Need to know
People living in Western nations today can expect to live a considerably longer life, on average, than 100 years or so ago. The dramatically shorter average life expectancies of the past were skewed by tragically high rates of infant mortality. Nonetheless, compared with the mid-19th century, an average five-year-old today can expect to live to 82 rather than 55 – an extra 27 years (based on data from England and Wales).
Although this is obviously a welcome development – largely brought about by improvements in healthcare and the defeat of infectious diseases – it is a double-edged sword. The body could well keep going throughout all these decades, but the brain might not; and, if you are left able-bodied but with a permanently compromised brain, then you will be in an unenviable position. Such is the concern that a recent survey by Alzheimer’s Research UK showed that, for almost half of the respondents, dementia is the condition they fear the most, rising to more than 60 per cent among those aged over 65.
I have worked in the area of brain health for almost 20 years in my role as a psychiatrist, and one of my major areas of interest is dementia (a progressive loss of brain function due to an illness, such as Alzheimer’s disease). I’ve come to believe that everyone should be thinking about their brain health much earlier than the age of 65. That’s because there are ways to substantially reduce your risk of dementia and cognitive impairment, and the earlier you address problematic lifestyle choices and health conditions, the more successful you are likely to be.
Avoiding dementia is only one consideration, however. Of equal importance is optimising brain function throughout your lifespan – allowing this vital organ to function at its best in the many decades before dementia becomes most relevant. Doing this will help you enjoy greater productivity, happiness and life satisfaction.
Ageing changes the brain, but it’s not all bad news
When considering ways to optimise your brain health, it’s useful to be aware of the forces acting in the opposite direction. In general, the brain fails for a number of reasons:
- When it does not receive optimal fuel for growth and maintenance – both in the form of oxygen and vital nutrients. This could be due to diminished blood supply or an inadequate nutrient consumption.
- Through the accumulation of ‘debris’. Debris builds up in the brain over time as a byproduct of metabolic processes, and its presence is magnified by things we do and don’t do with our lives. This debris can be inflammatory in nature – ie, produced as a response to a perceived threat to the brain – and this inflammation accelerates with age – a process known creatively as inflammaging. Inflammation underpins multiple chronic health conditions including dementia.
- When it is damaged by physical injury. Even relatively innocuous events, such as heading a soccer ball can, if frequent enough, cause long-lasting cognitive problems (more on this in the next section).
- Through lack of training. The brain, like a muscle, can be trained. Unfortunately, just as our bodily muscles wither if we don’t use them, this also means a lack of training and mental activity can lead to a loss of cognitive function and brain failure.
The longer you live, the more time there is for these forces acting against brain health to accumulate. So what does that mean for the ageing brain, even one that manages to avoid injury or illness? Well, there is good news and bad.
The bad news is that you should anticipate some decline in ‘brain-power’ as you grow older, potentially as early as your 30s:
- Forgetfulness can occur, but perhaps the most obvious problem is a loss of processing speed. I’m in my mid-40s and can definitely attest to this. I can usually get to the right answer in the end, but it takes me longer. Playing quick-fire trivia with my teenage son is a lost cause.
- There is also a deterioration in ‘executive skills’ with age, including those governed by the prefrontal cortex (at the front of the brain), which can compromise your ability to plan and organise yourself, and to solve complex problems. Again, this is worse when you are under pressure of time. These changes in cognition are correlated with changes in the brain – shrinkage (which is a proxy of neuronal loss) – and changes in blood supply.
The good news is that certain cognitive skills do not decline drastically with age: your vocabulary and language ability are likely to remain relatively intact (aside from more ‘tip of the tongue’ moments probably related to our slowed processing speed). Likewise, your visuospatial skills will probably survive well with ageing. These enable you to know where you are in relation to other things in our environment – handy when you are driving! Increasing wisdom and experience can also offset a number of the age-related deficits – leading to better decision-making.
