The Science Behind How Sickness Shapes Your Mood | Keely Muscatell | TED

譯者: Lilian Chiu 審譯者: 麗玲 辛

Alright, I'd like you to take a moment.

好，我想請各位花點時間，

Think about a time when you were recently sick.

想想你最近生病的時候。

Try specifically to think of a time when,

更具體來說，試著去想這樣的時候：

even though you weren't feeling all that great,

即使你感覺沒有很好，

you still felt well enough to get up out of bed,

你還是起得了床，

go about your day.

可以展開那一天。

OK, what was your mood like?

好，那時你的心情如何？

Did you feel a little sad or depressed?

你會感到有點悲傷或憂鬱嗎？

What types of social interactions did you want to have?

你希望有什麼樣的社交互動？

Would you have wanted to go to a cocktail party full of strangers

你會想出席一個滿是 陌生人的雞尾酒派對嗎？

or out on a first date?

或去見初次約會的對象？

I'm a psychology professor

我是心理學教授，

在北卡羅萊納大學教堂山分校

at the University of North Carolina at Chapel Hill,

and for the past 15 years,

任職了十五年，

I've been studying the interconnections between physiological changes

我一直在研究這兩者之間的關聯：

生病時體內發生的生理改變

happening in the body during sickness

and psychological and social well-being.

以及心理和社會幸福感。

Specifically my lab studies social psychoneuroimmunology,

具體來說，我的實驗室是在探究

社會心理神經免疫學，

which is a mouthful to say,

唸起來很拗口，

and is a field of research that's dedicated

這個研究領域旨在發掘 以下因素的交互作用：

to discovering interactions between our social experiences,

我們的社會經驗、

心理過程，以及免疫系統。

psychological processes and the immune system.

Today, I want to tell you about some research showing

今天，我想告訴各位，有研究顯示，

that the same physiological changes happening in your body

在你生病時造成身體症狀的

that cause the physical symptoms you have when you're sick,

那些體內生理改變，

are also shaping your mood and your social behavior.

也會影響你的心情和你的社會行為。

In other words, changes in the immune system

換言之，免疫系統上的改變 會向大腦發出訊號，

can signal to the brain to cause us to think,

造成我們有不同的想法、 感受和行為。

feel and act differently.

And not only that, but also our social experiences can cause changes

不儘如此，我們的社會經驗

也會造成免疫系統的改變。

in our immune systems.

So purely psychological things happening in our brains

因此，我們大腦中的純心理活動

can cause the immune system to ramp up or ramp down.

可能會造成免疫系統增強或減弱。

Because of that, we can get caught in these vicious cycles

因為如此，我們可能會 陷入惡性循環中，

where our psychological experiences can cause changes in our immune system,

在這些循環中，我們的心理經驗 可能會造成免疫系統改變，

and those immunological shifts can cause changes

而這些免疫轉變可能會 造成我們心理經驗的變化。

to our psychological experiences.

Now the component of the immune system

大部分心理神經免疫研究 最強調的免疫系統要素

that most research in psycho- neuroimmunology focuses on

is the inflammatory response or inflammation.

是發炎反應或炎症。

The inflammatory response is your immune system's

發炎反應是免疫系統

first line of defense against injury or infection,

遇到受傷或感染時的第一道防線。

and it's coordinated by these molecules

負責協調發炎反應的分子叫做

that are called pro-inflammatory cytokines.

前發炎細胞激素。

You can think of cytokines as sort of the chemical messengers

各位可以把細胞激素想成 免疫系統的化學信差。

of the immune system.

So they're out there right now, swimming through your bloodstream.

它們現在就在你的血液中游動。

And if an immune cell finds something weird or out of the ordinary,

如果有免疫細胞發現 奇怪或不尋常的東西，

they'll tell those cytokines to signal to other immune cells

它們會叫細胞激素 去告訴其他免疫細胞，

to come and check it out.

過來看看是怎麼回事。

So if you think about a time you've had a paper cut,

想想你被紙割傷的時候，

you may have noticed that the area around the cut swells,

你可能會注意到傷口的周圍

腫起來、發紅，有灼熱感。

it turns red, it heats up.

That's the inflammatory response in action.

那就是發炎反應正在起作用了。

And those symptoms are caused by your cytokines doing their job,

會出現那些症狀，是因為 你的細胞激素盡了職責，

sending out signals to other immune cells to come and heal the cut.

發送訊號給其他免疫細胞， 叫它們來治癒割傷。

The same thing happens if your immune cells find a virus

如果你的免疫細胞 在體內發現病毒或細菌，

也會有同樣的現象發生。

or a bacteria in the body.

They send out cytokines to signal to other immune cells

它們會派細胞激素 發送訊號給其他免疫細胞，

to come and try and eliminate the pathogen.

