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You know that feeling of walking into a room and, like, instantly forgetting why you're there?
你走进一个房间，立马忘记你为什么在那里，你知道这种感觉吧？
That's normal every now and again, but for people who go through chemotherapy, that kind of thing can happen all the time—and it's more than just forgetfulness, too.
偶尔出现这种情况很正常，但是对于接受化疗的人来说，总会发生这种事情，这还不仅仅是健忘的问题。
Undergoing chemo is also associated with trouble with working memory, the ability to learn new things, and motor functioning.
接受化疗还与工作记忆障碍、学习新事物的能力和运动功能有关。
As if going through cancer treatments wasn't hard enough by itself.
就好像接受癌症治疗本身还不够难受啊。
Many people call this experience "chemo brain", but scientists generally call it chemotherapy-induced cognitive impairment, or some variation on that.
许多人把这种经历称为“化疗脑”，但科学家们通常称之为化疗相关认知障碍（CICI），或其它一些叫法。
Researchers really started to acknowledge CICI back in the 1990s, but they still can't figure out exactly why it happens or how to treat it—even though it seems like it should be a simple "cause and effect"-type thing.
研究人员早在20世纪90年代就开始承认CICI的存在，但他们仍然无法确切地了解它发生的原因或如何治疗，即使它看起来应该是一个简单的“因果”类型的事情。
But just because something is hard to understand, doesn't mean it's impossible.
但某件事很难理解，并不意味着这是不可能做到的。
And by taking the problem one step at a time, they're making progress.
通过一步一步地解决这个问题，研究人员们正在取得进展。
Thankfully, CICI isn't anything lethal, but it does have an impact on everyday life—especially because the symptoms can last more than a decade after treatment.
谢天谢地，CICI并不是什么致命的疾病，但它确实会对日常生活产生影响，尤其是因为这些症状在治疗后可持续10多年。
Unfortunately, there are so many factors behind our current understanding of this condition that it can be hard to figure out what's causing it.
不幸的是，我们目前了解到有许多因素引发这种疾病，很难弄清楚病因是什么。
Some of these problems are research-related.
其中一些问题与研究本身有关。
For instance, most studies in this area are performed on breast cancer survivors, but the condition affects patients with all cancer types and we can't just assume that the results will transfer smoothly.
比如，这方面的大多数研究都是针对乳腺癌幸存者进行的，但是这种疾病会影响所有癌症类型的患者，我们不能假设结果能够顺利转换。
Since cancer involves mutating cells, it's as personal as someone's genetics.
因为癌症涉及细胞变异，所以它和某人的基因一样具有个性化的特点。
Also, researchers have inconsistent methods to study this phenomenon, which makes finding patterns difficult.
此外，研究人员也采用不同的方法来研究该现象，所以很难找到发病模式。
For example, a handful of studies might all use fMRIs to visualize brain activity and blood flow during a test.
例如，一些研究可能都使用功能磁共振成像技术，来查看测试期间的大脑活动和血流。
But one study might involve tests of working memory, while another tests verbal memory.
但一项研究可能涉及工作记忆测试，而另一项研究则涉及语言记忆测试
Or one might follow up with patients a week after chemo while another waits ten years.
或者是一项研究在化疗后一周随访病人，而另一项研究则等待十年再做随访。
Point is, there's a lot of variation.
关键是，变异太大。
And even once you get past the research problems—as much as you can do that—CICI still doesn't seem to have a clear explanation.
即使你尽可能多地克服研究本身产生问题，似乎仍然无法找到对CICI的明确解释。
That's partly because chemotherapy itself isn't just one or two drugs—it's not like you only have a couple of variables to look at.
部分原因是化疗本身用的不只是一两种药物，不是只查看几个变量就行了。
Since cancer is so personal, prescriptions can vary a lot, too.
由于癌症具有个性化的特点，处方也会有很大的区别。
Also—and this is a big one—researchers aren't even sure the cognitive impairments are entirely due to chemotherapy.
此外，还有个大问题，研究人员甚至无法确定认知障碍是否完全由化疗所引起。
A lengthy 2013 review noticed structural differences in the brains of people with cancer and those without, even before the cancer patients underwent chemo.
2013年，在一份冗长的综述研究中，研究人员注意到癌症患者和未患癌症的人大脑结构存在差异，甚至在癌症患者接受化疗之前，这些差异就存在了。
For example, cancer patients tended to have widespread decreases in the volume of certain brain tissues, which suggested that other factors played a role in their cognitive symptoms.
例如，癌症患者的某些脑组织体积普遍减少，这表明其他因素在他们的认知症状中发挥着作用。
So maybe something like stress was involved.
所以，可能是因为压力等原因所致。
Regardless, between the different types of cancer, methodologies, and treatments, it's really hard to find a general explanation for CICI.
不管怎么样，在不同类型的癌症、方法和治疗之间，很难给CICI找到一种普遍适用的解释。
So scientists have had to figure out a more complex way to approach this problem.
所以，科学家们不得不想出一种更复杂的方法来解决这个问题。
Instead of just looking at one cause or solution, they've had to tackle this like this do with a lot of other brain-related questions: one piece at a time.
他们不是只看一个原因或解决方案，而是在处理时要考虑许多其他与大脑相关的问题：一次一个。
And that's allowed them to make some progress.
