In recent years, some research has suggested that a high-fat diet may be bad for the brain, at least in lab animals. Can exercise protect against such damage? That question may have particular relevance now, with the butter-and cream-laden holidays fast approaching. And it has prompted several new and important studies.
近年来，一些研究表明高脂饮食可能对大脑有害，至少动物实验的情况如此。那么，运动能否帮助我们抵抗这种损害呢?随着节日到来，一大波充斥着黄油和奶酪的食品正在袭来，这个问题有了特殊的重要性，由此也带来了一些新的重要实验。
The most captivating of these, presented last month at the annual meeting of the Society for Neuroscience in New Orleans, began with scientists at the University of Minnesota teaching a group of rats to scamper from one chamber to another when they heard a musical tone, an accepted measure of the animals' ability to learn and remember.
上个月，在新奥尔良神经科学学会(Society for Neuroscience in New Orleans)年会上，明尼苏达州大学(University of Minnesota)的科学家们提交了一个最为吸引人的发现：他们令一组大鼠听到音乐后从一个小室疾走到另一个小室，这是一个被普遍认可的测量动物学习和记忆能力的实验。
For the next four months, half of the rats ate normal chow. The others happily consumed a much greasier diet, consisting of at least 40 percent fat. Total calories were the same in both diets.
接下来四个月，一半的老鼠正常饮食，另一半则愉快地享用更为油腻的饮食，其中包含至少40%的脂肪。两种饮食的总卡路里量是一样的。
After four months, the animals repeated the memory test. Those on a normal diet performed about the same as they had before; their cognitive ability was the same. The high-fat eaters, though, did much worse.
四个月后，动物们再次接受记忆测试。正常饮食的大鼠表现与之前一样;认知能力也一样。而高脂饮食组的表现就差得多了。
Then, half of the animals in each group were given access to running wheels. Their diets didn't change. So, some of the rats on the high-fat diet were now exercising. Some were not. Ditto for the animals eating the normal diet.
接下来，两组各有一半大鼠被提供了滚轮装置。它们的饮食没有变化。这样，高脂饮食组的一半大鼠开始运动，另一半则没有运动。正常饮食组的大鼠也是同样的情况。
For the next seven weeks, the memory test was repeated weekly in all of the groups. During that time, the performance of the rats eating a high-fat diet continued to decline so long as they didn't exercise.
接下来的七周中，所有组别每周进行一次记忆测试。在这一阶段中，高脂饮食组的大鼠如果没有运动，表现继续下降。
But those animals that were running, even if they were eating lots of fat, showed notable improvements in their ability to think and remember.
但是，那些在滚轮上跑步的大鼠虽然也摄入了大量脂肪，但思考和记忆能力有了明显的提升。
After seven weeks, the animals on the high-fat diet that exercised were scoring as well on the memory test as they had at the start of the experiment.
七周后，高脂饮食的运动大鼠在记忆测试方面的评分已经恢复到了试验开始时的水平。
Exercise, in other words, had "reversed the high-fat diet-induced cognitive decline," the study's authors concluded.
研究作者得出了结论：运动“逆转高脂饮食带来的认知下降”。
That finding echoes those of another study presented last month at the Society for Neuroscience meeting. In it, researchers at Kyoto University in Japan gathered a group of mice bred to have a predisposition to developing a rodent version of Alzheimer's disease and its profound memory loss.
这一发现与另一项神经科学学会会议发表的研究互相呼应。在那项研究中，日本京都大学(Kyoto University)的研究人员喂食一组小鼠，使之易于患上啮齿动物的阿尔茨海默症和严重的记忆丧失。
Earlier studies by the same scientists had shown that a high-fat diet exacerbated the animals' progression to full-blown dementia, and that both a low-fat diet and exercise slowed the animals' mental decline.
同一批科学家早先的研究已经表明，高脂饮食会加剧动物病情进展为完全性痴呆，而低脂饮食和运动都能减缓动物的智力下降。
But it hadn't been clear in these earlier experiments which was more effective at halting the loss of memory, a leaner diet or regular rodent workouts.
但是，这些早期试验并未明确，清淡的饮食或有规律的运动，哪个对阻止记忆丧失更有效。
So the scientists set out now to tease out the effects of each intervention by first feeding all of their mice a high-fat diet for 10 weeks, then switching some of them to low-fat kibble, while moving others to cages equipped with running wheels.
所以，科学家开始梳理出不同干预措施的效果，他们首先给所有小鼠喂食高脂饮食10周，然后让其中一部分改吃低脂粗粮，另一些转移到装有滚轮的笼子里。
A third group began both a low-fat diet and an exercise routine, while the remainder of the mice continued to eat the high-fat diet and didn't exercise.
第三组则予以低脂饮食和规律锻炼，而其余小鼠喂养高脂饮食且不运动。
After an additional 10 weeks, this last group, the animals that ate lots of fat and lounged around their cages, had developed far more deposits of the particular brain plaques associated with Alzheimer's disease than the other mice. They also performed much more poorly on memory tests.
又过了10周后，最后一组进食大量脂肪而宅在笼子里不运动的小鼠，生成了与阿尔茨海默症有关的特殊大脑斑块，斑块的量远甚于其他小鼠。它们在记忆测试中也表现得远远逊色。
The mice that had been switched to a low-fat diet had fewer plaques and better memories than the control group.
相比对照组，低脂饮食组的小鼠斑块较少，记忆力也更好。
But the mice that were exercising had even healthier brains and better memory scores than the low-fat group -- even if they had remained on a high-fat diet. In other words, exercise was "more effective than diet control in preventing high-fat diet-induced Alzheimer's disease development," the authors write.
但是，相比低脂组，运动的小鼠大脑更为健康，记忆评分也更高——尽管它们是高脂饮食的。作者在论文中写到，换言之，运动“在预防高脂饮食带来的阿尔茨海默症进展中比饮食节制更有效”。
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