How stress affects your brain - Madhumita Murgia

譯者: Emilia Wei 審譯者: Wen Peng

Are you sleeping restlessly,

你是否睡眠品質很差

feeling irritable or moody,

情緒焦躁易怒

forgetting little things,

容易健忘

and feeling overwhelmed and isolated?

或常感到孤獨沮喪?

Don't worry. We've all been there.

別擔心，大家都有這種經驗

You're probably just stressed out.

你可能只是壓力太大了

Stress isn't always a bad thing.

壓力也是有好處的

It can be handy for a burst of extra energy and focus,

能瞬間提升爆發力和專注力

like when you're playing a competitive sport,

這些能力在競賽時不可或缺

or have to speak in public.

在演講時也會派上用場

But when its continuous,

但如果壓力長期存在

the kind most of us face day in and day out,

變成每天的負擔

it actually begins to change your brain.

大腦就會開始改變

Chronic stress,

長期壓力過大

like being overworked or having arguments at home,

如工作過度

或常和家人起爭執

can affect brain size,

會影響大腦的大小

its structure,

結構

and how it functions,

甚至運作的方式

right down to the level of your genes.

更會影響基因

Stress begins with something called

壓力由HPA軸控制

the hypothalamus pituitary adrenal axis,

即「下視丘-腦垂腺-腎上腺軸」

a series of interactions

腦內的腺體及腎上腺

between endocrine glands in the brain and on the kidney,

進行一連串交互作用

which controls your body's reaction to stress.

共同控制身體的壓力反應

When your brain detects a stressful situation,

當大腦偵測到令人緊張的環境

your HPA axis is instantly activated

HPA軸便立即開始運作

and releases a hormone called cortisol, which primes your body for instant action.

釋放一種叫做可體松的荷爾蒙

使身體進入備戰狀態

But high levels of cortisol over long periods of time

但長期可體松含量過高

wreak havoc on your brain.

會嚴重傷害腦部

For example, chronic stress increases the activity level

長期壓力下，在腦部杏仁核中

神經元連結數和活化度都會增加

and number of neural connections in the amygdala,

your brain's fear center.

而杏仁核正是情緒中樞

And as levels of cortisol rise,

隨著可體松濃度升高

electric signals in your hippocampus,

海馬迴的神經網也會受到破壞

the part of the brain associated with learning, memories, and stress control,

學習、記憶、壓力調適等能力

deteriorate.

都會跟著變差

海馬迴也會抑制HPA軸的運作

The hippocampus also inhibits the activity of the HPA axis,

so when it weakens,

所以海馬迴受損

so does your ability to control your stress.

控制壓力的能力也跟著下降

That's not all, though.

除此之外

Cortisol can literally cause your brain to shrink in size.

可體松還會造成大腦萎縮

Too much of it results in the loss of synaptic connections between neurons

也會使神經元的軸突連結減少

and the shrinking of your prefrontal cortex,

或造成腦前額葉萎縮

the part of your brain the regulates behaviors like concentration,

這個區域主管我們的專注力

decision-making,

決策力

judgement,

判斷力

and social interaction.

和社交行為

It also leads to fewer new brain cells being made in the hippocampus.

另外，海馬迴的新生細胞也會減少

This means chronic stress might make it harder for you to learn

學習和記憶因此變得更困難

and remember things,

and also set the stage for more serious mental problems,

還可能導致更嚴重的心理疾病

like depression and eventually Alzheimer's disease.

如憂鬱症

甚至是阿茲海默症

The effects of stress may filter right down to your brain's DNA.

壓力還會影響腦部基因

An experiment showed

一項實驗顯示

that the amount of nurturing a mother rat provides its newborn baby

母老鼠對新生寶寶的照顧

plays a part in determining how that baby responds to stress later in life.

大大影響老鼠寶寶

未來面對壓力的能力

The pups of nurturing moms turned out less sensitive to stress

感受滿滿母愛的小老鼠

會對壓力較不敏感

because their brains developed more cortisol receptors,

牠們腦部有較多可體松受體

which stick to cortisol and dampen the stress response.

能接收可體松並抑制壓力反應

The pups of negligent moms had the opposite outcome,

與媽媽較疏離的小老鼠則相反

and so became more sensitive to stress throughout life.

終其一生都對壓力很敏感

These are considered epigenetic changes,

我們稱這些改變為「表徵遺傳」

meaning that they effect which genes are expressed

基因的表現改變了

without directly changing the genetic code.

但DNA序列不變

And these changes can be reversed if the moms are swapped.

把老鼠媽媽調換

就可消除基因表徵的改變

But there's a surprising result.

但還有項驚人的發現

The epigenetic changes caused by one single mother rat

一隻老鼠媽媽產生的影響

were passed down to many generations of rats after her.

將會代代相傳

In other words, the results of these actions were inheritable.

換句話說,這些變化是會遺傳的

It's not all bad news, though.

不過也別太悲觀

There are many ways to reverse what cortisol does to your stressed brain.

很多方法可以消除

可體松對大腦的影響

The most powerful weapons are exercise and meditation,

最有效的就是運動和冥想

which involves breathing deeply

這些活動讓你深呼吸

and being aware and focused on your surroundings.

並專注覺察周遭事物

Both of these activities decrease your stress

運動和冥想能減緩壓力

and increase the size of the hippocampus,

也會增大海馬迴

thereby improving your memory.

因此能增強記憶力

So don't feel defeated by the pressures of daily life.

所以別因為壓力而沮喪

Get in control of your stress before it takes control of you.

在壓力控制你之前

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