要它們過來消滅病原體。

Now in doing this, cytokines cause

細胞激素的這個做法就會造成

the physical symptoms we commonly have when we're sick.

我們生病時通常會出現的身體症狀，

Things like fever and achiness and fatigue.

比如發燒、酸痛，和虛弱。

So even though we usually think of those symptoms as being caused by a virus

雖然我們通常以為造成這些症狀的

or a bacteria itself,

是病毒或細菌本身，

they're actually caused by our own immune systems

其實真正的成因是 免疫系統啟動，試圖消滅病原體。

activating to try to eliminate the pathogen.

But in addition to those physical symptoms,

但，除了那些身體症狀之外，

decades of research,

數十年的動物和人體研究

in both animals and humans,

明顯顯示

clearly shows that cytokines also cause changes to our mood

細胞激素也會造成我們的心情改變，

and to our social behavior.

以及我們的社會行為改變。

So inflammation in the body can signal to the brain

因此，身體發炎時， 會發訊號給大腦，

to cause us to feel down,

造成我們心情低落、

depressed and even hopeless.

憂鬱，甚至覺得無望。

Inflammation can also make us want to socially withdraw from other people

炎症也會讓我們想要 遠離社交，遠離其他人，

to avoid interacting with individuals in our social networks.

避免在社交網絡中和別人互動。

So this research shows the powerful influence that the immune system can have

因此，這些研究顯示 免疫系統有很強大的影響力，

on our mood and on our social behavior.

會影響我們的心情以及社會行為。

Changes in inflammation in the body

體內若有炎症的變化，

can signal to the brain to cause us to feel depressed and even lonely.

就會向大腦發出訊號， 造成我們感到憂鬱，

甚至寂寞。

OK, so you may be wondering,

各位可能在納悶，

why on Earth would your body do this?

我們的身體幹嘛這樣做啊？

Why would you want your immune system to be able to manipulate your brain

為什麼要讓我們的免疫系統 操縱我們的大腦，

and cause you to feel sad and distant from other people in your life?

導致我們感到悲傷， 並疏遠生活中的其他人？

While we can't know for sure why this happens,

我們無法確定這背後的原因，

evolutionary theory provides some good food for thought.

但演化理論提供了 一些引人深思的可能性。

The fact is,

事實是，

revving up and running the immune system takes a lot of energy.

免疫系統的啟動和運行 會耗費大量的能量，

Getting cytokines to swim through the bloodstream

讓細胞激素在血液中游動 以及發送訊號給免疫細胞

and send signals to immune cells takes calories.

都會消耗卡路里。

And what else takes calories?

還有什麼會消耗卡路里？

Pretty much everything.

幾乎做什麼都會。

Especially things like going out and seeking pleasurable experiences,

特別是比如出門去玩樂、

interacting with strangers

和陌生人互動，

and just generally moving about the world.

以及平常的四處走動。

So the theory is that the immune system is telling the brain to feel depressed

因此，理論是，

免疫系統讓大腦感到憂鬱，

and to withdraw from socializing

遠離社交活動，

because it wants you to stay at home and rest.

因為它想要你待在家裡休息。

And if things that would normally sound fun

平常聽起來會很有趣的事情，

just don't seem all that fun,

此時似乎也沒那麼有趣了。

and if interacting with other people seems exhausting

如果和他人互動似乎會很累人，

and maybe even a little threatening,

甚至有威脅性，

then we'll be less likely to do those things

我們就比較不會去做那些事，

and more likely to stay at home

比較有可能待在家裡，

and let our immune systems use our calories.

讓我們的免疫系統 使用我們的卡路里。

Now, of course, if this becomes prolonged and inflammation is elevated over weeks

當然，如果拖太久，

炎症持續數週，或甚至數年，

or even years,

that could have really terrible impacts on our well-being.

對我們的幸福感 可能會有很不好的影響。

But in the short term,

但，就短期來說，

we think of this immune-to-brain signaling as adaptive.

我們認為免疫系統向大腦 發送訊號的機制是一種適應。

Your immune system is basically good at knowing when it would be a good idea

基本上，你的免疫系統 很擅長判斷何時是好時機，

適合你出門去 和世界及人們進行互動。

for you to be out interacting with the world and the people in it,

and when it would be better to just stay at home.

以及何時還是待在家就好。

But it turns out, the influence of inflammation on our social lives

但結果發現，

炎症對我們社交生活的影響 沒有那麼簡單，

isn't as simple as always making us feel more disconnected

並不見得都只是讓我們感到 比較不想與人連結，

and socially withdrawn.