What’s more, you don’t have to passively accept any ageing-related changes. Until fairly recently, it was considered that once the brain had matured – by your mid-20s – that was it, all downhill from there. We now know this is not true. Mounting research suggests that, in certain brain structures, humans continue to grow new nerve cells throughout life. One of these, the hippocampus, is critical for encoding new memories, and is an early site of damage in Alzheimer’s disease. The ability to promote this growth, to exploit the brain’s ‘neuroplasticity’ (ie, its sustained ability to adapt to the demands placed on it), presents an important and optimistic opportunity. It means that there are lifestyle changes you can adopt, which I’ll outline shortly, that will help you maintain your general brain fitness and function, even as you grow older.
The roots of dementia run deep
Compared with normal ageing, dementia reflects a far more serious impairment of function. It gets worse with time and, as the disease underpinning it spreads throughout the brain, more cognitive skills will become affected. It is worth mentioning here that dementia is not a diagnosis itself; it is just a term we use to describe a set of symptoms and signs that signify a problem with cognition that is becoming progressively worse. Alzheimer’s disease is the most well-known and frequent cause, but vascular disease (that of the heart and blood vessels) can also cause dementia; frontotemporal dementia, and Lewy body dementia are other common variants.
One of the challenges with tackling dementia is that it is predominantly a condition that manifests in the elderly, yet its roots are very deep. In fact, we now know that one of the toxic proteins associated with Alzheimer’s disease can start to appear in the brain decades before symptoms appear. Likewise, vascular problems, such as high blood pressure and high cholesterol, can develop many years before the illness becomes evident.
This highlights the importance – and, on a positive note, the opportunity – of addressing risk factors well before the symptoms of dementia become apparent. Bear in mind an important and under-recognised point – dementia might well be preventable, or at least delayable. A report in 2020 commissioned for the leading medical journal The Lancet concluded that up to 40 per cent of cases of dementia worldwide could theoretically be avoided by addressing a number of modifiable risk factors throughout life.
This is easier said than done – as anyone who has tried to sustain good habits and abstain from bad habits over the long term knows, keeping motivated can be difficult. This is especially the case when there is often an immediate reward for the bad habit (eg, the sugar rush with eating sweetened foods). We are geared toward such rewards – they are steeped in our ancestral history when the threat was scarcity. The current threat in the modern Western world, however, is not scarcity, but abundance. Never before have we had such easy access to things that are harmful to our brain, chief among them: sugar, saturated fat, and salt. The combination of their ubiquity and our hard-wired desire for them is a real problem.
Nonetheless, despite these challenges, the fact remains that there are things you can do to protect your brain from dementia. What’s more, these activities also promise immediate rewards of their own – both in terms of improved cognitive function and better general wellbeing. In fact, to protect your brain health for the future and to optimise your brain function in the here and now, you should be addressing the same things, and in this Guide I will show you how.
What to do
I propose five main categories of intervention you can follow to optimise your brain function, both immediately, and to help reduce your risk of developing dementia later in life.
Nourish your brain
The brain accounts for only 2 per cent of your bodyweight yet uses 20 per cent of its energy requirements. It is not surprising then that, if it is not receiving the right fuel, it will not operate well. Achieving this requires both the right nutrients being taken in and also an adequate transport system to get them to the brain.
The latter relies on good vascular health, including the absence of atherosclerosis, a fatty deposition on the inside of blood vessels that narrows them. This is related to your cholesterol level as well as your blood pressure. Abnormal blood pressure also directly impacts upon the nutrient supply to the brain: too high, and you run the risk of strokes; too low and the flow could be inadequate to ferry nutrients to the brain in an efficient fashion. Crucially, a healthy diet can help ensure your blood pressure and cholesterol levels are in good shape.
The most evidence-based diets for brain protection are the Mediterranean diet or its close cousin, the MIND diet – short for the Mediterranean-DASH intervention for Neurodegenerative Delay, where DASH itself is an acronym for Dietary Approaches to Stop Hypertension (hypertension being the medical term for high blood pressure). You can see why the acronyms were developed! A study looking at the benefits of the MIND diet showed that participants who followed it most rigidly had brains that were the equivalent of seven years younger (based on cognitive abilities) than those who did not follow it at all.
