single copy.
In 2022, a team of scientists from Massachusetts Institute of Technology published a study which revealed for the first time why APOE4 creates vulnerabilities in the brain. They found that people with the variant have lower levels of myelin, a protective coating for nerve cells in the brain, which makes them more vulnerable to accumulating damage over the course of a lifetime.
We are still learning more about how genetics influences risk of different dementias. Last year, a study identified seven clusters of genes which appear to make certain brain areas more vulnerable to accelerated ageing. However, Dr Petersen points out that lifestyle still plays a significant role in dementia development and many people with a high genetic risk, such as two copies of APOE4, do not go on to develop the disease.
“Genetics aren’t the complete determinant of what’s going to happen to you,” he says. “You can certainly do things in your life that will alter the way your genetics will play out over time.”
Protect your hearing to protect your brain health
One of the most important things to look after is your hearing. The Lancet Commission’s analysis estimated that hearing loss plays a greater role in driving dementia risk in the population than diabetes, smoking or physical inactivity.
As a result, Professor Julia Sarant of the University of Melbourne believes that having regular hearing tests during midlife and having a hearing aid or cochlear implant – a small electronic device which is surgically inserted into the ear – fitted when needed, can play a major role when it comes to preventing or delaying cognitive decline.
Prof Sarant runs a study called Enhance, which specifically looks at how hearing aids can protect brain health in later life. After three years, the latest results have found that the participants with hearing aids are more likely to stabilise their cognitive function, while those without aids saw a decline in working memory, attention, and motor control.
She explains that decreased auditory stimulation to the brain is thought to accelerate the deterioration of vital brain structures and loss of function.
“When there is hearing loss, cognitive resources are reallocated due to the need for greater resources for processing sound,” says Sarant. “This affects other functions such as memory. Older adults with hearing loss also tend to participate less in social events, which could also contribute to cognitive decline.”
Scientists are now trying to understand whether wearing a hearing aid can actively restore lost brain functions in people with mild cognitive decline. This is still unclear, but one seven-year study of older adults with cochlear implants, some of whom had cognitive decline, seemed to indicate that they were less likely to go on to develop dementia.
Keep physically active
Some research has suggested that regular aerobic exercise – defined as any physical activity which raises your heart rate, whether that’s swimming, running, cycling or playing sport – can help slow the rate of brain shrinkage in later life.
But it isn’t just about keeping your heart functioning well. Retaining strength is also just as important. Data collected from more than 450,000 people across the UK has also found that older individuals with greater amounts of lean muscle mass have a 12 per cent lower risk of Alzheimer’s, suggesting that strength training is also important for preserving your cognitive faculties.
“In recent years, there’s been an increase in studies indicating the importance of strength training for older adults,” says Dr Lim. “This is absolutely the case as it can reduce frailty, reduce incidence of falls, and in turn, improve a person’s ability to continue to maintain independence, which then has flow on effects on cognitive health.”
Keep mentally active
Retaining purpose in the second half of your life is felt to be critically important for building and maintaining cognitive reserve, an extra capacity which makes your brain more resilient to age-related changes and damage inflicted by bad lifestyle habits.
Neuroscientists believe that excess cognitive reserve is the reason why some people in their 80s, 90s and over 100, can still function just as well as those many decades younger.
This comes down to staying mentally active, either through continuing to work full-time or part-time or finding fulfilment through community groups, hobbies, and pursuits. Dr Lim believes that it is important not to shy away from things which seem daunting.
Take up challenging new skills
“I would encourage people to engage more in activities that challenge them a little,” she says. “Learning a new language; trying a new skill like knitting, painting, or woodworking; doing things which enable you to connect socially with other people, as social interactions and engagements are also key to brain health.
“In the physical activity space, the term ‘progressive overload’ is used to describe the process of adding a manageable amount of challenge over time to build strength and fitness. The same concepts apply to cognitively stimulating activities.”
