Most of us will have heard that lifestyle choices, such as physical activity, diet and sleep, can affect our risk for dementia. Indeed, scientific evidence is quite strong that making the right lifestyle choices can reduce our future risk for dementia by up to 40%.
But how do these lifestyle choices actually reduce our risk for dementia?
Let’s find out.
The failure of most pharmacological intervention studies to treat Alzheimer’s disease has led over the last years to a re-think as to what other factors can modify or reduce our risk for dementia. Revisiting scientific data revealed that many lifestyle factors/choices can have a significant impact on our brain health in ageing and therefore, might also reduce the risk for dementia. Large scale epidemiological studies were conducted and found that indeed certain lifestyle choice increase or decrease our risk for dementia. Many of those lifestyle choices are known risk factors for many age-related brain diseases, such as smoking or drinking excessive alcohol but others, such as physical activity, diet and sleep, were not considered to be as crucial for brain health when we age. However, the scientific analysis found clear evidence that adhering to a healthier lifestyle, including appropriate levels of physical activity, a balanced diet and good sleep hygiene can make a big difference to our brain health when we age, specifically they can reduce our risk for dementia up to 40%.
But how do these factors specifically influence our brain health and reduce our risk for dementia?
The exact pathways on how lifestyle factors influence our brain health are complex but they can be roughly separated into the following aspects:
First off, cardiovascular health. I highlighted in a recent blog post how critical cardiovascular health is for good brain health (see here). If you are interested in more details on how cardiovascular health impacts our brain healthy, I recommend reading that entry. In essence, the health of our blood vessels and our heart is key for our reduction of dementia. Poor blood vessel health can lead to vascular cognitive impairment and in the worst cases vascular dementia, the second most common form of dementia after Alzheimer’s disease. The most common form of poor blood vessel health is caused by either the blood vessels rupturing or being blocked, affecting the provision of oxygen and glucose (sugar) to our brain areas. But also the health of our heart can have a great impact on our brain health. Heart conditions such as atrial fibrillation can significantly affect our brain health by sending blood clots into our brain, potentially blocking blood vessels in the brain. Maintaining good cardiovascular health is therefore critical for healthy ageing and dementia risk reduction. Or to use the common adage: “What’s good for the heart is good for the brain!”.
How can our lifestyle choice improve our cardiovascular?
Besides stopping to smoke and not drinking excessive alcohol, physical activity is THE key factor in having and maintaining good cardiovascular health. Unfortunately, it seems the older we get, the less we move, which means that many of us do not manage to maintain our physical health and in turn develop poorer cardiovascular health. The key physiological benefit of physical activity is that it keeps our blood vessels healthy and therefore reduces the risk of developing brain disease such as dementia. Specifically, physical activity reduces the development of atherosclerosis, which is the build-up of fats due to cholesterol in our arteries. Atherosclerosis can block our arteries causing less oxygen and glucose to reach our brain and affecting its health. The mention of cholesterol highlights that our diet plays also a critical role in cardiovascular health. Eating too much sweet and/or fatty food leads not only to weight gain but also affects directly our cardiovascular health. We know already that too much weight can affect the development of atherosclerosis but it can also affect the development of high blood pressure.
When we gain significant weight, our body needs to supply additional bodyweight with oxygen and glucose via our blood. If we gain this additional weight by physical activity or exercise, our body’s cardiovascular system is at the same time ‘trained’ to supply the additional muscle mass with oxygen and glucose. However, if we gain weight by eating too much, our cardiovascular system never gets trained to supply our additional bulk. Instead, the cardiovascular system takes a shortcut but increasing the blood pressure to supply our additional bodyweight. High blood pressure is a burden of many people when they age and it has also a significant impact on our brain health, as increase blood pressure can lead to blood vessels rupture affecting the oxygen and glucose supply to the brain. Often these blood vessel ruptures do not affect our large arteries but the small ones in the brain, which leads not to symptoms, as a large stroke would do. Such ‘silent’ mini-strokes are very common in ageing and affect our brain health and can lead to vascular cognitive impairment or even vascular dementia.
Since many of us have poor cardiovascular disease when we age, it should come not as a surprise that vascular dementia is the second most common form of dementia, and many people also have mixed dementia, which is a mixture of vascular dementia and Alzheimer’s disease. Maintaining therefore age-appropriate levels of physical activity is key for a healthy ageing approach and I would recommend to anyone that they consult their doctor or nurse to check or improve their physical activity levels.
The next lifestyle factor which is key in reducing our risk for dementia is inflammation. Inflammation is, in essence, a sign that our immune system is activated to heal our body, either by fighting a disease or healing an injury. So, inflammation is a good thing as it shows that our immune system is working and helping our body to heal. However, if inflammation occurs on a long-term basis, so-called chronic inflammation, it can actually weaken our body potentially and increase the disease taking hold of our body. It is literally the case that chronic inflammation is ‘too much of a good thing’, as our immune system goes into overdrive and starts not only attacking potential intruders but also our healthy tissue. So, it is chronic inflammation we need to worry about, not short-term inflammation.
