白天常常犯困可能是阿尔兹海默症的迹象

Researchers know that a condition as complicated as Alzheimer's can't be traced to a single or simple cause. Genetic factors contribute to the degenerative brain disorder that robs people of their memory, and biological process related to aging play a role as well.

研究人员知道像阿尔兹海默症这样复杂的病情并不是由一个简单的原因导致的。遗传因素会导致退行性脑障碍、剥夺人们的记忆，而与年老相关的生物过程也起到了一定作用。

But in recent years, scientists have uncovered some behaviors that may also influence Alzheimer's risk. In the latest study published in JAMA Neurology, a group of them report how sleep - daytime sleepiness, in particular - may be an indicator of Alzheimer's.

但近年来，科学家发现了可能影响患阿尔兹海默症风险的一些行为。在JAMA Neurology期刊最新发表的一篇研究中，一组科学家称睡眠--尤其是白天犯困--可能是阿尔兹海默症的迹象。

Prashanthi Vemuri, an associate professor of radiology at the Mayo Clinic, and her colleagues wanted to address a puzzling problem in the field. Studies showed that people with Alzheimer's disease tend to have disrupted sleep, which made sense: biological studies have recently revealed that while the brain sleeps, it clears away deposits of amyloid, the protein that builds up and eventually strangles nerve cells in Alzheimer's disease. But it wasn't clear whether the amyloid plaque deposits led to the disrupted sleep, or whether changes in sleep habits contributed to the buildup of the protein.

梅奥诊所的放射学副教授Prashanthi Vemuri和她的同事试图解决这一领域中令人费解的问题。研究表明阿尔兹海默症患者往往睡眠紊乱，这也是说得通的：生物研究最近揭示，当大脑处于休眠状态时，会清除淀粉体的沉积、清除积聚的蛋白质，最终扼制阿尔兹海默症的神经细胞。但关于淀粉体斑块沉积是否导致睡眠紊乱，或者睡眠习惯的改变是否导致蛋白质的积聚这一点，尚未可知。

To find out, Vemuri and her team took advantage of a long-running study of nearly 3,000 older people in the Mayo Clinic Study of Aging, all of whom were recruited from Olmsted County, Minn. For the study, Vemuri selected 283 people without dementia who were over 70, who answered questions about their sleep habits and agreed to have several brain scans for amyloid over the seven-year study period.

为了弄清楚，Vemuri和她的团队利用了一项长期研究，研究对象是梅奥诊所衰老研究的近3000位老年人，他们都来自明尼苏达州奥姆斯特德县。为开展研究，Vemuri挑选了283位非老年痴呆症患者，他们都已年过70，并回答了有关睡眠习惯的问题、同意在7年的研究时间段内做几次大脑扫描，查看脑内的淀粉体。

Among the people in the study, 22% reported problems with daytime sleepiness, a sign of disordered sleep. When Vemuri compared the brain scans of all of the volunteers from the start of the study to the end, she found that people who reported excessive daytime sleepiness at the start of the study were more likely to show increases in amyloid in their brains as the study progressed.

在所有的研究受试者中，22%的人称他们有白天嗜睡的问题，这是睡眠紊乱的表现。当Vemuri将所有志愿者最初的大脑扫描结果与最终的结果对比时，她发现：随着研究的展开，那些称自己白天总是犯困的志愿者更有可能出现大脑中的淀粉体增多。

These people also tended to show faster deposition of the protein than those who did not report daytime drowsiness. What's more, the amyloid was heaviest in two regions of the brain: the anterior cingulate and cingulate precuneus.

与那些白天不嗜睡的志愿者相比，这些人的蛋白质也往往沉积更快。此外，大脑中的两个区域含有最多的淀粉体：扣带回前部和扣带楔前叶。