这种做法他们取得了一些进展。
For the most part, research into CICI has focused on chemotherapy drugs, because even though there might be other mechanisms, this one is relatively easy to study.
在大多数情况下，对CICI的研究都集中在化疗药物上，因为即使存在其他机制，这种机制也相对容易研究。
After all, it's a lot easier to measure the amounts and types of medication someone got than to measure how stressed out they feel.
毕竟，测量一个人使用药物的数量和类型要比测查他们感到的压力容易得多。
One popular hypothesis is that the cognitive impairment is due to oxidative stress: a process caused by some chemo drugs that creates byproducts called free radicals.
一种广为流行的假设是，认知障碍源于氧化应激。氧化应激是由某些化疗药物引起的一种过程，它会产生称做自由基的副产物。
When it comes to cancer, these radicals are actually important, because they can keep cancer cells from spreading, so we might not want to get rid of them entirely.
说到癌症，这些自由基实际上很重要，因为它们可以阻止癌细胞扩散，所以我们可能不想完全把它们清除。
The problem is, they can also kick off a chain of events that leads to dangerous proteins entering the brain and killing neurons.
问题是，它们也能引发一连串事件，导致危险的蛋白质进入大脑并杀死神经元。
So researchers have been looking for a way to fight this—a way to keep the helpful effects of free radicals without allowing them to cause brain damage.
因此，研究人员一直在寻找一种解决该问题的方法，即保留自由基的有益作用，而又不让它们造成大脑损伤。
Basically, they've been trying to find a drug to protect people from their drugs.
基本上，他们一直试图找到一种药物来保护人们远离他们正在使用的药物。
And while it might sound a little silly, this research does seem to be going well.
虽然这听起来有点傻，但这项研究似乎进展得很顺利。
Take a 2018 study published in PLOS One.
以2018年发表在《公共科学图书馆期刊》上的一个研究为例。
In it, researchers wanted to see whether a compound called PAN-811 might protect against free radicals.
在这篇文章中，研究人员想知道一种叫做PAN-811的化合物是否可以保护人体免受自由基的侵害。
The compound is called a ribonucleotide reductase inhibitor, or RNRI, and in things like Petri dishes, it has previously been shown to help protect against free radicals.
这种化合物叫做核糖核苷酸还原酶抑制剂（RNRI），生长在培养皿中，以前的研究证明它有助于抵抗自由基。
In the 2018 experiment, researchers injected one group of rats with chemotherapy drugs and the other with harmless saline.
在2018年的实验中，研究人员给一组大鼠注射了化疗药物，另一组注射了无害的生理盐水。
Then, they injected some of the rats with PAN-811 and left the others untreated.
然后，他们给一些大鼠注射了PAN-811，其余大鼠未做处理。
A month later, they gave the rats memory and learning tests to gauge their cognitive abilities.
一个月后，他们给老鼠进行记忆和学习测试，衡量它们的认知能力。
And they found that PAN-811 seemed to reduce the cognitive impairment caused by the chemo drugs.
他们发现PAN-811似乎可以减少化疗药物引起的认知障碍。
The team suggested that this might have happened because PAN-811 interrupts the pathway that allows the free radicals to kill neurons.
研究小组认为，这可能是因为PAN-811阻断了自由基杀死神经元的路径。
And although that has potential to be awesome news, we will need to keep studying it to be sure it is effective and safe.
虽然这有可能成为超棒的好消息，但我们需要继续对其进行研究，确保它的有效性和安全性。
But someday, it could be a way to prevent or reduce CICI.
但总有一天，会有一种预防或减缓CICI的方法。
At the end of the day, CICI is a simple sounding problem with a really complicated answer that we're still unraveling.
归根结底，CICI是一个听起来很简单的问题，但其答案非常复杂，我们还在研究之中。
But as it becomes an issue for more and more people, it's something researchers will need to keep focusing on.
不过，随着它成为越来越多人关注的问题，研究人员需要继续关注它。
We will keep breaking it down into smaller and smaller pieces, and we will keep getting our answers.
我们将不断地把它分解成更小的问题，继续寻找答案。
If you're a fan of SciShow and you love learning weird things about the world, we have got a new treat for you directly from our studio!
如果你是科学秀的粉丝，你又喜欢学习稀奇古怪的东西，我们就直接从工作室为你送出一份新奖励！
A new patron reward: a podcast called SciShow After Hours, which is available only to our patrons on Patreon.
一个新的赞助奖励：是一个叫Scishow After Hours的播客，它只提供给我们Patreon上的赞助人。
While we make episodes of SciShow, we come across facts that are so weird and ridiculous that we have to share them.
我们制作科学秀时，遇到了一些光怪陆离的事，必须得分享一下。
Except, sometimes those facts aren't exactly PG.
但是，有时这些事并不太好讲。
So until now, we have just been keeping those things to ourselves, but we're finally going to start sharing them.
所以到目前为止，我们一直没讲，但我们还是开始分享它们了。
SciShow After Hours is a podcast that is not for kids because of that, but we are very excited about it.
SciShow After Hours是用于此目的的一个播客，它不是为孩子们准备的，我们对于它的推出感到非常兴奋。
If you want to listen to the first episodes and support SciShow along the way, you can go to patreon.com/scishow.
如果你想收听第一季并支持科学秀节目，可以访问patreon.com/scishow。