Now, there are several health conditions that cause chronic inflammation, such as arthritis, which is a common age-related chronic inflammatory condition of our joints. It has been known for some time that people with arthritis have also a higher risk of dementia. The reason for this is that the inflammatory processes in the body can also affect the accumulation of proteins in the brain, which can lead to dementia. The exact mechanism of how this works is still being investigated but it has been established that chronic inflammation can ‘fan the fire’ of protein accumulation in the brain, therefore, increasing our risk for dementia. Now, before you worry that you have an increases risk for dementia because of your arthritis, do not worry as long as you take your anti-inflammatory medication for your condition. Indeed, research has shown that people with arthritis on appropriate anti-inflammatory medication do not have an increased in dementia, in fact, they show a reduced risk for dementia since the medication is reducing the chronic inflammation. It is another sign that chronic inflammation plays a significant role in the onset and propagation of dementia by ‘fanning the fire’ of the protein accumulation.
What has this all to do with lifestyle choices?
The key to understand is that we can also develop chronic inflammation as a cause of our lifestyle factors. In particular, if we are overweight or obese our body can see the fat cells we have accumulated as a threat and attack them with our immune system. The longer we are overweight or obese, the longer our body can remain in a state of inflammation, leading to chronic inflammation. This means that if we are long-term overweight or obese, we are likely to have a mild chronic inflammation in our body. This is becoming particularly an issue in Type II Diabetes, a common age-related condition. In Type II Diabetes, people do not produce enough insulin, a hormone created in our pancreas, which regulates our blood sugar levels. People with Type II Diabetes have, therefore, high blood sugar levels, which can damage our tissue and lead to weight gain. In particular, it leads to visceral fat cells, deep in our body, which can lead to some people looking thin but having actually a large amount of visceral fat and having Diabetes Type II. These visceral fat cells emit certain chemicals which can trigger an inflammatory response. This means that if we are having Diabetes Type II, we often have an underlying chronic inflammation and again this increases our risk for dementia significantly.
From the above two sections, it becomes clear that weight gain and I mean fat and not muscle weight gain is not only detrimental to our body’s but also our brain health and influences our risk for developing dementia. But most of these lifestyle factors seems to influence our future risk for dementia more indirectly. How about lifestyle factors that influence protein accumulation for dementia more directly?
There is currently a lot of research ongoing, which investigates in more detail the specific ‘pathways’ to how lifestyle choices influence protein accumulation in different dementias directly. This is not simple as cell biology is complex and many factors might influence the accumulation of the proteins. Still, there is already evidence that one lifestyle factor directly impacts protein accumulation – sleep.
Sleep is something we might easily forget as part of our ‘lifestyle’ but in fact, sleep hygiene has a very important function in our body and brain. Until the 1950s, sleep was considered as the brain simply shutting down and then starting up again when we wake. But we now know that our brain is, in fact, highly active during sleep and goes through specific sleep phases. Some of these sleep phases are important for our memory consolidation, some are important for our dreaming, and some are important to ‘clearing up the mess’ made by our daytime activities. Like a disgruntled parent tidying up the house after the children have gone to bed (I might be slightly projecting here!), our brain ‘clears up’ the mess we have made during our wake time. The clearing up process affects regeneration and repairing specific cells or cell part and it also affects the clearing of proteins from the brain.
Scientific evidence is now quite strong that during specific sleep phases, our brain actively ‘flushes out’ proteins accumulating around our nerve cells. Flushing out in this context means that the accumulated proteins outside of the nerve cells are transported to the corticospinal fluid which transports the excessive proteins away from the brain to be dismantled and recycled. So, our sleep plays an important role in clearing our protein accumulations in the brain.
The flipside of this is that if our sleep is disrupted or irregular, less protein seems to get cleared from the brain, in turn increasing our risk for dementia in the future. Of course, it is well-established that people who have dementia, have disrupted sleep, but it is currently not clear how this impacts protein accumulation. Instead, I am talking here about people who do not have dementia but have an increased risk for dementia because their sleep is disrupted or irregular. For example, conditions such as obstructive sleep apnea (see my blog entry on this here) can affect our sleep and have been shown to affect the clearing of proteins from the brain, therefore increasing our risk for dementia. Obstructive sleep apnea is more common in people who are overweight or obese, showing again how this lifestyle factor not only affects our general health but even the protein clearance in our brain by disrupting the important clearance processes during sleep.
What other sleep disruptions or irregularities can increase our risk for dementia?
The most established one is long-term shift work. Shift work often requires night-time shifts which can really mess up our sleep cycles. I can still remember when I was a paramedic (a lifetime ago) and we had commonly 24hr shifts, which completely disrupted my sleep cycles. Coming home from a shift in the morning, it was very hard for me to sleep and if I slept it was in fits and not long uninterrupted sleep. This is a common observation by many people who have night-shifts. Scientific evidence has shown that long-term shift work increases our risk for dementia, which ironically means that dementia carers, nurses and doctors will also increase their risk for dementia by caring for people with dementia. Now we should know that this increased risk for dementia due to disrupted sleep is because the clearance processes of the proteins are disrupted and the more protein accumulates, the higher risk for dementia.
Taken together, there is increasing evidence that lifestyle choices/factors play a significant role in our future risk for dementia. In turn, scientific evidence shows that we can reduce our risk of dementia by up to 40% if we make the right lifestyle choices. Obviously, we should not blame or shame people for making the ‘wrong’ lifestyle choices, instead, it demonstrates that we can make a difference to our future dementia risk by the lifestyle decisions we make now.
Hopefully, by the end of this article, you will know more as to how our lifestyle choices/factors specifically reduce our risk of dementia in the future. Just to say that I selected specific examples for this article and there are several other lifestyle factors out there that we can potentially modify to reduce our risk for dementia but you would do very well already to eat healthily, sleep well and move more.