美国科学家称老年人正在变得更加健康、快乐，也更加独立。本月随后即将发表的一项14年的研究结果揭示，受各种老龄疾病所袭扰的人群数量正在不断减少。并且疾病发作的时间也大大地推后了。

Elderly people are growing healthier, happier and more independent, say American scientists. The results of a 14-year study to be announced later this month reveal that the diseases associated with old age are afflicting fewer and fewer people and when they do strike, it is much later in life.

在过去的14年中，国家卫生保健长期调查对超过2万名65岁以上的男性和女性的健康状况和生活方式进行了数据统计。研究者目前正在分析1994年所收集的数据结果。他们谈到在这个年龄群体中的主要疾病，即关节炎、高血压和循环系统的问题的发病率正在一年年地减少。数据也证实这些疾病的发病率的下降也呈现出加速的趋势。罹患其他老龄疾病，如老年痴呆症、中风、动脉硬化和肺气肿的人数也正在变得越来越少。

北卡罗来纳杜克大学的人口统计学家肯尼恩·曼顿(Kenneth Manton)说：“这确实引发了一个问题，即多大年纪认为是正常的老年。”他谈到，在1982年，对于65岁的人医生视为正常的问题而现在直到70岁或75岁才会出现。

In the last 14 years, the National Long-term Health Care Survey has gathered data on the health and lifestyles of more than 20,000 men and women over 65. Researchers, now analysing the results of data gathered in 1994, say arthritis, high blood pressure and circulation problems - the major medical complaints in this age group - are troubling a smaller proportion every year. And the data confirms that the rate at which these diseases are declining continues to accelerate. Other diseases of old age - dementia, stroke, arteriosclerosis and emphysema - are also troubling fewer and fewer people.

很明显，某些疾病面对医学的飞速发展正在不断地溃退。但是也许还有其他的作用因素，例如在20世纪前25年当中儿童时期营养状况的改善给予了今天的老年人一个比他们前人更好的生命开端。

从负面来看，数据也揭示了在公共卫生领域的失败。这些失败引起了一些疾病的发病率的猛增。研究者说，一些癌症以及支气管病发病率的增加也许反映了如吸烟等个人习惯的改变和更差的空气质量。曼顿说：“这些也许是细微的影响，但是我们的受调查者暴露在越来越差的污染中已经超过60年了。我们看到一些影响不足为怪。”

'It really raises the question of what should be considered normal ageing,' says Kenneth Manton, a demographer from Duke University in North Carolina. He says the problems doctors accepted as normal in a 65-year-old in 1982 are often not appearing until people are 70 or 75.

曼顿揭示的—个有趣的关联是受过更好教育的人更有可能活得长久。例如：受过的学校教育少于8年的65岁的老妪平均可以期望活到82岁；而受教育时间更长的人，则可以多活7年。尽管这可以部分地归因于更高的收入，但是曼顿认为这主要是因为受教育者寻求更多的医疗照顾。

这次调查对于65岁以上的老年人的独立性也进行了评估，并又发现了一个引人注目的趋势。在1994年的受调查者中有几乎80％的人能够独立完成每天从吃饭到穿衣的括动，以及做饭和料理个人财务等复杂的生活事项。这个评估结果表明在人口中无自理能力的老人数量的大幅减少。如果14年前在美国的那些显而易见的趋势继续延续，那么研究者的计算就将是在今天的人口中有额外100万的失去自理能力的老人。曼顿认为，减缓这个趋势使美国政府在医疗保险体系中节省了2 000亿美元，这表明，美国人口的老龄化也许证明经济负担没有预期的沉重。

Clearly, certain diseases are beating a retreat in the face of medical advances. But there may be other contributing factors. Improvements in childhood nutrition in the first quarter of the twentieth century, for example, gave today's elderly people a better start in life than their predecessors.

