The idea of reducing the risk of Alzheimer’s disease through lifestyle changes has been questioned in the past, but there is now more and more evidence that this approach is feasible. This article is organized in a special report from Nature. Figure: The Mediterranean diet rich in olive oil may reduce the risk of Alzheimer’s disease.
Alzheimer’s disease has long been considered a disease associated with aging, and genetic factors are also a risk factor for disease. But there is now growing evidence that lifestyle changes can affect the risk of developing the disease as well as genetic factors.
However, despite the numerous evidences supported over the past few decades, the acceptance of this concept by the entire academic community is still very slow.
For example, at a conference in 2010, the US NIH invited 15 experts in the field of Alzheimer’s disease to discuss the most advanced research progress and consensus in the field of Alzheimer’s disease prevention.
Although there was already very encouraging evidence at the time that lifestyle changes, such as more exercise, more brains, and a healthy diet, could reduce the risk of brain degeneration. For example, a 2006 study tracked more than 2,200 New York City residents for four years, and researchers found that people who insisted on the Mediterranean diet (rich in cereals, fruits, vegetables, fish, and olive oil) were more likely than those who ate meat. People with many dairy products are 40% less likely to develop dementia.
During the three-day meeting, NIH people listened to these cutting-edge research progress. But they ended up not being convinced. They concluded that the evidence at the time was not sufficient to show a causal relationship between lifestyle choices and Alzheimer’s disease, and the research methods used in different studies and the diagnostic consistency of the disease were poor.
NIH people also pointed out other shortcomings in these studies, such as small sample size, long tracking time, and so on. They believe that although there are many potential researches at the time, there is an urgent need for large-scale, well-designed, and long-term randomized trials to determine whether lifestyle differences will affect Alzhai. The risk of morbidity and what lifestyles can have this effect.
Eight years later, observational research and new trials have revolutionized our perception of Alzheimer’s disease. Just three years after the NIH issued their skeptical consensus on the field, 109 scientists from 36 countries jointly submitted a letter to the G8 Dementia Summit in London. They said there was enough evidence to prove that if encouraged. If people are exercising weight control and stopping lifestyle changes such as smoking, then by 2025, about one-fifth of new cases of Alzheimer’s disease will be reduced.
A 2017 study sorted out nine risk factors associated with dementia, including childhood education, middle-aged hypertension, and more. Researchers expect 35% of dementia to be associated with these manageable risk factors. This conclusion also makes these lifestyle-related factors more influential than the genetic risks associated with many genetic variants because of human intervention.
The most powerful evidence for the feasibility of disease prevention comes from epidemiological data. In the past 20 years, the incidence of dementia in high-income countries such as the United States, the United Kingdom, and Canada has fallen by as much as 20%.
There is currently no drug that can effectively prevent the progression of Alzheimer’s disease, and Alzheimer’s disease accounts for two-thirds of dementia, so the treatment of the disease does not explain the decline in the incidence. This phenomenon is more likely to be caused by lifestyle changes in high-income countries.
“If there is a drug that can achieve a similar effect, it is like a god,” said Ull’s psychiatrist Gill Livingston.
The academic community has long believed that cognitive decline is a natural process of aging, and genetic factors can also lead to this increased risk. This view is based on a number of reasonable analyses: older people over the age of 65 are twice as likely to develop Alzheimer’s disease every five years. Moreover, people who carry the APOE ε4 gene mutation are five times more likely to develop the disease than those who do not.
But while the NIH’s attitude toward research in the field was conservative at the time, some researchers at the time had begun to conduct higher-quality studies related to the prevention of Alzheimer’s disease. Since 2010, more and more high-quality research has provided more and stronger evidence for this field.
Especially diet control, diet control is a more controllable risk factor. In a 2013 study, Spanish researchers randomly assigned more than 500 people aged 55 to 80 with high risk of cardiovascular disease to a low-fat diet group or a Mediterranean diet group. The six-year follow-up study found that people who adhered to the Mediterranean diet had higher cognitive function scores.
Recently, some researchers have begun to study how diet affects the brain. Earlier this year, two studies showed that the brains of healthy middle-aged people who adhered to the Mediterranean diet had lower brain atrophy and increased levels of amyloid accumulation compared to the brains of people who did not adhere to the Mediterranean diet. Lower. Lisa Mosconi, a neuroscientist at New York University School of Medicine, said one of the authors of the study: “If you stick to Western eating habits, your brain will age faster, and the Mediterranean diet will have a protective effect.”
The mechanism for this protection is now becoming clearer. Diet may affect the level of inflammation in the brain and oxidative stress. High levels of inflammation and oxidative stress can promote the formation of plaques and tangles in the brain, thereby damaging the brain cells of Alzheimer’s patients.
And because it is now possible to detect signs of disease (such as beta-amylase testing) decades before the onset of disease symptoms, this means that we have a long window of time to intervene in the disease.
But research on whether a particular food or nutrient affects the health of the brain does not lead to consistent conclusions. Although some studies have found that blueberry and grape juice can have protective effects, the relevant data is limited. Studies on fish, omega-3 fatty acids, antioxidants, and vitamins A, B, and C, etc., sometimes lead to the opposite conclusion. The current view is mainly that we should adhere to a multi-diet diet, rather than just eating a certain kind of food to achieve the purpose of preventing disease.
In fact, these studies on diet can also explain the association between Alzheimer’s disease and metabolism or high blood pressure, high blood fat, obesity, type 2 diabetes and other diseases. Because there is growing evidence that diet is also a risk factor for these diseases.
