The updated Lancet Consortium on Dementia Prevention, published last year, concluded that 40 per cent of dementia cases could be prevented or delayed by targeting 12 modifiable risk factors, including obesity, type 2 diabetes, physical inactivity, excess alcohol intake and smoking.
Giving up smoking is particularly key, says Joanna Wardlaw, UK Dementia Research Institute group leader and a professor of applied neuroimaging at the Centre for Clinical Brain Science at Edinburgh University.
‘A natural part of the ageing process is that your brain tends to shrink a bit,’ she says, ‘and the more it shrinks, the more you are likely to have problems with cognitive ability.
‘Smoking causes accelerated thinning of parts of the brain, including the grey matter [which processes information]. If someone smokes from the age of 20 and gives up at 30, on average, someone who has never smoked won’t get the same level of damage to the grey matter until they’re 53.’
We all need to realise that the processes that cause dementia don’t just happen in old age, adds Professor Paul Matthews, a director of the UK Dementia Research Institute and head of the Department of Brain Sciences in the Faculty of Medicine at Imperial College London.
‘The FINGER study, which monitored 1,200 people in Finland at risk of cognitive decline [as a result of lifestyle factors such as lack of exercise and high blood pressure] found that interventions to help with diet, exercise and cognitive training significantly improved or maintained cognitive function,’ he says.
‘This was an important finding — the first reasonably large study in dementia to show that you could possibly reverse the progression of early phase cognitive performance loss, with interventions.’
A follow-up trial, METFINGER, is now being run in the UK and other international centres looking at providing lifestyle changes and adding in the diabetes drug metformin, which helps to lower blood sugar in the body.
‘The hypothesis is that metformin can tweak the ageing process of cells, including brain cells,’ says Professor Matthews. ‘It could have a similar effect to the impact statins have had on preventing cardiovascular disease.’
In addition to the usual lifestyle factors that we’re all advised to address, what other steps do the top dementia experts themselves take to ward off the disease?
In bed by 10pm for a good night’s sleep
Dr Ian Harrison, a senior research fellow at the Centre for Advanced Biomedical Imaging at University College London, who specialises in brain imaging, says: ‘When it comes to lowering my own dementia risk, I swear by a good night’s sleep. I used to go to bed later, but for the past three years I’ve been strict about going to bed at 10pm every day, even at weekends.
Dr Ian Harrison, a senior research fellow at the Centre for Advanced Biomedical Imaging at University College London, who specialises in brain imaging, says: ‘When it comes to lowering my own dementia risk, I swear by a good night’s sleep
‘The time I wake up depends on my children, aged one and three, but I set my bedtime early to give my brain the best chance to rest and have a clearout during the night.
‘The brain has a cleaning system, called the glymphatic system, which removes a build-up proteins and waste products.
‘We know from studies that the glymphatic system is 70 per cent more active when we sleep. If there is an impairment in the system due to lack of sleep, then this may lead to a build-up of proteins, including amyloid.
‘Anecdotally, we all know that we have a fuzzy head if we have a bad night’s sleep: this may be due to the glymphatic system not clearing out all the waste products.’
A review of studies by the University of Florida, published in the journal Sleep in 2017, followed up patients with sleep disorders, including obstructive sleep apnoea [where people stop breathing momentarily as they sleep], over nine and a half years and found a higher risk of them developing Alzheimer’s compared with those who had no sleep disturbances.
He says: ‘We know from studies that the glymphatic system is 70 per cent more active when we sleep’
Dr Harrison also makes sure he gets plenty of exercise.
‘We know from animal studies that exercise boosts the function of the glymphatic system,’ he says, ‘so I also go for a run and go to the gym every week, as well as cycling to work.’
Separately, but for the same reasons, Roger Watson, a professor of nursing at the University of Hull who works in care of older people, always switches off his phone at night.
‘The light and potential buzzing can be disruptive to sleep — and studies suggest that broken sleep has an impact on our risk of dementia,’ he says.
