研究人员称，未来几十年美国痴呆症病例将激增

【中美创新时报2025 年 1 月 14 日编译讯】（记者温友平编译）一项新研究估计，未来 35 年，美国每年患痴呆症的人数将翻一番，到 2060 年每年将达到约 100 万人，而美国黑人每年的新病例数量将增加两倍。《纽约时报》记者帕姆·贝勒克对此作了下述报道。

这一增长主要是由于老龄人口不断增加，因为许多美国人的寿命比前几代人更长。到 2060 年，一些最年轻的婴儿潮一代将年过 90 岁，许多千禧一代将年过 70 岁。高龄是痴呆症的最大风险因素。研究发现，绝大多数痴呆症风险发生在 75 岁以后，随着人们年龄达到 95 岁，风险会进一步增加。

这项研究于周一发表在《自然医学》杂志上，发现 55 岁以上的成年人一生中患痴呆症的风险为 42%。这比之前的终生风险估计要高得多，作者将这一结果归因于有关美国人健康和寿命的最新信息，以及他们的研究人群比之前的研究更加多样化，而之前的研究主要以白人为参与者。

一些专家表示，新的终生风险估计和预计的年度病例增长可能过高，但他们一致认为，未来几十年痴呆症病例将激增。

“即使发病率远低于这一数字，由于美国和世界范围内老年人数量的增长，痴呆症患者数量以及家庭和社会负担仍将大幅增加，”密歇根大学医学教授肯尼斯·兰加博士说，他曾研究过痴呆症风险，但没有参与这项新研究。

痴呆症已经给美国家庭和国家的医疗保健系统带来了巨大的损失。研究发现，目前有超过 600 万美国人患有痴呆症，占 65 岁及以上人口的近 10%。专家表示，在美国，痴呆症每年导致 10 多万人死亡，护理和其他费用超过 6000 亿美元。

纽约大学格罗斯曼医学院最佳老龄化研究所所长、这项研究的负责人 Josef Coresh 博士表示，如果新的预测得到证实，到 2060 年，美国将有大约 1200 万痴呆症患者，这项研究涉及 10 所大学的约 100 名研究人员。

作者和其他专家表示，这项研究强调了预防或减缓痴呆症发作的紧迫性。他们的主要建议是通过药物治疗和生活方式的改变来改善人们的心血管健康；加大力度预防和治疗可能导致痴呆症的中风；并鼓励人们佩戴助听器，这似乎有助于预防痴呆症，因为它可以让人们更多地参与社交和认知活动。

“人们需要看到这个问题的巨大影响，”波士顿大学公共卫生学院生物统计学教授 Alexa Beiser 说，她没有参与这项新研究，但作为该期刊的独立审稿人对其进行了评估。 “这是一个巨大的数字，而且在人群中分布并不均匀，”贝瑟补充道，并指出这项研究发现黑人美国人的风险不成比例。

研究人员评估了一项长期研究的 30 多年数据，该研究针对四个社区的人们健康——马里兰州、密西西比州、明尼苏达州和北卡罗来纳州。科雷什说，15,000 名参与者中约有 27% 是黑人，主要来自密西西比州杰克逊。作者说，这项由美国国立卫生研究院资助的分析侧重于黑人和白人参与者，因为其他种族和族裔群体的参与者并不多。

该研究估计，到 2060 年，黑人中每年新增病例的数量将从 2020 年的约 60,000 例激增至 180,000 例。科雷什说，该人群新增病例增加两倍的主要原因是，黑人美国人活到最高龄的比例增长速度快于白人。

在这项研究中，黑人参与者患痴呆症的平均年龄也比白人参与者要小，而且一生中的风险也更高。

“我不知道我们是否完全理解这一点，但至少一些促成因素是血管风险因素更为常见，” Coresh 说，并指出高血压、糖尿病和高胆固醇会增加痴呆症的风险。他说，研究参与者较低的社会经济地位和教育水平可能也发挥了一定作用，以及影响健康的结构性种族主义。

预测痴呆症风险很复杂，原因有几个。痴呆症的病因各不相同，而且往往不完全清楚。痴呆症的类型也各不相同，而且可能相互重叠。与其他几项研究一样，这项新分析并没有试图估计有多少人会患上最常见的痴呆症类型阿尔茨海默病。这是因为许多专家认为阿尔茨海默病的某些方面可能与血管性痴呆重叠，而且这两种疾病都可能是由心血管问题引起的，Coresh 说。

美国和全球的几项研究发现，近年来老年人痴呆症病例的比例有所下降，这很可能是因为心血管疾病得到了更好的治疗，人口受教育程度也更高，因为教育可以提高大脑的适应力和整体健康状况。

专家和作者表示，这种下降并不与新研究相矛盾，因为这项研究估计了人们一生中累积的痴呆症风险的当前水平，并将其预测到未来。专家表示，积极的变化——例如更健康的行为和对糖尿病和中风等疾病的更好治疗——可能会降低未来几十年任何年龄段的风险率，但由于老年人口的增长，每年的新病例数量仍将从目前的 514,000 例增加。

研究还发现，女性一生患痴呆症的风险高于男性——分别为 48% 和 35%。科雷什说，这主要是因为研究中的女性寿命更长。 “她们在 95 岁生日到来时患痴呆症的风险更高，因为她们中更多的人将活到 95 岁，”他说。

Langa 表示，其他研究人员正在试图了解是否还有生物学差异会增加女性的风险，可能是“体内的激素环境，甚至是潜在的遗传差异，这些差异可能会以不同于男性的方式影响女性的大脑。”

另一个高风险群体是拥有两个基因变体 APOE4 副本的人，这大大增加了患阿尔茨海默病的风险，并且比没有该变体的人更早发病。在这项研究中，拥有两个 APOE4 副本的人一生患痴呆症的风险为 59%，而拥有一个副本的人一生患痴呆症的风险为 48%，没有该变体的人一生患痴呆症的风险为 39%。

本文最初发表在《纽约时报》上。

题图：一项研究表明，55 岁以后，每 10 个成年人中就有 4 个可能患上某种形式的痴呆症。

附原英文报道：

Dementia cases in US will surge in coming decades, researchers say

By Pam Belluck New York Times,Updated January 13, 2025 

After age 55, 4 in 10 adults are likely to develop some form of dementia, according to a study.

