随着年龄的增大，我们大脑不断缩小是不可避免的事情，神经细胞逐渐失去连接并死去，使思维功能因神经网络变薄而受到影响。但是最新的针对老年人的研究发现，大脑的萎缩并不是完全不可逆转的，近年来，越来越多的研究发现进入流金岁月之后，保持生理和精神上的活跃将大有裨益，保健专家们则鼓励众多老年人通过保持丰富的人际关系网和维系家庭关系来活跃大脑，通过学习新的技能来保持思维敏捷。填字游戏、学习新的语言以及玩棋类游戏等——每样都需要调动思维运转。

　　但是研究者想知道到底是锻炼身体还是脑力活动更有助于保持认知能力的完整性，或者是两者组合更有作用。所以在新的研究中，研究人员对638名于1936年出生在苏格兰的老年人的病历做了调查，在他们70岁的时候，填写一张关于详细的健身习惯的调查问卷，以及使用大脑思考和参加社交活动的频率。当他们73岁时，科学家再对他们的大脑进行核磁共振扫描，将大脑中脑白质体积的改变（脑皮质主要是由连接脑各个脑部区域的神经网组成）与之前问卷调查结果进行对比研究。

　　这些老年人的健身锻炼包括了从家务琐事到过度运动，或者一周参与多次竞技性体育项目。这三年来，那些健身活动频繁的老年人具有最大的脑体积，相比而言那些不怎么运动的老年人来说，他们的脑白质几乎没有出现萎缩。这揭示了老年人进行有规律的运动可以防止产生年龄引起的大脑衰退。而研究发现那些从事脑力劳动的老年人却在这方面并没有什么改观。

　　“70多岁的人继续参加锻炼的话，例如每周经常散步，相比不怎么运动的同龄人来说，脑萎缩和其它大脑衰老迹象出现的机率会大大降低”，苏格兰爱丁堡大学研究者阿兰。 J. 高在报告中提到，“相反，我们的研究结果显示，从三年之后的核磁共振扫描结果中看来，经常参与脑力运动和社交活动的老年人在脑体积上并没体现出优势。”

　　先前，发表在温哥华“老年痴呆症协会国际会议”上的四个研究发现，那些经常散步，轻体力劳动和参加有氧锻炼的老年人，记忆力明显优于那些长期久坐不动的老年人，并且几乎不会出现老年痴呆的情况。

　　综上所述，研究结果与传统认识恰好相反。老年人脑部的不可逆萎缩应归咎于愈发虚弱的体质和迟钝的思维。最新的研究同样认为衰老的过程，包括认知功能的退化，并不是一成不变的，我们可以通过相对温和的干预，比如散步，来延缓它的发生。

　　锻炼是如何保持老年人大脑活力的目前还不清楚，但是研究者推测，持续的锻炼，特别是有氧运动，能够促进心脏机能，从而使富含营养的血液充分流向大脑，滋养神经元细胞。经常参加体育锻炼的人在身体和精神上都将变得更加健康。作者写道，“我们不能忽视锻炼为身体带来健康的可能性”。不管怎样，前后研究结果都一致认为锻炼将是一个对身体和大脑都有益的事情，即使你是老年人也同样如此。

　　译文：

　　It’s inevitable that as we age, our brains get smaller. Nerves die off, losing their connections, and that leads to a thinned out network feeding our thinking functions. But brain shrinkage isn’t inevitable, according to the latest study of elderly adults.

　　In recent years, as more research reveals the benefits of staying both physically and mentally active into the golden years, health officials have been urging older people to exercise more and stay mentally engaged by maintaining a rich network of friends and family connections and by learning new skills to keep their brains sharp. Crossword puzzles, learning a new language, playing board games — anything that requires some thought can do the trick.

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　　But researchers wanted to know whether physical activity or mental activity was better at keeping cognitive functions intact, or whether there was something about the combination that helped elderly stay sharp. So in the new study, researchers examined the medical records of 638 people from Scotland born in 1936. At age 70, the participants filled out questionnaires detailing their exercise habits as well as how often they engaged in stimulating mental and social activities. When they turned 73, the scientists took MRIs of their brains and matched their size, as well as any changes in the volume of white matter, which makes up the web of nerves that connect various brain regions, to the volunteers’ questionnaire answers.

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　　The participants reported a range of physical activity, from household chores to heavy exercise or playing competitive sports several times a week. Over the three years, those who exercised the most had the largest brains, and showed the least shrinkage in white matter compared to those who were the least active, suggesting regular exercise in old age could protect the brain from age-related decline. Those who reported engaging in more intellectual pursuits didn’t show the same benefit.

　　“People in their seventies who participated in more physical exercise, including walking several times a week, had less brain shrinkage and other signs of aging in the brain than those who were less physically active,” said study author Alan J. Gow from the University of Edinburgh in Scotland in a statement. “On the other hand, our study showed no real benefit to participating in mentally and socially stimulating activities on brain size, as seen on MRI scans, over the three-year time frame.”

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　　Previously, four studies presented at the Alzheimer’s Association International Conference in Vancouver also found that elderly adults who exercised regularly, including taking walks, working with light weights and aerobic training, had fewer “senior moments” and improved memory than those who were more sedentary.

　　Taken together, the findings contradict the traditional belief that older people inevitably become more frail physically, and less sharp mentally. The most recent studies also suggest that aging processes, including the decline in cognitive functions, isn’t permanent, but can be slowed by relatively moderate interventions such as walking.

　　How physical activity protects the brain still isn’t clear, but the researchers speculate that consistent exercise, particularly aerobic activities, promotes heart health, which in turn keeps nutrient-rich blood flowing to the brain to nourish neurons. People who are more physically active may also be healthier to begin with, both physically and mentally. “The possibility that physical activity is a proxy for better general health should not be overlooked,” the authors write. Either way, the latest findings, coupled with previous results, suggest that physical activity can be good for both the body and the brain, even into old age.

　　The study was published in n Neurology, the medical journal of the American Academy of Neurology.