In addition to diet, exercise is also a promising way to improve your brain’s health. In 2011, a meta-analysis of 15 studies involving more than 33,000 people without dementia and a follow-up of up to 12 years found that physical exercise was able to combat cognitive decline. Moreover, animal experiments have also found that exercise can improve memory and reduce the accumulation of beta amyloid plaques.
There are also conflicts in this area. For example, some studies have found that only high-intensity exercise can improve the health of the brain, while others have found that basic anaerobic training is also beneficial to the brain.
And as the research deepens, researchers are beginning to suspect that the protective effect of exercise on the brain is an indirect effect. Exercise can improve obesity or high blood pressure, promote blood flow into the brain, and promote the production of brain-derived neurotrophic factors.
Some of the strongest evidence in this field comes from a study of the association between Alzheimer’s disease and education. The study found that every additional year of education after basic education would have a corresponding benefit.
Although the 2010 NIH consensus argues that educational factors are intertwined with other factors, it is difficult to eliminate these factors, but a 2017 study that analyzed data on more than 55,000 people found that the risk of formal education per year was completed. It will drop accordingly.
Improvements in education (and improvements in health management and living conditions) may explain why the incidence of dementia in high-income countries has declined over the past two decades. Education can promote the formation of new neurons and neural connections, thereby reducing the risk of cognitive decline affecting daily life.
Establishing a cognitive reserve is likely to be able to counter the risk of future cognitive decline, and this can explain some of the evidence that is currently being discovered, such as studies that have found that even with limited school education and enough social interaction, use puzzles Stimulating intelligence, these methods can keep the brain healthy, but in contrast, social isolation is harmful.
In a study in 2017, researchers unexpectedly found that hearing impairment had a greater impact on cognitive health than education. They suspect that hearing can keep the brain active.
In an observational study published last year, researchers also found that people who used hearing aids had a lower risk of developing dementia than people with hearing impairments who did not use hearing aids.
In addition to these factors, marriage seems to be an influencing factor. In a review of 15 studies published last year, researchers found that single people were 42% more likely to have dementia than married people.
As these samples are larger and the number of studies with longer follow-up increases, other risk factors for Alzheimer’s disease are beginning to surface, such as depression and lack of sleep. In fact, a meta-analysis of 27 studies in 2017 found that sleep problems increased the risk of cognitive impairment by 65%, and sleep disorders may explain about 15% of Alzheimer’s disease cases.
Another risk factor is traumatic brain injury (TBI). A study published this year involved nearly 2.8 million people in Denmark with a time span of more than 36 years. Researchers have found that brain damage is associated with an increased risk of dementia, and that this risk increases with the number of TBI increases and the age at which the injury occurs.
Everyone may have already discovered it. In fact, most of the above research conclusions are not inconsistent with the doctor’s advice on maintaining physical and mental health. But to translate these findings into individual individuals, the prevention of Alzheimer’s disease is not as easy as it might seem.
This is partly due to the nuances of these studies. For example, some studies have found that the same lifestyle changes have different or even opposite effects on people of different age groups. Overweight in middle age seems to increase the risk of Alzheimer’s disease, but for people over the age of 60, overweight may have a protective effect on Alzheimer’s disease.
In addition, although cholesterol levels are a very important risk factor for middle-aged people, they are not so important for the elderly.
Therefore, instead of focusing on a single disease prevention strategy, such as only diet control or exercise only, it seems more feasible to use multiple strategies to prevent disease.
From 2009 to 2011, Helsinki researchers assigned 1,200 high-risk populations of 60-77 years old with dementia to diet control, exercise, cognitive function training, and cardiovascular risk management groups, or only routine health advice. Control group.
To the surprise of these researchers, there was an improvement in cognitive function in both groups, presumably because the control group also accepted some suggestions to make positive changes to their lifestyle.
But the researchers found that after two years, the experimental group’s memory and other aspects of the function showed a 25% improvement, and even APOE ε4 carriers can benefit from this intervention. This means that even if there is a genetic risk of Alzheimer’s disease, it does not mean that this group has to sit still and do nothing.
Richard Isaacson established the first Alzheimer’s disease prevention clinic in the United States in 2013. Isaacson and his colleagues collected data from more than 600 people aged 27-96, some of whom already have dementia.
When patients come to the clinic to find ways to reduce the risk of Alzheimer’s disease, they collect information about these people, including blood-related biomarkers, genetic information, lifestyle habits, and cognitive function scores. They will also refer to information on these people’s school education scores, abdominal fat accumulation and the number of dreams during sleep.
Richard Isaacson is communicating with patients
Each participant will be given personalized prevention advice, which may include intermittent fasting, regular exercise or physical training.
In 2016, Isaacson’s team found that these people showed improved brain decision-making and processing speeds just six months after a personalized prevention program. They will soon publish research data from more than 150 people in the New York clinic, and have found that the early results of this study are also very positive.
Based on these efforts, Isaacson suspects that approximately 60% of lifestyle recommendations are common to everyone, such as a Mediterranean diet that seems to benefit everyone. The remaining 40% of the recommendations are very personal, such as treatment for cardiovascular disease, sleep apnea, or specific types of sports.
After 2010, NIH has become more optimistic about the prevention of Alzheimer’s disease. In a 2017 report, NIH staff also acknowledged that significant progress has been made in this area. NIH is currently conducting or supporting research on the effects of cognitive training, blood pressure control, physical exercise and other factors on dementia.
However, in the conclusion of this report, the current evidence is still insufficient, and it is not enough to support the promotion of health campaigns involving the whole people to protect brain health. Although the quality of some of the current evidence is not high enough, more and more people believe that many cases of Alzheimer’s disease can be prevented in advance. There will be more and more solid evidence in this area in the next few years.
“We should have confidence in the prevention of dementia, and it seems that we do have the ability to make some changes.” Livingston said.