There are many known risk factors associated with suicide: those who take their own lives are statistically more likely to be white, male, and/or low-income. Surveys show that they are also more likely to have histories of depression, own fire arms and feel isolated. Many are divorced or have substance abuse problems. But a team of researchers found another risk factor that is less intuitive, even though it may be just as valid: living at a high altitude.

外國研究者通過大量事實發(fā)現(xiàn)：致人萌發(fā)“尋短見”念頭的因素眾多，輕生者中又以低收入的白人男性為主，調(diào)查發(fā)現(xiàn)，這類人通常有抑郁癥病史，有過犯罪經(jīng)歷和深感孤立無援。另外許多則是因為離婚和藥物濫用等問題，但最近，有一個研究組則發(fā)現(xiàn)了另一個不明顯而影響力有限的誘因——所處的海拔高度。

The team, lead by Dr. Barry Brenner from the University Hospitals Case Medical Center in Cleveland Ohio, analyzed 19 years worth of cause-of-death data from all 2,584 U.S. counties （between 1979 and 1998）。 In their study, published in High Altitude Medicine & Biology, they compared the 50 counties with the highest suicide rate to the 50 counties with the lowest, and found that county altitude was on average almost eight times higher in the areas with high suicide rates.

該小組研究了全美2584個縣在1979年到1998年間的十九年中導(dǎo)致自殺事件的所有數(shù)據(jù)，他們將發(fā)生率最高的50個縣與最低的50個縣驚醒對比，發(fā)現(xiàn)海拔相較于平均值高出八倍的地區(qū)的自殺率也會相應(yīng)的升高。

Even when the researchers controlled for five other suicide-related factors — two measures of income,race, age and population density of the county — the correlation was still strong. Wrote the scientists:

同時，這項調(diào)差還將另外五了因素列為了誘因，其中兩項與收入有關(guān)，此外，種族，年齡，以及密集程度，這些因素都具有強烈的相關(guān)性。科學(xué)家們說：

Prior reports of increased suicides in the U.S. Mountain Region （e.g., Colorado） have prompted speculation that the excess is owing to greater access to rearms, increased isolation, or reduced income. Even after controlling for these variables in our analysis, the positive correlation between altitude and suicide still exists, which suggests that the increased suicide rate in the regions with greatest altitude, such as the Mountain Region, may be owing to, at least in part, its altitude per se.

之前的報告中所稱的美國山地地區(qū)（例如科羅拉多州）的自殺率的上升與該地區(qū)槍支泛濫、隔離程度的提高以及收入的減少都可能存在著聯(lián)系。然而在這些數(shù)據(jù)進行歸納分析后，我們發(fā)現(xiàn)，所處的海拔高度與自殺事件之間也有關(guān)聯(lián)，這表明了在諸如山區(qū)這樣的高海拔地區(qū)的自殺率的上升的原因中，至少有一部本是因自身所處的環(huán)境（海拔）所致。

The authors note that there may be physiological reasons why high altitude may contribute to suicides; low barometric pressure in mountainous regions, for example, causes the body to become less efficient in transporting oxygen from the air, and these changes can affect brain functioning. In addition, they note, it's only suicides, and not other deaths that are positively associated with higher altitudes. While the results still need to be replicated, they at least suggest that achieving the “mountain high” may come at a dangerous price.

文章的作者還指出，有很多生理上的因素也說明了為何在高海拔地區(qū)會出現(xiàn)較高的“輕生”率，這些地區(qū)的大氣氣壓較低，由此導(dǎo)致了人體輸送氧氣的效率較低，這將影響到大腦功能。此外，除了自殺以外的其他死亡現(xiàn)象也和這一地理因素有關(guān)。盡管對于這項研究所提出的說法還有待檢驗，但它至少給我們提了個醒，人在“高處”不但不勝寒，或還不“安全”。