好英语网你有多大几率患上阿兹海默症？
The actor Chris Hemsworth announced last week that he’s taking a break from acting to focus on his health. The news came after Mr. Hemsworth learned through genetic testing that he has two copies of the APOE4 gene variant, which is associated with increased odds of developing Alzheimer’s disease, the most common form of dementia. The 39-year-old star of “Thor” has not reported having any symptoms, but he told Vanity Fair that he wanted to focus on mitigating his risk as much as possible.
演员克里斯·海姆斯沃斯上周宣布，他将暂时息影，专注自身健康。此前，海姆斯沃斯通过基因检测了解到，他携带有两个APOE4基因变体的副本，这种变体与患阿尔茨海默病的几率增加有关。阿尔茨海默病是最常见的一种失智症。这位39岁的“雷神”称自己没有出现任何症状，但他告诉《名利场》，他想要专注于尽可能地降低风险。
Should you, like Mr. Hemsworth, undergo genetic testing to assess your risk for Alzheimer’s? And if you have the variant, what options are available to prevent or delay the condition? Here’s what to know.
你应该像海姆斯沃斯一样，通过基因检测来评估自己患阿尔茨海默病的风险吗？如果你携带这种变体，有什么方法可以预防或延缓这种情况？以下是你需要知道的。
What is APOE4?
APOE4是什么？
The APOE gene is important for the formation of a protein that helps carry cholesterol through the bloodstream. Nearly 30 years ago, scientists learned that APOE also influences a person’s chances of developing Alzheimer’s.
APOE4基因对帮助在血液中运输胆固醇的蛋白质的形成很重要。近30年前，科学家们了解到，APOE还会影响一个人患阿尔茨海默病的几率。
There are three variants of the gene, each conferring a different risk. People with the APOE2 variant appear to have a decreased risk of Alzheimer’s; the APOE3 variant — the most common type — is “neutral,” meaning it does not increase or decrease risk; and the APOE4 variant raises a person’s risk. Everyone has two versions of the gene, one inherited from their mother and one from their father.
这一基因有三种变体，分别意味着不同程度的风险。携带APOE2变体的人患阿尔茨海默病的风险似乎较低；最常见的类型APOE3变体是“中性的”，这意味着它不会增加或减少风险；APOE4变体则会增加患病风险。每个人都有两种此类基因，一种遗传自母亲，另一种遗传自父亲。
About 25 percent of people carry one APOE4, increasing their chance of developing Alzheimer’s by two or three times. Another 2 to 3 percent of people have two copies of APOE4, as Mr. Hemsworth does. This is associated with a roughly 10-fold higher risk. Having APOE4 is also linked to earlier onset of the disease.
大约25%的人携带一个APOE4基因，这将使他们患阿尔茨海默病的几率增加两到三倍。还有2%到3%的人像海姆斯沃斯一样携带两个APOE4基因副本，这将可能使风险升至大约10倍。携带APOE4也与疾病的早期发作有关。
Scientists aren’t exactly sure why a gene involved in capturing cholesterol plays such a large role in Alzheimer’s disease. It’s possible that changes in cholesterol can damage brain cells or cause inflammation in the brain, which could lead to dementia.
科学家们还不完全确定为什么一种与捕获胆固醇有关的基因会在阿尔茨海默病中扮演如此重要的角色。有可能是因为胆固醇的变化会损害脑细胞或引起大脑炎症，从而导致失智症。
Having the APOE4 gene variant, either one or two copies, does not mean you will definitely get Alzheimer’s disease. Some conditions, such as Huntington’s disease, are directly caused by a specific gene mutation. Alzheimer’s disease and APOE4 don’t work like that. The gene is just one factor that contributes to people’s risk. Some people with the gene variant are never diagnosed with the disease, and many people without APOE4 develop Alzheimer’s.
携带APOE4基因变种，无论是一个或两个副本，并不意味着你一定会得阿尔茨海默病。有些疾病是由特定的基因突变直接引起的，如亨廷顿舞蹈症。但阿尔茨海默病和APOE4不是这样运作的。这种基因只是导致人们存在患病风险的因素之一。一些携带这种基因变异的人从未被诊断出患有这种疾病，而许多没有APOE4的人会患上阿尔茨海默病。
How do you know if you have the APOE4 variant?
如何得知自己带有APOE4变异？
If you’re interested in knowing your status, you can ask your doctor or a genetic counselor about getting tested. You can also order a kit directly from 23andMe, which includes APOE4 on its health panel. However, Alzheimer’s experts are divided about whether testing for the gene is helpful for most people.
如果你想知道自己的情况，可以向医生或基因顾问咨询做检查。你也可以直接从23andMe订购套餐，其健康面板上有APOE4选项。然而，阿尔茨海默病专家在基因检测是否对大多数人有帮助的问题上存在分歧。
“Generally, in my clinical practice, I dissuade people from getting the test and getting the information,” said Dr. Gary Small, chair of psychiatry at Hackensack University Medical Center in New Jersey. If you have a family history of dementia, you should assume you have an increased risk, he said, “so getting the genetic test is not going to tell you much more.”