很多老年人越来越强的独立能力也许与简单的家庭医疗船助设备的使用的大量增加有关。例如：对于加高的马桶坐椅的使用从这项研究开始以来已经增加了一倍多。淋浴椅的使用也增加了50％还多。根据麦克阿瑟基金会成功老龄化研究组的报告，这些发展也带来了一些健康方面的益处。这个研究组发现那些得以保留独立感的老人更有可能在老年阶段保持身体健康。

加利福尼亚大学欧文分校的神经科学家卡尔·科特曼说，每天保持一定水平的身体锻炼有益于心智机能。他发现在踏车上锻炼的老鼠可以提高它的穿经大脑的脑源性神经营养因子的水平。科特曼认为使得神经细胞保持功能的这种荷尔蒙可以防止人类大脑衰老。

On the downside, the data also reveals failures in public health that have caused surges in some illnesses. An increase in some cancers and bronchitis may reflect changing smoking habits and poorer air quality, say the researchers. 'These may be subtle influences,' says Manton, 'but our subjects have been exposed to worse and worse pollution for over 60 years. It's not surprising we see some effect.'

作为同一研究的一部分，来自洛杉矶南加利福尼亚大学的社会流行病学家特里萨·西曼发现，在70岁以上的老年人中，自尊与压力存在着联系。在诸如驾驶等挑战性的实验模拟活动中，那些觉得可以控制他们生命的老人分泌出较低水平的压力荷尔蒙——氢化可的橙。这些荷尔蒙的较长时间升高会引发心脏病。

但是独立性也有缺点。西曼发现，感觉疏离社会的老年人甚至在睡眠中也保持了较高水平的压力荷尔蒙。研究表明，独立性强的老年人如果知道他们在需要的时候可以得到帮助，那么他们的生活景况会是一种最佳的状态。

One interesting correlation Manton uncovered is that better-educated people are likely to live longer. For example, 65-year-old women with fewer than eight years of schooling are expected, on average, to live to 82. Those who continued their education live an extra seven years. Although some of this can be attributed to a higher income, Manton believes it is mainly because educated people seek more medical attention.

西曼说：“像有关老龄的许多研究一样。这些结果支持常识。它们也说明我们也许正在低估这些简单因素的影响。就像是你的祖母总是向你念叨的而最终证明是完全正确的事情一样。”

The survey also assessed how independent people over 65 were, and again found a striking trend. Almost 80% of those in the 1994 survey could complete everyday activities ranging from eating and dressing unaided to complex tasks such as cooking and managing their finances. That represents a significant drop in the number of disabled old people in the population. If the trends apparent in the United States 14 years ago had continued, researchers calculate there would be an additional one million disabled elderly people in today's population. According to Manton, slowing the trend has saved the United States government's Medicare system more than $200 billion, suggesting that the greying of America's population may prove less of a financial burden than expected.

The increasing self-reliance of many elderly people is probably linked to a massive increase in the use of simple home medical aids. For instance, the use of raised toilet seats has more than doubled since the start of the study, and the use of bath seats has grown by more than 50%. These developments also bring some health benefits, according to a report from the MacArthur Foundation's research group on successful ageing. The group found that those elderly people who were able to retain a sense of independence were more likely to stay healthy in old age.

Maintaining a level of daily physical activity may help mental functioning, says Carl Cotman, a neuroscientist at the University of California at Irvine. He found that rats that exercise on a treadmill have raised levels of brain-derived neurotrophic factor coursing through their brains. Cotman believes this hormone, which keeps neurons functioning, may prevent the brains of active humans from deteriorating.

As part of the same study, Teresa Seeman, a social epidemiologist at the University of Southern California in Los Angeles, found a connection between self-esteem and stress in people over 70. In laboratory simulations of challenging activities such as driving, those who felt in control of their lives pumped out lower levels of stress hormones such as cortisol. Chronically high levels of these hormones have been linked to heart disease.

But independence can have drawbacks. Seeman found that elderly people who felt emotionally isolated maintained higher levels of stress hormones even when asleep. The research suggests that older people fare best when they feel independent but know they can get help when they need it.

'Like much research into ageing, these results support common sense,' says Seeman. They also show that we may be underestimating the impact of these simple factors. 'The sort of thing that your grandmother always told you turns out to be right on target,' she says.