Both the Mediterranean and MIND diets suggest foods to be included and foods to be excluded, or at least minimised:
Foods to include:
- Green leafy vegetables and other preferably non-starchy vegetables
- Spices and herbs
- Legumes and beans
- Cold-water fish – salmon, tuna, sardines and the like
- Olive oil
- Nuts and seeds
Foods to be wary of:
- Processed and sugary foods
- Dairy and red meat
The basic idea with all these foods is to get a plentiful supply of antioxidants (compounds that have a protective effect in the brain), fibre, unsaturated fats (including Omega-3 fatty acids), B vitamins and an adequate amount of complex carbohydrates.
Earlier, I mentioned inflammation as a cause of poor brain health. Antioxidants in the foods above – especially the vegetables and spices – dampen inflammation by neutralising free radicals, which are molecules that are produced as part of everyday bodily functions, such as breathing, eating and physical activity. They are produced in excess in response to other things – air pollution, smoking, alcohol and processed foods, to name a few. If the inflammation reaches the brain, this sets the scene for cognitive problems, including dementia.
Fibre seems to be of special benefit and is generally lacking in the traditional Western diet, owing to our overprocessing of food. Among other things, fibre causes changes in your gut bacteria – your microbiome – that might be favourable. When the microbiome is not healthy, this again leads to inflammation, in part because the slimy protective layer lining the gut wall is broken down, meaning that inflammatory substances cross over into the tissues and circulation, and potentially adversely affect the brain.
The brain is 60 per cent fat and so I do not generally recommend a low-fat diet for this reason. The right type of fat is critical for insulating the nerve cells so that messages can be transmitted efficiently. The problem with fat is our predilection to consume the wrong type – saturated fat, which is the type in full-fat dairy products and red meat. This type can increase vascular disease – not good for the brain – and excessive quantities can lead to obesity, which is yet another cause of inflammation. If possible, you should be preferencing unsaturated fat – that’s the variety found in olive oil and nuts, for instance.
Train your brain
‘Cognitive reserve’ refers to the brain’s capacity to function well despite physical damage caused by injury or illness, such as Alzheimer’s disease. The higher the reserve, the better off the brain will be. Various factors, such as higher levels of education and cognitively demanding careers, are associated with having greater cognitive reserve, but you can also take proactive steps to train your brain and boost your cognitive reserve.
To train your brain in an optimally effective way, certain conditions are necessary. Firstly, it is generally accepted that novelty and diversity are required – doing things your brain is not used to. Perennial crossword addicts might be better off doing sudokus, and vice versa. Learning a new language, dance style or musical instrument are also great examples of this. Repeated practice is also of particular benefit in helping improve a specific cognitive skill – this consolidates the neural circuitry underpinning the skill. Then there is the complexity. Harder cognitive tasks tax the brain more and will be of more benefit: this is akin to pumping iron in the gym – the real gains are made by pushing yourself. A final condition – progression of complexity – is related to this; essentially, it means continually ratcheting up the difficulty level of your learning or mental activity so that you are sufficiently challenged.
I am often asked about brain-training apps such as Lumosity and BrainHQ. Although these can be enjoyable and addictive (which, on the plus side, encourages continued training), there is so far a lack of robust evidence that the skills developed through these apps become generalised. That is, you will get better at the particular game you are playing, but this might not translate to other cognitive activities or domains of life. The ACTIVE study published in 2013 suggested there might be some generalisability, but this went against the trend of other findings, and more research needs to be conducted. The addictive potential of these games and apps has its downsides too: I have seen a number of patients who had become fixated on bettering their scores on games, and spent hours each day practising at the expense of other important activities, such as socialising (more on that in a moment). These individuals often became stressed when they were not progressing, and this itself is not good for the brain. As with everything, it is a matter of balance.
For memory-optimisation in particular, there are many tricks and techniques that can be employed. Clumping larger pieces of information into smaller ones can be helpful – we naturally do this when breaking up mobile numbers. Rhyming and using songs can help. Testing yourself on what you’ve learnt is beneficial, and ‘spaced repetition’ (restudying material after a break of hours, days, weeks or more) is a powerful tool for remembering.
