微信加盟:想让孩子们富裕？请给他们减轻压力

想让孩子们富裕？请给他们减轻压力

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2009-04-09 11:20:55    作者： 刘丰祎（译）     来源： 新东方 How poverty passes from generation to generation is now becoming clearer. The answer lies in the effect of stress on two particular parts of the brain
贫穷在代间是如何传递的问题逐渐清晰。答案在于压力对大脑内两处特别部位的影响。

THAT the children of the poor underachieve in later life, and thus remain poor themselves, is one of the enduring problems of society. Sociologists have studied and described it. Socialists have tried to abolish it by dictatorship and central planning. Liberals have preferred democracy and opportunity. But nobody has truly understood what causes it. Until, perhaps, now.
The crucial breakthrough was made three years ago, when Martha Farah of the University of Pennsylvania showed that the working memories of children who have been raised in poverty have smaller capacities than those of middle-class children. Working memory is the ability to hold bits of information in the brain for current use—the digits of a phone number, for example. It is crucial for comprehending languages, for reading and for solving problems. Entry into the working memory is also a prerequisite for something to be learnt permanently as part of declarative memory—the stuff a person knows explicitly, like the dates of famous battles, rather than what he knows implicitly, like how to ride a bicycle.
Since Dr Farah’s discovery, Gary Evans and Michelle Schamberg of Cornell University have studied the phenomenon in more detail. As they report in this week’s Proceedings of the National Academy of Sciences, they have found that the reduced capacity of the memories of the poor is almost certainly the result of stress affecting the way that childish brains develop.
Dr Evans’s and Dr Schamberg’s volunteers were 195 participants in a long-term sociological and medical study that Dr Evans is carrying out in New York state. At the time, the participants were 17 years old. All are white, and the numbers of men and women are about equal.
To measure the amount of stress an individual had suffered over the course of his life, the two researchers used an index known as allostatic load. This is a combination of the values of six variables: diastolic and systolic blood pressure; the concentrations of three stress-related hormones; and the body-mass index, a measure of obesity. For all six, a higher value indicates a more stressful life; and for all six, the values were higher, on average, in poor children than in those who were middle class. Moreover, because Dr Evans’s wider study had followed the participants from birth, the two researchers were able to estimate what proportion of each child’s life had been spent in poverty. That more precise figure, too, was correlated with the allostatic load.
The capacity of a 17-year-old’s working memory was also correlated with allostatic load. Those who had spent their whole lives in poverty could hold an average of 8.5 items in their memory at any time. Those brought up in a middle-class family could manage 9.4, and those whose economic and social experiences had been mixed were in the middle.
These two correlations do not by themselves prove that chronic stress damages the memory, but Dr Evans and Dr Schamberg then applied a statistical technique called hierarchical regression to the results. They were able to use this to remove the effect of allostatic load on the relationship between poverty and memory discovered originally by Dr Farah. When they did so, that relationship disappeared. In other words, the diminution of memory in the poorer members of their study was entirely explained by stress, rather than by any more general aspect of poverty.
To confirm this result, the researchers also looked at characteristics such as each participant’s birthweight, his mother’s age when she gave birth, the mother’s level of education and her marital status, all of which differ, on average, between the poor and the middle classes. None of these characteristics had any effect. Nor did a mother’s own stress levels.
That stress, and stress alone, is responsible for damaging the working memories of poor children thus looks like a strong hypothesis. It is also backed up by work done on both people and laboratory animals, which shows that stress changes the activity of neurotransmitters, the chemicals that carry signals from one nerve cell to another in the brain. Stress also suppresses the generation of new nerve cells in the brain, and causes the “remodelling” of existing ones. Most significantly of all, it shrinks the volume of the prefrontal cortex and the hippocampus. These are the parts of the brain most closely associated with working memory.
Children with stressed lives, then, find it harder to learn. Put pejoratively, they are stupider. It is not surprising that they do less well at school, end up poor as adults and often visit the same circumstances on their own children.
Dr Evans’s and Dr Schamberg’s study does not examine the nature of the stress that the children of the poor are exposed to, but it is now well established that poor adults live stressful lives, and not just for the obvious reason that poverty brings uncertainty about the future. The main reason poor people are stressed is that they are at the bottom of the social heap as well as the financial one.
Sir Michael Marmot, of University College London, and his intellectual successors have shown repeatedly that people at the bottom of social hierarchies experience much more stress in their daily lives than those at the top—and suffer the consequences in their health. Even quite young children are socially sensitive beings and aware of such things.
So, it may not be necessary to look any further than their place in the pecking order to explain what Dr Evans and Dr Schamberg have discovered in their research into the children of the poor. The Bible says, “the poor you will always have with you.” Dr Evans and Dr Schamberg may have provided an important part of the explanation why.

贫困家庭的孩子在后来的学习中成就欠佳，而且他们成人后仍然贫穷，这是一个长期存在的社会问题之一。社会学家对此已经进行了研究和描述；社会主义者们曾试图通过专制和计划经济的方式废除这一现象；自由主义者们则倾向于用民主和机会的方法来废除贫穷。但是，可能直到现在，没有一个人正真理解是什么导致了贫穷。

关键性的突破在3年前取得，当时来自宾夕法利亚大学(University of Pennsylvania)的Martha Farah的研究表明，来自贫困家庭儿童的工作记忆力比那些来自中产家庭儿童们的工作记忆力要低。工作记忆力是在大脑中记住为当前所用信息的一种能力---比如记住电话号码的能力。这种能力对于理解语言、阅读以及解决问题都非常关键。工作记忆的获得也是对作为陈述性记忆一部分的永久性学习某些事物的一种前提条件。陈述性记忆是指一个人清新明白地知道的东西，比如著名战役的日期，而不是那些他非明显知道的东西，比如怎样骑自行车。

