players of sports and recreational activities

運動和休閒活動

receive between 2.5 and 4 million concussions.

會產生約二百五到四百萬的腦震盪病患

How dangerous are all those concussions?

這些腦震蕩到底有多危險？

The answer is complicated,

這個問題答案相當的複雜

and lies in how the brain responds when something strikes it.

跟據大腦如何回應當時的撞擊

The brain is made of soft fatty tissue, with a consistency something like jello.

大腦是由柔軟的脂肪組織和像是果凍的黏稠液體所組成的

Inside its protective membranes and the skull's hard casing,

在它的保護膜和頭蓋骨內

this delicate organ is usually well-shielded.

這個脆弱的組織通常是被保護的很好

But a sudden jolt can make the brain shift

但是突然一晃腦袋可能會移位

and bump against the skull's hard interior,

和碰撞到頭蓋骨內側

and unlike jello, the brain's tissue isn't uniform.

不像果凍，大腦的組織不是均勻的

It's made of a vast network of 90 billion neurons,

它由廣闊網路的九百億條神經所組成

which relay signals through their long axons to communicate throughout the brain

腦神經轉達神經信息通過它們的長軸突讓通訊遍及大腦

and control our bodies.

才能控制我們的身體

This spindly structure makes them very fragile

這個外表上單薄的結構使得他們他們非常容易損壞

so that when impacted, neurons will stretch and even tear.

所以當受到衝擊，神經元會伸縮和甚至撕裂

That not only disrupts their ability to communicate

這不僅會干擾它們的通訊能力

but as destroyed axons begin to degenerate,

這不僅會干擾它們的通訊能力

they also release toxins causing the death of other neurons, too.

他們會釋放毒素，造成其它的神經元也一起死亡

This combination of events causes a concussion.

這些事件的組合造成腦震盪

The damage can manifest in many different ways

這些傷害能夠很明顯，有許多不同的呈現方式

including blackout,

包括暫時的意識喪失

headache,

頭痛

blurry vision,

視力模糊

balance problems,

失去平衡

altered mood and behavior,

改變心情和行為

problems with memory, thinking, and sleeping,

記憶、思考和睡眠出現問題

and the onset of anxiety and depression.

然後開始焦慮和沮喪

Every brain is different,

每顆腦袋都不一樣

which explains why people's experiences of concussions vary so widely.

這說明了為何人們經歷到的腦震盪如此不同

Luckily, the majority of concussions fully heal

幸運地，大多數的腦震盪都會痊癒

and symptoms disappear within a matter of days or weeks.

在數天或數週症狀會消失

Lots of rest and a gradual return to activity

多休息和逐步回復活動

allows the brain to heal itself.

能讓腦袋自我修復

On the subject of rest,

至於休息這件事

many people have heard that you're not supposed to sleep

大多數的人們所相信的是「你不應該去睡覺」

shortly after receiving a concussion because you might slip into a coma.

受到腦震盪後去睡覺可能會陷入昏迷

That's a myth.

無稽之談

So long as doctors aren't concerned there may also be a more severe brain injury,

常久以來，醫生們不擔心睡覺可能會讓大腦受到更嚴重的傷害

like a brain bleed,

像腦出血

there's no documented problem with going to sleep after a concussion.

目前沒有文件指出受到腦震盪後跑去睡覺有問題

Sometimes, victims of concussion can experience something

有些時候，腦震盪受害者會經歷一些

called post-concussion syndrome, or PCS.

稱為腦震盪後症狀也就是 PCS

People with PCS may experience constant headaches,

得到腦震盪症候群的人可能會經歷持續的頭痛

learning difficulties,

學習障礙

and behavioral symptoms that even affect their personal relationships

行為症狀甚至去影響他們的人際關係

for months or years after the injury.

在發生傷害後，持續數個月或數年

Trying to play through a concussion, even for only a few minutes,

若腦震盪後繼續活動就算只有數分鐘

or returning to sports too soon after a concussion,

或太快回去運動

makes it more likely to develop PCS.

使得它可能發展成為腦震盪症候群

In some cases, a concussion can be hard to diagnose

在一些案例，腦震盪可能很難診斷出來

because the symptoms unfold slowly over time.