Chews on mints with xylitol
Chris Fox, a professor of clinical psychiatry at the University of East Anglia Medical School, and a consultant old age psychiatrist at Norfolk and Suffolk NHS Foundation Trust, says: ‘As well as looking after my health generally, I take good care of my teeth to reduce the risk of dementia.
‘I use mints containing xylitol [an artificial sweetener] to keep the microbiome, the community of bacteria in the mouth, healthy.
‘This not only reduces dental cavities but xylitol actually gets rid of nasty bacteria, too. There is emerging evidence that it creates a healthier oral microbiome.
Chris Fox, a professor of clinical psychiatry at the University of East Anglia Medical School, and a consultant old age psychiatrist at Norfolk and Suffolk NHS Foundation Trust, says: ‘As well as looking after my health generally, I take good care of my teeth to reduce the risk of dementia’
‘One study from Bristol found the same bugs that can cause problems in the mouth were found in post-mortem brains of people who died from Alzheimer’s.’
(Note, xylitol in excess may cause bloating or diarrhoea in those with a sensitive gut.) One suggestion is that oral health may be linked to dementia as the bacteria may trigger inflammation in the brain.
The thinking is that porphyromonas gingivalis, the bacterium in the mouth that causes gum disease, crosses the blood brain barrier — a protective boundary between the bloodstream and the brain.
This can potentially alter brain cells, contributing to dementia, explains Karl Herholz, a professor in clinical neuroscience at Manchester University.
‘We know the disease begins around 20 to 30 years before symptoms become apparent, so it makes sense to have good oral health by brushing and visiting your dentist regularly, which I ensure I do to protect myself against dementia,’ he says.
Avoids walking besides busy roads
Dr Tom Russ, a consultant old age psychiatrist, director of the Alzheimer’s Scotland Dementia Research Centre, at the University of Edinburgh, says: ‘I make a conscious effort to avoid walking along main roads and find back street routes where possible’
Dr Tom Russ, a consultant old age psychiatrist, director of the Alzheimer’s Scotland Dementia Research Centre, at the University of Edinburgh, says: ‘I make a conscious effort to avoid walking along main roads and find back street routes where possible.’
Air pollution was added to the list of modifiable factors to reduce dementia by the Lancet Commission in 2020. This follows studies, including one in Canada of 6.6 million people, that have shown living on a main road is associated with a higher risk of dementia.
Those living within 50 metres of a major road were 7 per cent more likely to develop dementia than people living more than 300 metres away, where fine particulate matter levels [the particles of pollution that can get into the bloodstream] can be up to ten times lower.
‘Pollutant distribution depends on weather conditions, though,’ adds Dr Russ. Heatwaves and high pressure, for instance, can create stagnant air and pollutants are not dispersed — and winds can distribute pollutants over a wide area.
‘There are questions that remain unanswered about pollution and the brain, though. One is whether pollution is just a subtle effect on your thinking skills or does it have a structural effect on the brain.’
There is some suggestion that pollution contributes to brain inflammation, says Gill Livingston, a professor of mental health in older people at University College London. ‘My work is located near one of the most polluted roads in London, so if I walk there I drop back a street and walk parallel to the road, to avoid traffic.
‘It’s why it is also important to try to get away from pollution as much as possible, by spending leisure time or doing exercise in parks or in the countryside.’
She also avoids exposure to wood fires and passive smoking as both produce particulate matter.
Professor Paul Matthews, a director of the UK Dementia Research Institute and head of the Department of Brain Sciences in the Faculty of Medicine at Imperial College London, says: ‘We’ve recently done a study that shows that there is an association between drinking alcohol and higher rates of brain volume loss.
‘In adults, the brain begins to lose half a teaspoon of its size [about 0.3 per cent of its volume] every year, and on average drinking two small glasses of wine a day doubles the rate of volume loss.
‘The base rate is low, though — doubling only increases the volume loss from 0.3 to 0.64 per cent. But we know people who experience more rapid rates of brain volume loss tend to develop more cognitive symptoms earlier than people who don’t have a rapid rate.
