Some evidence-based natural strategies are being researched for preventing Alzheimer’s disease, but there’s no strong evidence to recommend any single intervention. Read on to learn about the evidence behind lifestyle and supplements that are hypothesized to reduce the risk of Alzheimer’s and support your brain health.
Alzheimer’s Disease Prevention: Does it Exist?
Possible Causes and Course of Alzheimer’s
There is currently no known cure for Alzheimer’s disease (AD).
Alzheimer’s disease is complex and scientists are still trying to understand its causes and course. The disease is described as progressive, which means that it gradually gains force to and destroys brain function, causing severe memory loss [1].
Being diagnosed with Alzheimer’s disease changes a person’s life. It requires careful medical monitoring and treatment, as well as a safe and supportive environment.
How Much Do We Know About Prevention?
Scientists are investigating whether any natural strategies can help prevent Alzheimer’s disease. Experiments are still in the early stages and we’ve outlined the existing research efforts in this article for informational purposes.
According to the National Center for Complementary and Alternative Medicine (NCCIH) [2]:
“Currently, there is no strong evidence that any complementary health approach or diet can prevent cognitive impairment.”
Therefore, there is no proven way to prevent Alzheimer’s disease or dementia.
Nonetheless, we have solid evidence that some factors associated with leading a healthy lifestyle may play a role in reducing the risk of these diseases. But more research is needed before these approaches are proven to be effective for Alzheimer’s disease prevention.
The Modern Lifestyle Hypothesis
Though Alzheimer’s is commonly diagnosed in people over 65 years old, many people nowadays start to experience signs of cognitive decline at a much younger age.
For this reason, Alzheimer’s is now being reframed by some scientists as a disease of the modern, sedentary, unhealthy lifestyle – much like obesity and type 2 diabetes. This stance is still experimental, however [3].
Nonetheless, based on this theory, scientists speculate that the type of lifestyle someone leads can have a large impact on brain health.
They say that just as people are told to watch their intake of salt and saturated fats to reduce heart disease risk, so they may need to be told to supply their brain the nutrients it needs to work at its best.
This way, people would be shifting their “brain environment” to one that might theoretically offset Alzheimer’s and other neurodegenerative diseases.
No clinical evidence backs up this hypothesis, though.
On the other hand, there’s evidence that type 2 diabetes and heart disease are strongly linked to the development of Alzheimer’s disease. These chronic diseases can be prevented by eating a healthy diet and exercising. By lowering your risk of one chronic disease, you might also lower your risk of many others – killing two birds with one stone [4, 5, 6, 7].
The Right Time for Prevention?
The right time for Alzheimer’s disease prevention is as soon as possible, if a healthy lifestyle is taken to mean prevention. It’s never too early to establish healthy habits.
Small brain changes in Alzheimer’s disease occur 20 years before people experience the first symptoms. Scientists hypothesize that it might be at this stage – or before – that lifestyle choices might have the biggest impact. More research is needed to determine this, however [1].
When to See a Doctor
If your goal is to improve your brain health to deal with your cognitive issues – including those of poor memory, forgetfulness, or personality changes – it’s important to talk to your doctor, especially your symptoms are significantly impacting your daily life.
Major memory and behavior changes – such as forgetting recent events or conversations, misplacing your possessions, getting lost in familiar places, having trouble finding the right words to describe something, and low mood or apathy – are all reasons to see a doctor.
Many conditions, some of which are treatable, can result in poor memory or other symptoms of cognitive impairment or dementia.
Your doctor should diagnose and treat the condition causing your symptoms.
Likewise, if you are concerned about the symptoms of someone close to you, talk to them about scheduling a doctor’s appointment and going there together.
Many people with cognitive decline are not fully aware of their own memory and behavior, and the support of loved ones can be indispensable.
Precautions
Remember, changes in brain chemistry are not something that people can change on their own with the approaches listed below. Instead, the factors listed here are meant to support overall brain health and well-being.
The main idea is that living a healthy lifestyle, eating nutritious foods, getting quality sleep, and engaging in exercise is critical for maintaining a healthy brain – and sharp memory – as we age [4, 5, 6, 7].
You may try the additional strategies listed below if you and your doctor determine that they could be appropriate.
Read through the approaches listed here and discuss them with your doctor before trying them out. None of these strategies should ever be done in place of what your doctor recommends or prescribes.