因為症狀不是一直持續

That's often true of subconcussive impacts

這時常發生於輕微腦部撞擊

which result from lower impact jolts to the head

這種對腦部撞擊晃動比較輕

than those that cause concussions.

比起引起腦震盪的撞擊

This category of injury doesn't cause noticable symptoms right away,

這種傷害屬於不會產生立即可以注意到的

but can lead to severe degenerative brain diseases over time

但是隨著時間，這可以導致嚴重的腦部退化疾病

if it happens repeatedly.

如果它重複的發生的話

Take soccer players, who are known for repeatedly heading soccer balls.

以足球員來說，他們不斷的頂球

Using a technique called Diffusion Tensor Imaging,

使用「擴散張量影像」的技術

we're beginning to find out what effect that has on the brain.

才能開始找出腦震盪對大腦的影響

This method allows scientists to find large axon bundles

這個方法讓科學家找出大軸突束

and see how milder blows might alter them structurally.

並觀測多少的輕微撞擊可能會造成結構上的改變

In 2013, researchers using this technique discovered

在2013年，研究員使用這個技術發現

that athletes who had headed the ball most,

那些最常使用頭部頂球的運動員們

about 1,800 times a year,

大約每年一千八百次

had damaged the structural integrity of their axon bundles.

它們的軸突束整體結構已經受到傷害

The damage was similar to how a rope will fail

這種傷害有點類似，繩子斷掉的情況

when the individual fibers start to fray.

一旦繩子中的纖維開始磨損

Those players also performed worse on short-term memory tests,

這些運動員的短期記憶測試表現也較差

so even though no one suffered full-blown concussions,

所以儘管沒有人受到完全腦震盪

these subconcussive hits added up to measurable damage over time.

這些輕微撞擊隨著時間累積傷害

In fact, researchers know that an overload of subconcussive hits

事實上，研究員已經知道腦部受到過多輕微撞擊

is linked to a degenerative brain disease known as Chronic Traumatic Encephalopathy,

與一種腦袋退化疾病有所關聯，就是「慢性創傷腦病變」

or CTE.

或稱 CTE

People with CTE suffer from changes in their mood and behavior

CTE 患者的心情和行為會出現變化

that begin appearing in their 30s or 40s

於三十歲、四十歲開始出現症狀

followed by problems with thinking and memory

症狀有思考和記憶出現問題

that can, in some cases, even result in dementia.

在某些案例，這甚至會導致失智症

The culprit is a protein called Tau.

凶手就是 Tau 蛋白質

Usually, Tau proteins support tiny tubes inside our axons called microtubules.

通常 Tau 蛋白質會支撐我們軸突內的微管

It's thought that repeated subconcussive hits damage the microtubules,

CTE 可以想成不斷重複輕微撞擊去傷害微管

causing the Tau proteins to dislodge and clump together.

導致 Tau 蛋白質脫離並結塊

The clumps disrupt transport and communication along the neuron

結塊會中斷神經元的訊息通訊能力

and drive the breakdown of connections within the brain.

和破壞腦部神經元之間的連結

Once the Tau proteins start clumping together,

當 Tau 蛋白質開始結塊

they cause more clumps to form

他們會形成更多

and continue to spread throughout the brain,

並繼續蔓延遍布腦部

even after head impacts have stopped.

在頭部撞擊停止後，仍然一直持續著

The data show that at least among football players,

數據顯示至少對美式足球員來說

between 50 and 80% of concussions go unreported and untreated.

大約有百分之五十到八十的腦震盪沒有回報和接受治療

Sometimes that's because it's hard to tell

有時候是因為，它比較難以分辨

a concussion has occurred in the first place.

在剛發生腦震盪時

But it's also often due to pressure or a desire to keep going

但也時常是因為想要繼續打下去的壓力或欲望

despite the fact that something's wrong.

儘管實際情況已經有些不對勁

This doesn't just undermine recovery.

這不只會破壞復原能力

It's also dangerous.

同時也很危險

Our brains aren't invincible.

我們的腦不是無敵的

They still need us to shield them from harm

仍然需要我們去保護他們不受到傷害

and help them undo damage once it's been done.

和當發生傷害時的回復