想遠離社交。

One of the most important discoveries

近期，在這個研究領域中 最重要的發現之一

that we've made in this area of research recently

is that inflammation might actually make us more motivated

是炎症可能會讓我們更有動力

to seek some social interactions,

去尋求某些社交互動，

specifically those with the people who we're closest to.

特別是和我們親近的人互動。

So it’s not that inflammation makes us less social across the board,

因此，炎症並不是讓我們 在各方面都變得不想社交，

it may just make us more selective about who we want to socialize with.

它只是讓我們變得 對社交對象更挑剔。

To discover this, my colleagues and I ran an experiment.

為了探究這個現象， 我和我的同事做了一項實驗，

We asked participants in our study

我們請研究的受試者 傳數位照片給我們，

to send us digital photographs of someone who they could go to

他們需要協助或支持時 會去求助的對象的照片。

if they needed help or support.

As you would expect, people sent us photos of their romantic partners,

如大家預期，受試者傳來的 照片是他們的愛情伴侶、

their closest friends and their family.

最好的朋友，和他們的家人。

Then we had our participants view those images of their support figure

接著，我們請受試者觀看 他們的支持者的影像，

while we tracked their brain activity using MRI scanning.

同時我們用磁振造影掃描 來追蹤他們的大腦活動。

Now, critically, prior to the MRI scans,

重點是，在磁振造影掃描之前，

we exposed a random half of the participants in our study

我們隨機選出一半的受試者， 讓他們接觸一種細菌，

to a bacteria which cause levels of inflammation in the body to increase.

造成他們體內的發炎反應增加。

The other half just had normal, low levels of inflammation.

另一半受試者則是只有 正常的低度發炎反應。

And what we found is that for the people who we exposed to that bacteria,

我們的發現是，

接觸到細菌的那些人

體內有大量細胞激素，

who had lots of cytokines in their body,

他們大腦中和獎勵相關的區域 展現出比較大量的活動，

they actually showed more activity in a reward-related region of the brain,

called the ventral striatum,

這個區域叫腹側紋狀體，

when they viewed images of their support figures

在他們觀看支持者的 影像時就會活躍起來。

relative to the people who had low levels of inflammation.

相較之下，發炎反應較低的人 此區域就沒那麼活躍。

So what this suggests

這項發現意味著，

is that while inflammation might make social interactions with strangers

雖然炎症會讓「與陌生人 進行社會互動」

seem less rewarding,

顯得不那麼有吸引力，

it doesn't necessarily make all social interactions seem less rewarding.

它不見得會讓所有的社交互動 都顯得沒有價值。

In fact, inflammation may make us more motivated to seek interactions

事實上，炎症會讓我們更有動力

去找能提供我們慰藉 或關心的人，進行互動，

with people who could provide us with comfort or care.

Those who could be a shortcut to chicken soup.

也就是可以馬上帶來心靈雞湯的人。

But of course, it's not every day

但，當然，我們並不會每天都接觸到

that we come into contact with a virus or a bacteria,

病毒或細菌，或者有傷口，

or that we have a wound

that causes our levels of inflammation to increase.

而造成我們的發炎反應增加。

So how much of a day-to-day influence on our social lives

那麼，免疫系統對我們的社交生活

實際上會有多大的日常影響？

does the immune system actually have?

Research shows that the answer is a lot more than you might think.

研究顯示，答案遠超過你所想像的。

That's because one of the most robust findings

那是因為，在所有 心理神經免疫學研究中

in all of psychoneuroimmunology research

最穩固的發現之一

is that stress causes inflammation.

就是壓力會造成發炎。

So purely psychological things happening in the brain

所以，單純只是大腦中的心理因素

can cause increases in cytokines in the body.

就可能會造成體內的細胞激素增加。

This is true across species,

不同物種也有此現象，

from rodents to primates to humans.

從齧齒目動物， 到靈長類動物，到人類。

In my lab and in others across the globe,

我的實驗室及全球 一些其他的實驗室

we study the effects of stress on inflammation

在研究壓力對炎症的影響，

by asking people to come into the lab and give a ten-minute,

我們請受試者

到實驗室做一段十分鐘的即興演講，

off-the-cuff speech

about why they'd be a good candidate for their dream job.

談自己為什麼是 他們夢想工作的理想人選。

And then they have to do challenging mental math out loud.

接著他們要做很有挑戰性的 心算，得大聲說出來。

And they do this all in front of a panel of experts who's judging them.

而且，他們要在負責評鑑的 專家小組面前，完成上述任務。

Yeah, people report that this is stressful.

是的，受試者描述說 這過程壓力很大。

And critically,

重要的是，

in response to this psychologically stressful experience,

這段心理壓力很大的經歷 造成的反應是

we see that levels of cytokines in the body have increased.

可以看見體內的細胞激素增加。

Let's take a second and really appreciate that remarkable finding.

