Your scale arm has crashed to the floor. 你天平的一端已坠地。

　　You've tripped the cascade, setting fire to the forest, causing inflammation, tangles, and cell death. 你触发了连锁反应，引发了森林火灾，导致了炎症、神经纤维缠结以及细胞凋亡。

　　You should be symptomatic for Alzheimer's. 你表现出老年痴呆的症状。

　　You should be having trouble finding words and keys and remembering what I said at the beginning of this talk. But you might not be. 你在措辞和找钥匙时会碰到麻烦，并且回想不起我一开始讲的内容。也许你不会这样。

　　There's one more thing you can do to protect yourself from experiencing the symptoms of Alzheimer's, 另外还有一件事可以帮助你免于老年痴呆的症状，

　　even if you have the full-blown disease pathology ablaze in your brain. 哪怕你的大脑已病入膏肓。

　　It has to do with neural plasticity and cognitive reserve. 它需解决神经可塑性和认知储备问题。

　　Remember, the experience of having Alzheimer's is ultimately a result of losing synapses. 记住，老年痴呆症的发作是突触损失的最终后果。

　　The average brain has over a hundred trillion synapses, which is fantastic; we've got a lot to work with. 一般大脑有超过万亿的突触，这很不可思议，我们有这么庞大的数量。

　　And this isn't a static number. We gain and lose synapses all the time, through a process called neural plasticity. 而这一数字不是一成不变。我们在一个叫做神经可塑性的过程之中，不断生成和消耗着突触。

　　Every time we learn something new, we are creating and strengthening new neural connections, new synapses. 每当我们习得新东西，我们建立并强化新的神经连接，新的突触产生了。

　　In the Nun Study, 678 nuns, all over the age of 75 when the study began, were followed for more than two decades. 在Nun研究中，研究开始时，678位修女全都年过七十五岁，进行了二十多年的研究。

　　They were regularly given physical checkups and cognitive tests, and when they died, their brains were all donated for autopsy. 她们会定期接受身体检查和认知测试，如果不幸去世，她们的大脑都捐献出去用于验尸。

　　In some of these brains, scientists discovered something surprising. 科学家们在一些大脑中发现了一些神奇的东西。

　　Despite the presence of plaques and tangles and brain shrinkage -- what appeared to be unquestionable Alzheimer's 尽管样斑块、神经纤维缠结和大脑的萎缩，这些现象似乎是老年痴呆症无疑，

　　the nuns who had belonged to these brains showed no signs of having the disease while they were alive. 然而这些大脑的主人，那些修女却没有在生前表现出患有老年痴呆的症状。