There are more advanced techniques, as used by ‘memory champions’, that can also be incredibly powerful for memory. The two most well-known are the Peg Method and the Memory Palace (or Method of Loci). Both involve ‘attaching’ whatever it is you want to learn to an already familiar image (the peg) in your mind. Our visual memory is particularly robust, and these methods capitalise on this fact.
The more unusual the entwined image, the more it is likely to be remembered, so creativity is key. As an example, using the Peg Method, your first four pegs might be a gun, a shoe, a tree and a door (these rhyme with numbers one, two, three and four, helping you to remember them, and in order). Now let’s say you are trying to remember four items to get while shopping – fish, bread, yoghurt, and rice. You would then entwine the fish with the gun (creatively, a picture of a huge fish with an Uzi telling you to put your hands up: the humour of the image helps you remember); the bread with the shoe (imagine the squishiness of having a sliced loaf tied to your feet as you walk – make it multisensory); and so on.
The Method of Loci is similar but also uses places (the loci) to help. These places will ideally be highly familiar – your house, for instance. If you had a list of 10 things to remember, you could imagine walking through your house and ‘attaching’ the items on the list to various places in it (in this way, the locations are similar to pegs). Mentally re-walking through the house then brings back the entwined images – and hence whatever you want to remember – with remarkable accuracy.
Through using memory techniques such as these, you win twice over – you might compensate for any deleterious effects of ageing on your memory and, through being mentally active, you will keep your brain sharp and build your cognitive reserve.
Care for your mental health (and connect with others)
Use of the terms ‘brain health’ and ‘mental health’ makes it sound like these are two separate things, but in reality they are deeply intertwined. Two of the most common mental health problems – depression and anxiety – can both have harmful effects on the brain, alongside their more obvious effects on mood and emotion. If you have experienced these debilitating conditions, you will appreciate the short-term effects – slowed thinking, memory and concentration difficulties, brain fog and the like. In extreme cases, they can be severe enough to mimic dementia.
Longer-term, there is an equally problematic outcome that arises when chronic mental health problems are left untreated, and much of this is probably driven by inflammation. There is clearly a ‘dose effect’ – the longer and more severe the episode of depression, for instance, the worse the ramification for your cognitive health – and studies have shown that these mental health problems can alter the structure of the brain. The hippocampus, the brain structure that I mentioned earlier as being critical for memory and that gets damaged in Alzheimer’s disease, is shrunken by protracted episodes of depression. There is good news, however – treating depression with medications has been shown to improve hippocampal growth and health.
The intimate relationship between mental health and cognitive/brain health is yet another reason to take mental health extremely seriously. Lifestyle interventions are a critical component of maintaining mental wellness, so prioritise your sleep, exercise regularly, and eat healthily. If you do find difficulties with your mood, relationships or outlook becoming a significant and lasting problem, don’t bury your head in the sand. Speak with a trusted friend or family member about how you’re feeling, and please don’t be afraid to discuss you concerns with a health professional – whether it be your GP, a counsellor, psychologist or psychiatrist. There are effective treatments available, both psychological and pharmacological, and not only can they help to address your immediate problems, but they can also help protect your brain health longer term.
One of the key influencers of mental health is our degree of social connection, and if this is lacking, especially when it results in a feeling of loneliness, then the brain suffers, and the risk of dementia is raised. Again, this could be in part mediated by inflammation – both social isolation and loneliness have been shown to increase the levels of inflammatory markers in the blood. Feelings of loneliness can result in a host of other problems – mental illness and physical health problems alike – and these can also have a negative effect on the brain. For these reasons, some experts have even likened loneliness to a ‘disease’ that alters the brain’s structure and function.
Conversely, socialising in effect trains the brain and builds cognitive reserve. The to and fro of conversation requires considerable brain power – you have to pay attention to what is being said, keep it in mind, formulate a response, and exercise good social judgment. All these skills are worth honing. Consider the findings from a decades-long British study involving thousands of government employees – those who were more socially active with friends during their 30s, 40s and 50s had superior cognitive performance at the end of the study and, moreover, those who were more socially active in their 60s were at less risk of dementia later on.