Have in mind that supplements have not been approved by the FDA for medical use or Alzheimer’s disease prevention. Supplements generally lack solid clinical research. Regulations set manufacturing standards for them but don’t guarantee that they’re safe or effective.
Lastly, supplement-drug interactions can be dangerous and, in rare cases, even life-threatening. That’s why it’s so important to consult your doctor before supplementing and let them know about all drugs and supplements you are using or considering.
Complementary Approaches Researched for Alzheimer’s Disease Prevention
Likely Effective:
1) Regular Exercise
Studies show that exercise is one of the most important ways to support brain health. It has been hypothesized to prevent or improve dementia and Alzheimer’s disease. Exercise may improve brain blood flow and potentially increase the size of the hippocampus (the brain’s memory center) and stimulate the birth of new brain cells [8, 9, 10].
A review study involving more than 160k people suggested that physical exercise may cut the risk of developing Alzheimer’s disease in half [3, 11, 12].
Moderate aerobic exercise or cardio seems to be good for reducing the risk of cognitive impairment and dementia that comes with aging, according to some evidence. But even strength training appears to work well, according to some studies [3, 11, 12].
2) Heart-Healthy Diets
Some evidence suggests that a heart-healthy diet may also help protect the brain. This does not have to mean following any specific diet. A heart-healthy diet is typically described as one that limits the intake of sugar and unhealthy fats and places emphasis on eating plenty of fruits, vegetables, and whole grains.
Two diets of this type are commonly mentioned: the Mediterranean diet and the DASH diet.
The DASH Diet Controversy
The DASH (Dietary Approaches to Stop Hypertension) diet highlights vegetables, fruits, and fat-free or low-fat dairy products. It includes whole grains, fish, poultry, beans, seeds, nuts, and vegetable oils; it limits sodium, sweets, sugary beverages, and red meats.
The main issue with the DASH diet is that recent studies go against some of its core features. For one, the DASH diet emphasizes low-fat or fat-free foods. Strong evidence now suggests that olive oil, omega-3 fatty acids, and some other types of fat are healthy and good for the heart [13, 14, 15].
What’s more, recent studies suggest that ill-famed saturated fats should also be part of a healthy diet – in moderation. One scientist concluded that “saturated fat is not the villain we once thought it was.” [16]
This goes to say that we have probably much more to learn about different types of fat and their impact on heart and brain health. But what we do know so far is that no good evidence supports avoiding fats altogether in most people.
Additionally, some people don’t tolerate legumes and may have a hard time staying on the DASH diet.
To add another layer of complexity, even people who don’t have food intolerances struggle to follow this diet in a healthy way.
If you just replace oil with a low-fat fast food (that may also be higher in salt, sugar, and/or additives), you are not doing this diet right. It was meant to – and studied in the scenario of – replacing fats with vegetables, fruits, and other healthy high-fiber whole foods [17].
Lastly, most studies compared the DASH diet to a typical American diet, which includes mainly unhealthy processed foods in large quantities. Therefore, there’s no evidence that the DASH diet is better than other healthy diets that provide balanced amounts of nutrients and energy.
All in all, many inconsistencies surround this diet, typically recommended by the American Heart Association (AHA). Future scientific reviews should take these nuances in mind to determine its true value in preventing heart disease in the general population.
Therefore, we’ll mainly focus on the Mediterranean diet in this post.
The Meditteranean Diet
The Mediterranean diet consists of foods that cultures surrounding the Mediterranean sea traditionally eat. It abounds in fruits, vegetables, olive oil, and seafood.
The MIND diet is a modified version of the standard protocol that emphasizes brain-healthy foods.
Following the Mediterranean diet can significantly reduce the risk of Alzheimer’s disease, according to review studies. It also was also associated with a reduced risk of dying from the disease in some studies [18, 19, 20, 21].
In a study of 278 older people, brain scans revealed that those who followed the Mediterranean diet had lower levels of beta-amyloid protein in their brains [22].
The Mediterranean diet is rich in olive oil, which has been hypothesized to help prevent Alzheimer’s. However, clinical data are lacking.
In a mouse study, olive oil improved memory and stimulated the creation of new cells in the hippocampus. In another mouse study, olive oil increased enzymes that clear beta-amyloid and tau proteins in the brain [23, 24].
The Mediterranean diet is also rich in fruits and vegetables: good sources of potassium. Higher intakes of potassium may help prevent the onset of Alzheimer’s disease, according to one theory that has yet to be clinically verified [25].