‘We have observed this association between alcohol and loss of brain volume in people who drank within the normal range (not excessively), though the effect was larger in those who drank heavily.
Eye & Ear Test
Has an eye test every year
While it’s no surprise to learn that regular hearing tests — and wearing hearing aids when you need them — are key, Dr Emer MacSweeney, a former NHS consultant neuroradiologist and founder of Re:Cognition Health brain clinics, says it is also important to have your eyes checked
It’s now well-established that hearing loss — specifically, hearing loss when you don’t wear hearing aids if you need them — is a leading preventable cause of dementia, and addressing it could reduce the risk by 8 per cent, according to the Lancet Commission on dementia prevention.
Mild hearing loss doubled dementia risk, moderate hearing loss tripled it and severe hearing loss increased the risk by five times.
The theory is that not being able to hear well and the lack of social stimulation that follows is associated with a higher risk of brain shrinkage and damage.
But while it’s no surprise to learn that regular hearing tests — and wearing hearing aids when you need them — are key, Dr Emer MacSweeney, a former NHS consultant neuroradiologist and founder of Re:Cognition Health brain clinics, says it is also important to have your eyes checked.
‘The less well we hear — or lip read, which is key for our understanding of what’s being said — the less opportunity there is to have meaningful conversations that can stimulate the brain.
‘It’s why I make sure I have an eye test at least once a year. And if you think you might need glasses, you should see your optician.’
Doesn’t add salt when cooking
Dr Sarah-Naomi James, a dementia research fellow at University College London, says: ‘Dementia doesn’t just happen in old age, it starts decades before’
Dr Sarah-Naomi James, a dementia research fellow at University College London, says: ‘Dementia doesn’t just happen in old age, it starts decades before. We now know that there is an association between high blood pressure [around 140/90 from midlife, roughly between the age of 40 and 50] and developing dementia.
‘I’m in my early 30s but I look after my physical health and I’m particularly careful about checking salt levels on packets. And I don’t add salt to food, either.
‘Blood pressure tends to rise with age, but there is something about what happens in mid-life that seems to be particularly important, although we don’t know what the mechanism is yet. One theory, though, is the pulsating pressure damages the brain.’
And deliberately uses ‘wrong’ hand
Another step Dr MacSweeney takes is to try to put pressure on her brain by using her non-dominant hand for some tasks.
‘So as well as making sure I brush my teeth and use interdental brushes [to protect against mouth bacteria linked to dementia], I swap hands when using my toothbrush,’ she says. ‘Using the non-dominant hand can provide an additional workout for the brain.’
Similarly, she ‘supercharges’ her exercise regimen.
‘It’s well-recognised that exercise plays a role in helping reduce the risk of Alzheimer’s, with a 2019 study finding that aerobic exercise may specifically help combat changes in the brain associated with dementia,’ she says.
‘But research also tells us that you’ll get an even greater boost if you do a form of exercise that say, unlike jogging, makes you have to think about what you’re doing.
‘So as well as running, I do HIIT — high-intensity interval training — four to five times a week.
Work & Write in Two Languages
Carol Brayne (pictured) says: ”Our brains change quite a bit as we age, in the ways they are wired, and I think at the highest level our brains are meant to be stimulated’
Carol Brayne, a professor of public health at the University of Cambridge, says: ‘Studies have shown that factors such as social engagement, intellectual engagement, having a complex occupation and higher education are associated with a lower risk of dementia, although they don’t eradicate it completely.
‘Our brains change quite a bit as we age, in the ways they are wired, and I think at the highest level our brains are meant to be stimulated.
‘We know that from child development: if you don’t stimulate a child, their brain won’t develop.
‘We are organisms that respond to the environment, and we need stimulation in order to maintain things.
‘My message would be that you need to do things you enjoy, though. Enrich your life by taking up activities that you like and can become better at, at any life stage.