It might seem like someone with Alzheimer’s disease or another form of dementia wakes up one morning and suddenly struggles to remember important information. But scientists know that what precedes² those first memory symptoms is more complex.
人们往往以为，阿尔茨海默病或其他类型痴呆症患者，会在某天清晨醒来后突然记不住重要事情。但科学家发现，在初期记忆障碍症状出现之前，病情的演变过程远比想象中复杂。
As long as a decade before memory impairment appears, tendrils of the disease are already subtly taking hold. During this time, “a lot of people have no obvious cognitive symptoms, but, actually, brain changes are occurring³,” says Yuan Zhang, a social-medical scientist who researches the condition at Columbia University. These changes may even precede the amyloid plaques, detected in imaging tests, that are a known hallmark of Alzheimer’s.
早在记忆损伤症状出现的十年前，这种疾病就已悄然开始侵蚀人体。任职于哥伦比亚大学、专攻该病症研究的社会医学科学家张媛表示：“这个阶段里，很多人没有明显的认知异常，但大脑其实已经发生了病变。” 这类脑部变化，甚至会早于影像检查可发现的淀粉样斑块 —— 而淀粉样斑块是阿尔茨海默病公认的典型特征。
With an estimated⁴ 6 million Americans currently experiencing some form of dementia and twice that number expected as the population ages, scientists are urgently focusing on these less visible changes.
据估算，目前美国有600万人患有各类痴呆症。随着人口老龄化加剧，这一数字预计将会翻倍，因此科研人员正全力研究这些不易察觉的身体变化。
Some are exploring brain imaging and gut biopsies for other markers that might reveal earlier dementia signals. Others are seeking clues in the blood. Researchers at Washington University in St. Louis recently reported that a protein linked⁵ to Alzheimer’s disease can estimate within a few years when some people develop noticeable symptoms. Still, much more research is needed before these tests can predict who might come down with the disease—and precisely when they might start to experience memory loss.
一部分研究者尝试通过脑部影像、肠道活检，寻找能提前预警痴呆症的其他标志物；另一部分研究者则从血液中探寻线索。圣路易斯华盛顿大学的研究团队近期公布研究成果：一种与阿尔茨海默病相关的蛋白质，可在数年内预判部分人群出现明显病症的时间。但想要依靠这类检测手段预测患病概率以及记忆力衰退的确切发作时间，仍需开展大量后续研究。
In the meantime, experts are working to link other physical or social signs that may appear years before a faltering memory. None of these definitively indicate that dementia is on the way. (Thyroid, vitamin-deficiency, and other treatable health issues could be behind some of the changes.) But, especially when they occur in combination, these factors could offer important clues that should trigger further evaluations by physicians, perhaps even leading to earlier diagnoses.
与此同时，专家们也在梳理那些早在记忆力衰退数年前就可能出现的身体与生活异常信号。当然，这些迹象并不能百分百判定患者即将患上痴呆症（部分异常也可能由甲状腺疾病、维生素缺乏等可治愈的病症引发）。但一旦多种症状同时出现，就会成为重要的警示线索，提醒医生为患者做进一步检查，甚至有望实现疾病的早期确诊。