It is therefore important to stay connected: reach out to friends and family – online or by phone if you can’t meet. Look at what community groups you might investigate. Join a book club or walking group. Websites such as Meetup are useful for finding out what is going on around you. Even going for a stroll in your neighbourhood – with your dog, if you have one – can be a good opportunity for social contact.
Train your body
Just as mental health and brain health are deeply entwined, so too are your overall physical health and your brain health. Indeed, there is good evidence that improving general physical fitness improves brain health. One reason is obvious – better fitness equates to better vascular health, which then improves the supply of oxygen and nutrients to the brain. Exercise helps our grey matter in other ways, however. Over the long term, it is associated with reduced inflammation, and can offset some of the damage wrought by eating sugary or fat-laden foods. It also helps with weight management, sleep and mental health, with consequent benefits to brain health.
Another protective role comes from the production of a substance called brain-derived neurotrophic factor (BDNF). This molecule is extremely helpful for promoting brain growth and health, and its levels are increased by working out. BDNF is often referred to as ‘miracle gro’ for the brain.
Experts are working on physical activity guidelines specifically for the brain, but for the moment we go by the general guidelines for physical health. These suggest doing at least 150 minutes of moderate-intensity aerobic exercise per week, or 75 mins of vigorous exercise. Moderate means at a level where you can talk but not sing! Cycling, running, brisk walking and swimming are all good examples. It is also suggested that you incorporate resistance training into your regime – using external weights or your own bodyweight – at least twice a week.
Research also supports the notion that high-intensity exercise can be especially beneficial for your heart and so likely your brain. HIIT training (high-intensity interval training) – where you are training near the limits of your cardiovascular capacity for a sustained period – is a classic example of this, though you could also consider simply incorporating sprints into your run or steep hills into your walk.
Obesity also needs to be discussed in the context of training the body. Obesity increases the risk of vascular disease, which then increases the chance of developing dementia. It is also an inflammatory condition, which is not favourable to the brain. Not all fat is created equal, however. Abdominal fat, which in excess leads to central obesity, seems especially malignant. It is a proxy of the fat around our internal organs, and this is especially problematic. Managing weight and watching your waist (following the diet and exercise tips I’ve outlined in this Guide) is therefore an important part of managing brain health.
Protect your brain
The aforementioned exercises and lifestyle choices will help to promote your brain health, but these steps will be to some extent in vain if you are unfortunate enough to suffer a brain injury. In my work, I have seen a number of patients with head injuries, often received in accidents or sometimes assaults. The cognitive consequences of these can be catastrophic. Of course, it is not possible to cocoon ourselves in cotton wool every moment of every day, but there are sensible steps you can take to reduce the risk of sustaining a head injury as you go about your everyday life.
I’m talking here partly about contact sports, including football (soccer!), American football and rugby (in addition to boxing, of course). Studies have shown higher rates of cognitive deficits in those who have played these sports professionally. There is also evidence of chronic traumatic encephalopathy (CTE), a sign of physical damage in the brain, at above-average rates in retired sports stars – whether it be in rugby, soccer or football.
CTE seems to be the consequence of a build-up of tau, one of the proteins implicated in Alzheimer’s disease, and carries with it a higher risk of dementia. I personally recall working in a memory clinic in north Wales and seeing a disproportionate number of elderly men with dementia who had regularly played football throughout their earlier lives. They played with a heavier ball which no doubt, being Wales, was often sodden. The weight of this ball would have been several kilos, and these men would have headed it thousands of times. It seems very likely to me that there was a causal link. Recently, research from Glasgow has shown that your position on the football field influences your risk of dementia, and this in all probability relates to how much you head the ball. You are safe as a goalie; being a defender, however, carries the greatest risk.
Although I would certainly not want to see an end to these sports, I would recommend, from a brain health perspective, avoiding participating in ones where there is a high risk of head injury. If you insist, then wearing protective headgear is crucial and there should be clear local guidance around managing concussion sustained during play. Although many would disagree, I am also not convinced that heading the ball in soccer is a critical part of the game, and would advise against it, especially high-impact heading.