Increased potassium intake reduced beta-amyloid in brain tissues, improved cognitive performance, and decreased markers of inflammation and oxidative stress in a study on mice [25].
Insufficient Evidence for:
3) Get Enough Sleep
Scientists say that, when we are awake, waste products such as beta-amyloid proteins naturally accumulate in the brain. During sleep, the brain clears these waste products. But when sleep is diminished or disturbed, the waste products can accumulate and cause damage to neurons. In the long run, this can lead to cognitive impairment and dementia, including Alzheimer’s disease [26].
While plausible, this theory has yet to be confirmed in large and properly-designed human studies. Nonetheless, getting quality sleep on a regular basis undoubtedly supports brain health and general wellness.
One review of observational studies including nearly 250k people revealed that those with sleep disturbances had an increased risk of developing dementia [27].
Studies in both humans and animals have shown that sleep deprivation or disturbance is linked with increased beta-amyloid and tau protein in the brain. What’s worse, as more of these waste products build up, they disrupt the sleep-wake cycle and fragment sleep. This might create a vicious cycle in which poor sleep worsens Alzheimer’s, and Alzheimer’s worsens sleep [28, 29, 30].
If you have sleep problems, read through this list of science-based sleep-hacking tips.
4) Stop Smoking
There’s been a lot of controversy about whether cigarette smoking increases or decreases Alzheimer’s risk. According to the latest research, smoking greatly increases the risk. It triggers oxidative stress in the brain and damages brain cells [31].
If you are a smoker, you can reduce your risk of developing Alzheimer’s disease in half by stopping in time. According to an observational study of more than 20k people, smoking increases the risk of Alzheimer’s by more than 100%. Smoking during midlife (40-55 years old) is particularly damaging to the brain [32].
Possibly Effective:
5) Education & Studying
According to some evidence, people with higher education levels (and higher income) have a lower risk of developing AD. One theory attempts to explain this association by claiming that your years of studying can build your cognitive reserves [33, 34, 35].
Just as the term suggests, your cognitive reserves reflect your mental capacities. You need to “put in” to your cognitive reserves throughout your life.
As you study new topics and acquire complex knowledge, sets of connections are strengthened between neurons in your brain. Strong and diverse connections are thought to make people more resilient to cognitive decline [33, 34, 35].
When connections are lost during the progression of Alzheimer’s disease, the brain might be able to compensate with alternate routes of communication built during the years of study [33, 34, 35].
This doesn’t mean that you should enroll in a college program or start a Ph.D. Nor does it mean your cognitive reserves are low if you didn’t get an advanced degree in school.
Your cognitive reserves depend on how much time you spent studying in your life. This usually correlates with years spent in school, but it doesn’t have to.
If you prefer to study by yourself – and are persistent about it – you can probably build your cognitive reserves as much as someone completing a university-level degree.
6) Social and Mental Activity
Keeping your brain as active as possible through mentally stimulating activities, especially later in life, is also hypothesized to help keep Alzheimer’s disease at bay.
Researchers say that mental activity may help prevent or delay the onset of dementia and other cognitive disorders that come with aging. Research suggests that stimulating the brain this way might increase connections between brain cells, the size of the brain, and the health of white matter (which sort of works to “tie” brain cells together) [36, 37].
Reading, playing games, doing puzzles or even dancing are great for helping elderly people stay sharp. Some scientists say we should think of the brain as a muscle and apply the “use it or lose it” principle to maintain its health [38, 39].
7) Reduce Stress
Chronic stress might contribute to the development and progression of Alzheimer’s disease. It also likely contributes to many chronic diseases, including heart disease, and worsens mental health in the long run [40].
Mice studies show that corticotropin-releasing hormone (CRH), released from the pituitary gland as part of the stress response, stimulates the production of beta-amyloid proteins [41, 42].
The stress hormone cortisol might be equally harmful, according to animal experiments. In mice studies, cortisol stimulates the accumulation of both beta-amyloid and tau proteins [43, 42].
Read about factors that may inhibit the stress response and reduce cortisol in this post.
8) Protect Your Head
A systematic review of studies involving more than 2 million people revealed that head injury increases the risk of Alzheimer’s disease by 50% and the risk of any type of dementia by more than 60% [44].
Your choice of profession may also influence your risk of head injury and Alzheimer’s disease. People who experience recurrent head injuries due to their profession, such as football players, are four times more likely to develop a neurodegenerative disorder [45].