Protect your head
The brain is a fragile organ which can be easily damaged by repeated traumas. Research into the long-term consequences of contact sports such as football, rugby, boxing, ice hockey and American football has shown that athletes who incur multiple head injuries over the course of their careers can develop a progressive brain disorder called chronic traumatic encephalopathy (CTE) which leads to dementia. One study from the University of Glasgow, which examined the causes of death of 7,600 former professional footballers, found that they had a three and a half times greater risk of CTE than the average person.
But it isn’t just athletes who are vulnerable. Research following military veterans from the Vietnam War has found that those who suffered head trauma were much more likely to develop some form of cognitive impairment later in life.
Even more scarily, just a single traumatic event can be sufficient to raise your risk of dementia many decades later. Academics at the University of Pennsylvania found that a single blow to the head, sufficient to cause loss of consciousness, was enough to increase a person’s dementia risk by 1.25 times, with the risk continuing to increase with the number of traumas.
“The way I interpret this is when you have trauma to the brain, you reduce your cognitive reserve as you age,” says Dr Petersen.
“As we all age, things build up and we become less cognitively acute. But to an extent, we have some ability to compensate for losing memory and attention, and we can work around that. But trauma reduces this resilience.”
Eat a balanced diet
While the role of diet is often overlooked when it comes to dementia, nutritionists say it plays a major role in whether people develop hypertension or Type 2 diabetes. Because of this, Alzheimer’s disease has sometimes been dubbed ‘Type 3 diabetes.’
Dr Hussein Yassine, an associate professor at the University of Southern California, who studies the impact of nutrition on dementia risk, says that the best evidence for promoting brain health in later life lies with the Mediterranean or Mind diets.
“We know that this is a lifestyle pattern that’s associated with increased consumption of good fats such as omega-3s, olive oils,” he says. Dr Yassine says that these diets are abundant in fibre-rich foods such as avocados, nuts, and beans which contain polyphenols, plant chemicals which can help to neutralise toxic molecules called free radicals which age the body.
“These plant fibres play an important role in shaping the gut microbiome by producing metabolites with anti-inflammatory properties. So if you look at these dietary components, and then add that to a lifestyle where you’re being active, staying cognitively stimulated, they all synergistically interact, to lead to better brain outcomes.”
Manage stress and get enough sleep
Chronic stress has often been linked with dementia due to the negative impacts of the hormone cortisol, often dubbed the stress hormone, on brain health over extended periods of time. Clinical studies have shown that consistently elevated cortisol is associated with poorer episodic and spatial memory, processing speed, language, decision making and social abilities, all factors associated with the onset of dementia.
Getting sufficient sleep plays a major role in the body’s ability to handle stress, but sleep also has its own relationship with dementia risk. Neurologists have found that people with the most irregular sleep patterns, such as those with chronic insomnia or long-term shift workers, have the highest risk of dementia.
“Sleep health recommendations often focus on getting the recommended amount of sleep, which is seven to nine hours a night, but there is less emphasis on maintaining regular sleep schedules,” says the sleep scientist Dr Matthew Pase of Monash University. “The regularity of a person’s sleep seems to be an important factor when considering a person’s risk of dementia.”
This is thought to be because regularly changing sleep patterns impacts the brain’s ability to cleanse itself of toxins during the deep sleep phase, something which can lead to accumulating damage over time.
Don’t smoke and drink less
While consistently drinking more than 14 units of alcohol per week over many years has long been known as a dementia risk, smoking is perhaps an even bigger risk factor. Overall, estimates suggest that as many as 14 per cent of dementia cases worldwide may be directly linked to smoking.
Much of this is related to vascular problems or the damage which smoking causes to the blood vessels in the brain, along with the damage which the toxins in cigarette smoke can inflict on brain cells.
However, a new study in the journal Neurology has identified a completely new pathway, linking smoking and dementia. Using data from 8,360 Canadian women, it found that smoking can accelerate the onset of menopause, and women who undergo menopause before the age of 49 have a far greater risk of thinking and memory problems later in life.
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