Sleep is another key ingredient in brain protection. I already mentioned it as part of a healthy lifestyle in the context of mental health, but it also deserves to be considered as in important factor in its own right. Sleep helps clear the brain of compounds that would otherwise damage the brain, and hence it is protective. Chronic insomnia is associated with an increased risk of dementia, as well as acutely impairing cognitive ability. Being a lifelong poor sleeper myself, I do take some solace in the fact that chronically poor sleep will not inevitably cause dementia, but there is a link.
The protective clearance mechanism of sleep is mediated through the glymphatic system, a recently discovered series of vessels that run alongside the blood vessels in your brain. When you are asleep – especially in the deepest stages – the glymphatics are especially active and serve as a ‘brain-wash’, their fluids flowing through the brain tissue and flushing away proteins such as amyloid and tau. Prioritising your sleep is therefore critical for maintaining your long-term brain health. Of course, it won’t help if you become overly anxious about getting enough sleep, but the research suggests that we should treat sleep not as an inconvenience that interferes with our busy lives but as an important part of a healthy lifestyle. Try to establish a predictable bedtime routine that helps you relax and unwind; avoiding caffeine or too much alcohol will also help your sleep. These are all part of good ‘sleep hygiene’, and if you are a poor sleeper it would be worth researching this term in more detail.
Key points – How to maintain a healthy brain
1. Ageing changes the brain, but it’s not all bad news. It used to be thought that it was all downhill once you reached your 20s, but it’s now recognised that the brain can continue to grow and adapt into old age.
2. The roots of dementia run deep. Although dementia usually manifests in the elderly, relevant contributing risk factors and biological processes begin to exert an influence much earlier – offering an optimistic opportunity to intervene.
3. Nourish your brain. A healthy diet can help ensure your blood pressure and cholesterol levels are in good shape, which will allow vital nutrients to reach your brain. It also might help dampen inflammation, another risk factor for poor brain health.
4. Train your brain. Completing challenging mental activities will build your ‘cognitive reserve’, which could offer you protection from dementia and cognitive decline.
5. Care for your mental health (and connect with others). Brain health and mental health are deeply intertwined – socialising is one of the most effective ways to protect both.
6. Train your body. Your brain health is also dependent on your overall physical fitness, so aim to exercise regularly.
7. Protect your brain. Blows to the head from injury or even from playing sport can harm your brain and increase your risk of developing dementia, so take care of your grey and white matter.
Navigating diet and supplement controversies
You might have heard of the ketogenic or ‘Keto’ diet, whose proponents (including many celebrities) argue, contrary to my earlier advice, that saturated fat is exactly what we should be eating, at the expense of carbohydrates. So, what to make of this? Well, the weight of the evidence still currently suggests you should include healthy carbs in your diet – wholegrains, legumes, vegetables – and this is my general comment to those asking me about this dietary approach, though I am watching the space carefully.
A main gripe among advocates of the Keto diet is our over-reliance on glucose (sugar) as an energy source, and to a point I agree with them. There’s no doubt that too much sugar is a problem. To put things in perspective, 200 years ago, the average American consumed 2 lbs of the sweet stuff per year according to some estimates. Now, we consume 3 lbs per week! This is largely due to the huge amount of ‘added sugars’ in many people’s diets, such as those found in cakes, candy and in processed foods such as breakfast cereals and table condiments. Some experts refer to Alzheimer’s disease as ‘type 3 diabetes’ highlighting the putative link between chronically high blood sugar and dementia. There is also evidence that, once you have dementia, your brain doesn’t use glucose very well and would be better off relying on ketones, an alternative source of energy derived from fats. Overall, there is no doubt in my mind that our global overconsumption of sugar is killing us, and en route, destroying our brain cells.
You might want to start by aiming for one sugar-free day per week and reward yourself when you have done it (just don’t make the reward unhealthy!). Celebrating the achievement, however small it might seem, is important – it cements the habit. You could then move to having two sugar-free days a few weeks later, and so on.