讓我們花點時間， 好好理解這個特別的發現。

In the absence of anything physically wrong with the body --

在身體沒有任何實體問題的情況下——

no viruses, no bacteria, no wounds --

沒有病毒，沒有細菌，沒有傷口——

a purely psychological stressor

一個單純心理面的壓力因子

is causing the inflammatory response to activate.

就能啟動發炎反應。

So it's not just that our immune systems are sending signals to our brain,

所以，不只是我們的免疫系統 會發送訊號給大腦，

but also our brains are sending signals to our immune systems

我們的大腦也會發送訊號 給免疫系統，

telling them to activate in response to stress that we encounter.

要求它們啟動， 以因應我們遇到的壓力。

OK, so now that you know

好，現在你知道了免疫系統 有非常活躍的社交生活，

that your immune system has this very active social life

and that your brain and your immune system are constantly communicating

且大腦和免疫系統經常在做溝通，

in ways that could make you feel depressed or lonely,

它們的溝通可能會 造成你感到憂鬱或寂寞，

what should you do?

那你該怎麼辦？

對我來說，

For me, knowing about the social life of the immune system

了解免疫系統的社交生活 改變了我的生活，

has changed my life,

in part because it gives me an explanation

部分原因是因為它讓我了解

for why I might feel physically crummy at the end of a stressful day,

為什麼在經過壓力很大的一天 之後，我身體上的感受會很差，

or why I might feel a little down

或為什麼當我身體不舒服時， 我的心情會有點低落

and disconnected from other people when I'm feeling physically unwell.

且不想和他人互動。

So, for example,

舉例來說，

the experience of giving this talk today has been really rewarding

今天來這裡演講的經歷非常有價值，

and also quite challenging.

也相當有挑戰性。

You might even say it was, at times, stressful.

甚至可以說，有時壓力挺大的。

And I'm sure you've had similar experiences in your lives.

我相信各位在自己的 人生中也有類似的經歷。

Maybe it was a difficult task you had to complete at work,

也許是在工作上必須要 完成一項困難的任務、

a confrontation with a spouse or a family member,

和配偶或家人對質，

or just some problem that cropped up in your life

或者就只是在生活上遇到 某種需要馬上設法解決的問題。

that you had to quickly figure out how to solve.

Based on what I've told you here today,

根據今天我在這裡分享的內容， 我希望各位就能預期

I hope you're predicting that in response to these stressful experiences,

自己對這些壓力經驗的反應，

we're likely to have high levels of inflammation in our bodies.

可能是體內會產生大量的發炎反應。

Our cytokines will have come out in full force

我們的細胞激素會傾巢而出，

in response to the stress we've experienced.

來因應我們遇到的壓力。

And because of that,

因此，

if we then feel exhausted

如果我們接著感到筋疲力盡，

and a bit like we've failed

且有點覺得自己搞砸了，

and we don't want to go anywhere or see anyone or do anything,

不想去任何地方、 見任何人，或做任何事，

and we just want to stay at home and relax on the couch

只想待在家裡，

和與我們最親近的人 在沙發上放鬆一下，

with the people who we're closest to,

we'll know why.

我們會知道背後的原因。

And because we know that those symptoms are likely just our immune systems

因為我們知道，那些症狀很可能 只是我們的免疫系統

telling our brains to feel depressed

告訴我們的大腦要感到憂鬱， 並遠離社交互動，

and to withdraw from social interactions

讓我們可以待在家裡 休息、放鬆，並恢復，

so that we stay at home to rest, relax and recuperate,

we don't have to agonize

我們就不必苦惱

over why we're maybe feeling a little down on ourselves,

自己為什麼會感到有點沮喪，

or a little distant from other people.

或對他人有距離感。

We can rest assured that

我們可以放心，知道

in the coming days,

過幾天，

we'll be feeling much more like ourselves again

我們就會覺得自己恢復正常了，

as our cytokine levels go back down.

等細胞激素降回正常標準就好。

So in the future,

因此，將來， 當你在生活中遇到壓力，

when you encounter stress in your life

and you feel those reins of inflammation start to take hold,

感受到炎症的控制開始發揮作用，

I hope you remember what I've told you here today.

我希望你能想起今天我分享的內容。

And you remind yourself that those symptoms you're experiencing,

你就可以提醒自己， 你所遇到的那些症狀

that's likely just your immune system

很可能只是你的免疫系統

doing its job,

在盡它的職責，

telling your brain to feel depressed and withdrawn

告訴你的大腦要感到憂鬱和退縮，

as evolution intended,

這只是演化而來的機制， 目的是確保你長期的健康。

to keep you healthy in the long term.

Thank you very much.

非常謝謝。

(Applause)

（掌聲）