自从Farah博士的发现以来，来自康奈尔大学(Cornell University)的Gary Evans 以及Michelle Schamberg仔细研究了这种现象。他们发现那些贫困儿童记忆力的减少乎肯定是由于压力的结果，这些压力影响了小孩大脑的发展，他们的研究结果发表在本周的《美国科学院院报》（Proceedings of the National Academy of Sciences）杂志上。

Evans 和 Schamberg博士的195名志愿者们参与了Evans博士在纽约州进行的一项长期的社会和医学研究。在当时，这些参与者们的年龄为17岁。所有参与者都是白人，而且男性和女性的数目一样。

为了测量个体在生活中所受的压力，Evans 和 Schamberg博士使用“非稳态负载”作为指数。这个指数是把六项变量的值结合起来而得到，这个六项变量为：舒张压和收缩压；3种与压力相关的荷尔蒙浓度；体重指数（测量肥胖的指数）。对于所有的六种指数，数值越高表明生活压力越大；在贫困儿童中，所有的这六项指标的平均值都高于中产家庭儿童的相应平均值。而且，因为Evans博士的研究始于参与者刚出生之后，其研究范围更加广，这使得Evans 和 Schamberg博士能估测每个儿童在贫困中度过了多少时间。同时，这些更精确的数据也与“非稳态负载”形成相关。

17岁孩子的工作记忆力也与“非稳态负载”相关。那些整个生活都在贫困中度过的儿童在任何时候平均能记住8.5件物品。那些在中产家庭中长大的儿童能记住9.4件物品，而那些来自经济和社会经历不定的家庭的儿童们能记住的物品件数介于上述两个数值之间。
上述两种相关本身并不能证明长期压力损害了记忆，不过Evans 和Schamberg博士应用层次回归的统计技术得出了该结论。他们用该技术消除了“非稳态负载”效应对贫穷和记忆之间关系的影响，这个关系首先由Farah 博士发现。当Evans 和Schamberg博士采用层次回归统计技术进行分析的时候，贫穷和记忆之间的关系就消失了。换句话说，他们研究中的那些贫穷儿童们的记忆力减少完全可以用压力来解释，而不是贫穷的一些普遍因素。

为了确认这个结果，研究者们也研究了每个参与者的其它特征，比如，他们出生时的体重、他们的母亲生他们时候的年龄、他们母亲的受教育水平以及婚姻状况，在贫穷家庭与中产家庭之间，平均来看所有这些特征都有差异。但是没有上述任何一项特征对记忆力有影响，母亲自身的压力水平也不产生影响。

压力，而且仅仅只是压力导致了贫穷儿童们的工作记忆受损的这个假设似乎是强有力的。这个假设也得到了在人和实验室动物身上所做工作的支持，这些工作表明压力改变神经传质的活动。神经传质这种化学物质把信号在大脑内从一个神经细胞传递到另外一个细胞。压力也能抑制大脑内新神经细胞的生成，从而导致已有神经细胞的“重建”。最重要的是，压力致使前额皮层质和海马区体积缩小。而前额皮层质和海马区与工作记忆联系最紧密。

生活在压力下的儿童们更难去学习。说得不好听一点儿，这些儿童们更笨。他们在学校里学习不好、成年后也受穷、在他们的孩子身上也同样发现这样的情景也就不足为奇了。

Evans和 Schamberg博士的研究没有考察这些贫穷儿童们遭受的压力的本质，但是，贫穷成年人在压力重重下生活已经得到公认，而且他们的压力不仅仅是因为贫穷引起对未来的担忧这一明显的原因。贫困者们感到压力的主要原因在于他们不仅在经济上处于社会的底层，而且他们的社会地位也同样处于底层。

来自伦敦大学学院（University College London）的Michael Marmot爵士以及他的才华卓著的继任者们反复表明，与处于社会上层的人士相比，那些处于社会底层的人们在他们的日常生活中经历了多得多的压力---因此他们的健康受到损害。即使年纪很小的儿童对社会也很敏感，他们也知道压力这类事情。

所以，为了解释Evans和Schamberg博士在他们研究贫穷儿童中的发现，我们可能只需要看看这些儿童们在社会上所处的地位就够了。圣经中说到：“因为常有穷人和你们同在。” Evans 和Dr Schamberg博士可能为这种情况提供了一部分很重要的解释。

Vocabulary:

Poverty：贫穷
Underachieve: （尤指学习上）未发挥水平，未展现实力
Enduring: 长期的
Sociologist: 社会学家
Socialist: 社会主义者
Abolish: 废除
Dictatorship: 专制；独裁
Liberal: 自由主义者
Crucial: 关键的
Breakthrough: 突破
Digit: 数字
Comprehend: 理解
Prerequisite: 前提
Permanent: 永久性的
Declarative: 陈述性的
Explicitly: 明显地
Implicitly: 暗示地
Participant: 参与者
Allostatic load:（心理学术语）非稳态负荷
Variable: 变量
Diastolic: 舒张的
Systolic: 收缩的
Concentration: 浓度
Hormone: 荷尔蒙
Obesity: 肥胖；肥胖症
Precise: 精确的
Chronic: 慢性的
Hierarchical regression: 层次回归
Diminution: 减少；降低
Characteristics: 特点；特质
Marital: 婚姻的
Hypothesis: 假设
Neurotransmitter: 神经递质
Suppress: 压制
Shrink: 缩小
Prefrontal cortex: 前额皮质
Hippocampus: 海马组织
Pejoratively: 蔑视地
Intellectual: 智力的； 有才智的
Successor: 继任者
Pecking order: 社会地位高低顺序 （编辑：赵露）

注：英文原文来自The Economist 《经济学人》http://www.economist.com