Vitamin supplements are another source of controversy in the brain health industry. The global vitamin, mineral and supplement industry was worth $48 billion in 2019: there are a lot of people with vested interests in you taking pills to help your brain and body. However, the evidence that these help the brain of an otherwise healthy person who eats well and is not clinically deficient is not compelling, and there is a risk of doing more harm than good. When you receive these vitamins and minerals in your food, they are often packaged with complementary and synergistic compounds that you simply don’t get in a pill. There is even concern that certain antioxidants when given as a supplement might go from being anti-inflammatory to pro-inflammatory, and this is not a good thing for the brain.
The bottom line is I would always advise food over pills, unless recommended otherwise by your doctor. If you really are wedded to the idea of taking some kind of supplement, curcumin (a form of ginger) might be one of the better choices for your brain, and the research also suggests the use of the herbs brahmi (Bacopa monnieri) and Ginkgo biloba might be of some benefit – just don’t rely on them and always be mindful of their potential side-effects.
Understanding genetic risk
I hope I have already convinced you that you are not doomed when it comes to brain health. If you can follow the strategies outlined in this Guide, you can significantly reduce the risk of your general brain function declining. It is better to do this as early in life as possible, but, even if you’re in your autumn years, there are likely to be some benefits.
I have focused so far on modifiable risk factors, but there are some risk factors for dementia that are not changeable and one of the most important is your genes. When I diagnose a patient with a form of dementia, it is common for their adult children to ask me about the chances they too will get it.
The most significant genetic risk comes when you have one or more first-degree relatives with early onset dementia – that is when dementia is diagnosed before the age of 65. Some of these cases are related to specific gene mutations (presenilin 1, presenilin 2 and amyloid precursor protein). If one of your parents carries this mutation (and the other doesn’t), you have a 50 per cent chance of inheriting the gene yourself, and, if you have, you will be at considerably higher risk of developing dementia. Even if you are unfortunate enough to have this genetic vulnerability, however, it makes sense to focus on what you can influence, and I would still recommend all the above measures aimed at reducing modifiable risk factors.
Fortunately, genetic mutations causing early onset dementia are rare. For people with dementia that occurs later in life (ie, after the age of 65, which accounts for 95 per cent of cases of dementia), genetics in general play much less of a role – perhaps no greater than other lifestyle choices that you make. The main gene responsible for this is the apolipoprotein E gene (APOE) and if you have a certain variant (known as APOE4), your risk of dementia will be increased.
What APOE does exactly remains a mystery but it has been implicated in glucose and fat metabolism and this might be relevant. It also seems to influence our inflammatory response, which might be protective in the short term, but might then contribute to the increased risk of dementia later in life. Harking back to our ancestral days once more, most humans likely had the ‘risky’ APOE4 variant because, on balance, it was protective. The world was a lot more septic when our ancestors roamed the plains – the chance of infection was greatly elevated, and of course there were no antibiotics. Therefore, the robust inflammatory response conferred by the APOE4 gene would have meant a greater chance of survival. At the same time, given our ancestors’ short life expectancy, the long-term cost, in terms of risk of dementia, would have been far less of an issue than it is today.
Links & books
Mind Your Brain: The Essential Australian Guide to Dementia (2021) is my own up-to-date and accessible book on how to maintain a healthy brain and manage the challenges that dementia presents. The vast majority of the information will be relevant wherever you reside in the world.
Your Brain In Mind is an evolving website I created to help individuals look after their brain. It includes a link to my soon-to-be released iPhone app for brain optimisation.
The Peter Attia Drive Podcast is a fascinating series that focuses on ‘maximising longevity’, hosted by a Canadian physician who frequently discusses dementia and brain health with his expert guests.
The Centre for Healthy Brain Ageing in Australia also offers an information-packed website, including blogs and educational leaflets, plus one on nutrition and brain health.
The book Supercharge Your Brain (2021) by James Goodwin, the chief scientist at Age UK, is a well-written and engaging account of the evidence behind brain health and how to optimise it.
The book The Brain That Changes Itself (2007) by Norman Doidge is a seminal work on neuroplasticity and how the brain can adapt and heal, despite significant damage.
The book Tiny Habits (2019) by B J Fogg is a very helpful and practical guide to the most powerful intervention we have – good habits.
Editor’s note: the introduction to this Essay was amended on 12 November 2021 to include data on life expectancy and infant mortality.