新泽西州哈肯萨克大学医学中心精神病学主任加里·斯莫尔医生表示：“一般来说，在我的临床实践中，我劝人们不要去做检测，不要去获取相关信息。”他说，如果你有失智家族史，你就应该假设自己的风险会增加，“所以做基因检测不会告诉你更多。”
Dr. Richard Isaacson, an adjunct associate professor of neurology at Weill Cornell Medical College, disagreed. “The reason that I believe in testing for APOE4 is that some people really want to know more about themselves, and it really democratizes the ability to learn about those risks,” he said. “Not about if they’re going to get the disease, but what we can do about it.”
威尔·康奈尔医学院神经学兼职副教授理查德·艾萨克森不同意这种观点。“我相信进行APOE4检测的原因是，有些人确实希望更了解自己，这确实能让了解这些风险的能力大众化，”他说。“不是关于他们是否会得这种病，而是关于我们能做些什么。”
If you do decide to get tested, Margaret Pericak-Vance, director of the John P. Hussman Institute for Human Genomics at the University of Miami Miller School of Medicine, said she would “suggest having a meeting with a genetic counselor afterward, because the risk is not straightforward.”
如果你决定进行检测，迈阿密大学米勒医学院约翰·P·胡斯曼人类基因组学研究所主任玛格丽特·佩里亚克-万斯说，她会“建议你在检测后与基因顾问会面，因为风险并不是那么简单直白的。”
“By having one copy or two copies, it gives you an important part of the picture, but it’s just one part of a very complex risk picture,” Dr. Isaacson said. “Genes are not your destiny. You can win the tug of war against your genes.”
“有了一两个副本，你就能看到这幅图景的重要部分，但这只是非常复杂的风险图景的一部分，”艾萨克森说。“基因不等于命运。你可以赢得与基因的拉锯战。”
How can you reduce your chance of getting Alzheimer’s?
如何降低患阿尔茨海默病的几率？
All the experts interviewed for this article agreed that regardless of your genetic status, it is possible to reduce your overall risk of dementia, including Alzheimer’s. Studies show that tried and true healthy habits — exercise, eating well, limiting your alcohol intake, getting enough sleep, not smoking and being socially engaged — are key to fending off neurodegenerative disease.
为这篇文章接受采访的所有专家都同意，无论基因状况如何，罹患失智（含阿尔茨海默病）的总体风险都是有可能降低的。研究表明，久经考验的真正健康习惯——锻炼、健康饮食、限制酒精摄入、充足睡眠、不吸烟和参加社交活动——是抵御神经退行性疾病的关键。
Exercise, both endurance and strength training, helps the brain grow new connections between cells, particularly in the hippocampus, an area important for memory. Scientists think that building up more connections can be protective against memory loss. Dr. Small said that if you have the APOE4 variant, “physical exercise still can be helpful. There’s some studies showing that may even be more helpful for people with a genetic risk.”
锻炼，包括耐力和力量训练，有助于大脑细胞之间建立新的连接，特别是在对于记忆很重要的海马体当中。科学家们认为建立更多的连接可以防止记忆丧失。斯莫尔说，如果你带有APOE4变异，“体育锻炼仍然是有帮助的。一些研究表明，这甚至可能对有遗传风险的人更有帮助。”
There’s also evidence that a healthy diet, such as the Mediterranean diet, can be beneficial. In particular, it helps to eat fruits and vegetables, which are high in antioxidants, and fish, which contain omega-3 fats that can reduce inflammation. “These kinds of diets can have a tremendous effect on brain health,” Dr. Small said.
也有证据表明，地中海饮食等健康饮食是有益的。特别是多吃富含抗氧化剂的水果和蔬菜，以及含有omega-3脂肪酸的鱼类，有助于减少炎症。“这类饮食可以对大脑健康产生巨大影响，”斯莫尔说。
While the importance of vitamins and healthy fats in your diet is clear, the case for taking supplements for brain health is weak. Dr. Isaacson said that a person’s genes may play a role in whether supplements can be beneficial. For example, research suggests that people with two copies of APOE4 can’t absorb omega-3 fats from their diet as well as people without the genetic variant. Taking an omega-3 supplement may be advantageous for that specific group of people, but likely isn’t helpful for others, he said.