Insufficient Evidence:
The following substances and lifestyle changes have shown promise for Alzheimer’s disease prevention in limited, low-quality clinical studies.
There is currently insufficient evidence to support the use of the approaches listed below for Alzheimer’s disease prevention, and they should never replace what your doctor prescribes.
9) Vitamin D
Getting more sun or taking a vitamin D supplement has been researched for reducing the risk of Alzheimer’s disease, but no solid evidence is available [46, 47].
A review study revealed that Alzheimer’s disease patients have lower levels of vitamin D, compared to healthy people. Another review including nearly 10k people found that blood levels of vitamin D less than 50 nmol/L were associated with a higher risk of AD and dementia [46, 47].
A trial of 52 people suggested that vitamin D reduced beta-amyloid deposits and improved cognitive function, but only in those with mild cognitive impairment which precedes Alzheimer’s disease. Patients with early Alzheimer’s disease did not experience improvement [48].
Scientists are also using cell studies to explore if vitamin D stimulates immune cells to break down beta-amyloid deposits in the brain. At the same time, vitamin D is hypothesized to protect healthy brain cells against damage from beta-amyloid proteins, but this remains clinically unverified [49, 50].
10) Polyphenols
Despite some promising findings, no solid evidence is available to support the use of polyphenols for Alzheimer’s prevention.
Mild cognitive impairment is considered a precursor state to full-blown dementia and Alzheimer’s disease. A trial of 85 people found that those with mild cognitive impairment had lower levels of antioxidants, similar to what is seen in Alzheimer’s. Whether increasing the body’s antioxidant levels early helps prevent Alzheimer’s is unknown, though [51].
Sirtuin 1 is an enzyme that protects against age-related diseases like Alzheimer’s. It is controlled by the SIRT1 gene. Studies have focused on increasing the activity of the SIRT1, as it is hypothesized to reduce the conversion of amyloid precursor protein to beta-amyloid proteins based on mouse models of Alzheimer’s [52, 53].
The protein NF-κB is proposed to be a key mediator of aging. It is activated by toxic, oxidative, and inflammatory stressors. In mice studies, inhibition of NF-κB leads to later onset of age-related symptoms and disorders [54].
The following polyphenols are being researched for preventing age-related cell damage caused by reactive oxygen species through increasing the activity of SIRT1 [55, 56]:
Human data are lacking.
Scientists are investigating whether these compounds can reduce the formation of beta-amyloid deposits and improve communication between cells in test tubes [55, 56].
11) Manganese
A meta-analysis (17 studies, 2,090 subjects) suggested that patients with Alzheimer’s have reduced blood manganese levels. However, this was an association study only, and one that has not yet been replicated. Therefore, we can’t know if getting enough manganese may help prevent Alzheimer’s until proper human studies are carried out [57].
Based on cellular research, some scientists are looking to determine if manganese deficiency can cause mitochondrial dysfunction and increase glutamate in the brain. These are both associated with Alzheimer’s disease, but future animal and human experiments would need to verify this link [58].
The link between HSV and Alzheimer’s is still controversial and largely unconfirmed.
According to an observational study of more than 30k people in Taiwan, participants carrying the herpes simplex virus (HSV) had an almost 3-fold risk of developing dementia. The study also found that those taking antivirals such as acyclovir had a 90% reduced risk compared to those who did not [59].
This study has several limitations and its findings have not yet been replicated.
Other lines of evidence now point to the fact that people carrying the ApoE4 gene variant seem to be much more vulnerable to the effects of HSV. Carriers of ApoE4 experience more frequent reactivations of the virus, and suffer higher levels of inflammation and cell damage [60].
Scientists are also investigating whether the accumulation of beta-amyloid and tau proteins occurs in HSV infected cells in test tubes and whether HSV DNA is found in beta-amyloid deposits [60].
Having several trajectories of intriguing findings in mind, the NIH recently announced that it is funding high-priority research to better determine the relationship between microbial infections and Alzheimer’s disease [61].
Takeaway
There is no guaranteed way to prevent Alzheimer’s disease.
The main idea is that living a healthy lifestyle, eating nutritious foods, getting enough quality sleep, quitting smoking, and engaging in plenty of physical activity is critical to maintaining a healthy brain as you age. Engaging in mentally and socially stimulating activities might also help.