The number of people in the United States who develop dementia each year will double over the next 35 years to about 1 million annually by 2060, a new study estimates, and the number of new cases per year among Black Americans will triple.

The increase will primarily be due to the growing aging population, as many Americans are living longer than previous generations. By 2060, some of the youngest baby boomers will be in their 90s and many millennials will be in their 70s. Older age is the biggest risk factor for dementia. The study found that the vast majority of dementia risk occurred after age 75, increasing further as people reached age 95.

The study, published Monday in Nature Medicine, found that adults older than 55 had a 42 percent lifetime risk of developing dementia. That is considerably higher than previous lifetime risk estimates, a result the authors attributed to updated information about Americans’ health and longevity and the fact that their study population was more diverse than that of previous studies, which have had primarily white participants.

Some experts said the new lifetime risk estimate and projected increase in yearly cases could be overly high, but they agreed that dementia cases would soar in the coming decades.

“Even if the rate is significantly lower than that, we’re still going to have a big increase in the number of people and the family and societal burden of dementia because of just the growth in the number of older people, both in the United States and around the world,” said Dr. Kenneth Langa, a professor of medicine at the University of Michigan, who has researched dementia risk and was not involved in the new study.

Dementia already takes an enormous toll on American families and the country’s health care system. More than 6 million Americans currently have dementia, nearly 10 percent of people 65 and older, research has found. Experts say that each year in the United States, dementia causes more than 100,000 deaths and accounts for more than $600 billion in caregiving and other costs.

If the new projections are borne out, there will be about 12 million Americans with dementia in 2060, said Dr. Josef Coresh, director of the Optimal Aging Institute at New York University’s Grossman School of Medicine and a leader of the study, which involved about 100 researchers at 10 universities.

The study reinforces the urgency of trying to prevent or slow the onset of dementia, the authors and other experts said. Their major recommendations are to improve people’s cardiovascular health with medication and lifestyle changes; increase efforts to prevent and treat strokes, which can lead to dementia; and encourage people to wear hearing aids, which appear to help forestall dementia by allowing people to be more social and cognitively engaged.

“One needs to see the huge magnitude of the issue,” said Alexa Beiser, a professor of biostatistics at Boston University School of Public Health, who was not involved in the new study but evaluated it as an independent reviewer for the journal. “It’s enormous, and it’s not equally distributed among people,” Beiser added, noting that the study found disproportionate risk for Black Americans.

The researchers evaluated more than three decades of data from a long-running study of the health of people in four communities — in Maryland, Mississippi, Minnesota, and North Carolina. About 27 percent of the 15,000 participants were Black, primarily from Jackson, Miss., Coresh said. The analysis, which was funded by the National Institutes of Health, focused on Black and white participants because there were not many participants from other racial and ethnic groups, the authors said.

The study estimated that the number of new annual cases among Black people would surge to about 180,000 in 2060 from about 60,000 in 2020. The main reason for the tripling of new cases in that population is that the percentage of Black Americans living to the oldest ages is growing faster than among white people, Coresh said.

In the study, Black participants also developed dementia at younger average ages than white participants and had higher lifetime risk.

“I don’t know that we fully understand it, but at least some of the contributing factors are that the vascular risk factors are more common,” Coresh said, noting that hypertension, diabetes, and high cholesterol increase dementia risk. He said lower socioeconomic status and education levels among the study participants may have also played a role, as well as structural racism that has affected health.

Predicting dementia risk is complicated for several reasons. The causes of dementia vary and are often not completely understood. Types of dementia also vary and can overlap with each other. The new analysis, like several other studies, did not try to estimate how many people would develop Alzheimer’s disease, the most common type of dementia. That is because many experts believe that aspects of Alzheimer’s can overlap with vascular dementia and that both conditions can be fueled by cardiovascular issues, Coresh said.

Several studies in the United States and globally have found the percentage of dementia cases among older adults has declined in recent years, most likely because of better treatment for cardiovascular problems and a more educated population, since education can improve brain resilience and overall health.

That decrease doesn’t contradict the new study, experts and the authors said, because the study estimated the current level of cumulative dementia risk over people’s lifetimes and projected it forward. It’s possible that positive changes — healthier behaviors and better treatment for conditions like diabetes and stroke, for example — could lower the rate of risk at any given age in future decades, but the number of new cases each year will still increase from the current number, 514,000, because of the growing population of older people, experts said.

The study also found that women had a higher lifetime dementia risk than men — 48 percent compared with 35 percent. Coresh said that was primarily because women in the study lived longer. “Their risk of getting dementia by the time their 95th birthday would arrive is higher because more of them will make it closer to their 95th birthday,” he said.

Langa said other researchers were trying to learn whether there might also be biological differences that increase women’s risk, possibly “the hormonal environment in the body or even potential genetic differences that might be affecting women’s brains in different ways than men’s.”

Another high-risk group was people with two copies of the gene variant APOE4, which greatly increases the risk for Alzheimer’s disease and of developing it at younger ages than people without that variant. In the study, people with two copies of APOE4 had a lifetime dementia risk of 59 percent compared with lifetime risks of 48 percent for people with one copy and 39 percent for people without the variant.

This article originally appeared in The New York Times.