虽然维生素和健康脂肪在饮食中的重要性显而易见，但为了大脑健康而服用补充剂的理由并不充分。艾萨克森说，一个人的基因可能会在补充剂是否有益的问题上发挥作用。例如，研究表明，带有两个APOE4基因副本的人不能像没有这种基因变异的人一样从饮食中吸收omega-3脂肪酸。他说，服用omega-3补充剂可能对特定人群有利，但对其他人可能没有帮助。
Finally, higher education has consistently been shown to be one of the best ways to lower a person’s risk for dementia. The hypothesis is that education helps people’s brains become more resilient, a concept known as cognitive reserve. Even if there are visible changes to a person’s brain, the more education they have, the less likely they are to display dementia symptoms. “If you look at numerous studies, level of education is correlated with lower risk, even within families,” Dr. Pericak-Vance said. “It all has to do with cognitive reserve. You build up more cognitive reserve the more schooling you get.”
最后，高等教育始终是降低失智风险的最佳方式之一。据推测这是因为教育有助于让人的大脑更加灵活，也就是一种称为认知储备的概念。即便一个人的大脑出现明显的变化，受教育程度越高，就越少显现失智症状。“你去看许多的研究，教育水平和较低的风险是有关联的，即便在家族内都是如此，”佩里亚克-万斯说。“这些都跟认知储备有关。受教育越多，认知储备就越多。”
Studies on identical twins, who share nearly all the same genes, have shown just how much lifestyle behaviors influence brain health. In one of the largest studies of its kind, which looked at 392 pairs of twins aged 65 and up where one or both had Alzheimer’s disease, genes accounted for 58 percent of a person’s risk. The rest depended on lifestyle and environmental factors.
对基因几乎相同的双胞胎的研究显示，生活方式对脑健康有很大影响。在此类研究中规模最大的一项，对392对年龄在65岁以上的双胞胎进行了研究，这些双胞胎中至少有一人患有阿尔茨海默病，基因在一个人的风险中占了58%。其它的取决于生活方式和环境因素。
Who else is at risk for developing Alzheimer’s?
还有哪些人存在阿尔茨海默病风险？
Age is the number one risk factor for Alzheimer’s disease. As we get older, chronic diseases associated with aging — such as high blood pressure, high cholesterol and diabetes — start to take their toll on the brain as well as the body.
年龄是阿尔茨海默病的头号风险因素。随着年龄的增长，一些跟衰老有关的慢性病——例如高血压、高胆固醇和糖尿病——在摧残身体的同时，也在破坏大脑。
Women are more likely than men to get Alzheimer’s, for multiple possible reasons. Women generally live longer than men, so they might have more time to develop the condition. Historically, women did not receive as much education as men, which experts surmise could have increased the risk for earlier generations. There also appears to be an interplay between the loss of estrogen during menopause and Alzheimer’s; research is ongoing into whether hormone replacement therapy could be beneficial.
女性比男性更容易患上阿尔茨海默病，可能的原因有许多。女性一般比男性长寿，可能有更多时间产生这些问题。从历史上看，女性受教育程度不及男性，专家推测这可能在过去导致风险的增加。另外更年期的雌激素损失和阿尔茨海默病之间可能存在相互影响；目前有人在研究荷尔蒙置换疗法会不会有帮助。
Black and Latino Americans also have an elevated risk for Alzheimer’s — two- and 1.5-times higher than white Americans. One recent study found that the brains of Black Americans aged faster than white Americans’ brains, with more neurodegeneration at an earlier age, which could contribute to risk of disease. The authors theorize that one reason for these disparities is the additional stress Black and Latino Americans experience because of systemic racism.
黑人和拉丁裔美国人的阿尔茨海默病风险也偏高——比白人高出1.5到2倍。近期一项研究发现黑人大脑衰老比白人快，更早出现神经退化，这可能跟阿尔茨海默病风险增加有关。研究作者提出这种差异的一个原因是系统性种族歧视给黑人和拉丁裔美国人造成额外的压力。
Race also appears to play a role in the risk associated with the APOE4 variant. People of Asian descent have the greatest increased risk of developing Alzheimer’s if they have APOE4, while people of African descent with APOE4 have the lowest elevated risk. Dr. Pericak-Vance said this is likely because of differences in the DNA that surrounds the APOE gene and influences how it acts.
种族在APOE4变体相关风险中似乎也起到一定作用。APOE4给亚裔造成的阿尔茨海默病风险增加是最大的，非裔最少。佩里亚克-万斯说这可能是由于围绕APOE基因的DNA差异，以及其行为的影响。
If you think you have an elevated risk of Alzheimer’s, either because of your genes or other factors, Dr. Isaacson recommended talking to your doctor sooner rather than later. And regardless of your individual risk, everyone can benefit from incorporating more healthy habits, he said. “It’s almost never too early, in my opinion, to adopt brain-healthy choices.”
如果你认为你的阿尔茨海默病风险格外高，无论是因为基因还是别的什么因素，艾萨克森建议尽快去咨询你的医生。他说，无论个人风险如何，建立更健康的习惯总是有益的。“在我看来，应尽早做出有利脑健康的选择，多早都不算早。”