肥胖有损大脑,运动修复智力

But whether excessive fat cells alone were the underlying cause of the changes in the animals' brains was not clear. Other physiological factors "could have been contributing," said Alexis Stranahan, a professor at the Medical College of Georgia at Georgia Regents, who oversaw the study. So, to isolate the impact of the fat, the researchers simply removed most of it, surgically excising the large bands of fat that each mouse bore around its middle.
只是，人们一时还无法确定促使这些动物的大脑发生改变的根本原因是否仅限于脂肪细胞过剩。其他的生理因素“也可能发挥了一定作用，”该研究的负责人、乔治亚瑞金斯大学乔治亚医学院(Medical College of Georgia)的教授亚历克西斯·斯特拉纳汉(Alexis Stranahan)说。因此，为了将脂肪的影响单独分离出来，研究人员在每只小鼠的身体中段打了个孔，通过手术切除了大块大块的脂肪——可以说是它们体内的绝大部分脂肪。

After recovery, these slenderized mice showed almost no interleukin 1 in their bloodstreams and, Algernon-like, soon were acing cognitive tests that had stumped them before surgery.
等这些接受了抽脂瘦身的小鼠痊愈后，它们血液中的白细胞介素1全都几乎不见了，就像科幻小说里面的阿尔杰农（Algernon，是科幻小说《献给阿尔杰农的花》中一只接受脑部改造手术实验的仓鼠——译注）一样，它们不费吹灰之力就搞定了手术前一直把它们难倒的认知测试。

Conversely, when the scientists implanted the preserved fat pads into previously lean mice — and haven't we all had nightmares about something like that happening to us in our sleep? — the animals almost immediately grew dimmer, performing far worse than previously on cognitive tests, although nothing else in their lives had changed.
反之，当科学家们将之前保存下来的脂肪垫植入到以前纤瘦的小鼠体内（我们谁不曾做过这样的噩梦，梦见就在我们呼呼大睡时类似的厄运降临到我们自己身上？）时，它们几乎是立即就变得呆呆傻傻的，在认知测试中的表现也比过去糟糕许多，尽管它们生活中其他的各个方面都一如往常。

The results convincingly implicated fat cells as the primary cause of the mice's cognitive decline.
这些研究结果令人信服地证明了脂肪细胞即是造成小鼠认知能力下降的元凶。

But while provocative, the findings had little practical value for people, the scientists realized, since even the most extensive liposuction procedure in humans would remove far less fat than had been excised from the obese mice.
只是虽然这些发现弄得人心痒难耐，科学家们却认识到它对人类而言几乎没有什么实用价值，因为即便是人体所能承受的最广泛的吸脂手术，它所清除的脂肪量也要远远少于实验中从肥胖小鼠体内清除的脂肪量。

So the scientists turned, as a less-invasive alternative, to exercise. Gathering more of the obesity-prone mice, they allowed all of them to grow heavy, but then started half on a daily 45-minute program of treadmill running, with encouragement provided by small puffs of air if they began to flag. The other mice remained sedentary.
因此，科学家们将目光转向了无创性的替代方案：运动。他们收集了更多具有肥胖倾向的小鼠，并让它们都长到肥胖超重的程度。然后，他们将这些小鼠分作两半，让其中一半每天在小鼠跑步机上跑步45分钟，并在它们显出疲态时为它们吹送小小的“顺风”来鼓励它们。其余的小鼠则仍保持其久坐不动的生活方式。

After 12 weeks, the running mice still weighed about the same as the unexercised animals. But they had lost significant amounts of fat from around their middles, while adding lean muscle. More telling, they did much better on cognitive tests than the sedentary mice and, when the researchers examined tissue from their hippocampi, showed little evidence of inflammation and robust levels of the chemical marker of synaptic health. The results suggested that, as the scientists write in the study, "treadmill training normalized hippocampal function," even in animals born to be fat and that remained heavy.
12周后，每天跑步的小鼠体重依旧与从未运动的小鼠差不多。但他们身体中段的脂肪量已经显著减少，肌肉量却不断增加。更有说服力的是，它们在认知测试中的成绩远远优于久坐不动的小鼠。此外，在研究人员检查它们的海马组织时，也几乎没有看到任何可表明炎症存在的证据，反之，表征突触健康的化学标志物则十分充足。正如科学家们在研究论文中所写的，这些研究结果表明，“跑步机训练使海马的功能变得正常”，即使在那些天生容易发胖且仍然体重超重的动物中依然如此。

Of course, these studies were conducted in mice, not people, whose brains may respond very differently. But the possibility that humans, too, may respond in similar ways is tantalizing, Dr. Stranahan said, and the takeaway from her study worth repeating. "Get out and move," she said, even — and especially — if you carry extra weight. Talk with your doctor about a safe and tolerable exercise program, and then try to stick with that routine so that extra pounds won't weigh too heavily on your mind.
当然，这些研究都是在小鼠中进行的，人类的大脑很可能以迥异的方式来作应答。但我们也无法排除这一诱人的可能性：说不定人类大脑会与之类似呢？斯特拉纳汉博士指出，她这项研究的结论非常值得借鉴。“走出门去做运动吧，”她说，如果你腰上已经带了个“救生圈”就尤其需要赶快行动。跟你的医生谈谈，制定一个安全、可以承受的锻炼计划，然后尝试照着它坚持下去，让超重的体重不再那么让你伤脑筋。