白天常常犯困可能是阿爾茲海默症的跡象

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.

研究人員知道像阿爾茲海默症這樣複雜的病情並不是由一個簡單的原因導致的。遺傳因素會導致退行性腦障礙、剝奪人們的記憶，而與年老相關的生物過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.

但近年來，科學家發現了可能影響患阿爾茲海默症風險的一些行爲。在JAMA Neurology期刊最新發表的一篇研究中，一組科學家稱睡眠--尤其是白天犯困--可能是阿爾茲海默症的跡象。

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.

梅奧診所的放射學副教授Prashanthi Vemuri和她的同事試圖解決這一領域中令人費解的問題。研究表明阿爾茲海默症患者往往睡眠紊亂，這也是說得通的：生物研究最近揭示，當大腦處於休眠狀態時，會清除澱粉體的沉積、清除積聚的蛋白質，最終扼制阿爾茲海默症的神經細胞。但關於澱粉體斑塊沉積是否導致睡眠紊亂，或者睡眠習慣的改變是否導致蛋白質的積聚這一點，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.

爲了弄清楚，Vemuri和她的團隊利用了一項長期研究，研究對象是梅奧診所衰老研究的近3000位老年人，他們都來自明尼蘇達州奧姆斯特德縣。爲開展研究，Vemuri挑選了283位非老年癡呆症患者，他們都已年過70，並回答了有關睡眠習慣的問題、同意在7年的研究時間段內做幾次大腦掃描，查看腦內的澱粉體。

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.

在所有的研究受試者中，22%的人稱他們有白天嗜睡的問題，這是睡眠紊亂的表現。當Vemuri將所有志願者最初的大腦掃描結果與最終的結果對比時，她發現：隨着研究的展開，那些稱自己白天總是犯困的志願者更有可能出現大腦中的澱粉體增多。

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.

與那些白天不嗜睡的志願者相比，這些人的蛋白質也往往沉積更快。此外，大腦中的兩個區域含有最多的澱粉體：扣帶回前部和扣帶楔前葉。