Why do some people go bald? - Sarthak Sinha

為什麼有些人會變禿？- 沙塔克‧辛哈

譯者: Sherl H 審譯者: Harry Chen

What do Charles Darwin, Michael Jordan, and Yoda have in common?

達爾文、喬登和尤達有何共通點呢？

They, like many other historical and fictive individuals, are bald,

就像許多歷史上和小說裡的 人物 －他們都是禿頭的！

in some cases by their own choice.

少數的案例是自身的抉擇

For centuries, a shining dome has been a symbol of intelligence,

好幾百年來光滑的禿頂 一直是智慧的象徵

but despite this, many balding people still wish their hair would return.

不過儘管如此許多正在禿頭的人 還是希望頭髮會長回來

Scientists have long pondered,

科學家們已經苦思許久

"Why do some people lose their hair, and how can we bring it back?"

「為什麼有些人會沒了頭髮？ 以及該如何把頭髮長回來？」

The full-headed among us have about 100,000 to 150,000 hairs on our scalps,

一頭茂盛的髮量在頭皮上約有 100,000 到 150,000 根頭髮

and scientists have discovered two things about this dense thicket.

而關於這茂密的髮林 科學家們發現了兩件事

Firstly, the sprouting hair we see is mostly made up of keratin,

首先我們所看到不斷長出的 頭髮主要是由「角蛋白」所構成

the protein leftover from dead cells that are forced upwards

從死去的細胞而來的蛋白質剩料

當新細胞在其下方生長時受力向上冒出

as new cells grow beneath them.

Secondly, the structures that drive hair growth

第二、驅使頭髮生長的構造叫「毛囊 」

are called hair follicles,

a network of complex organs that forms before we're born,

早在我們出生前所形成之 複雜網絡的身體部位

and grows hair in an everlasting cycle.

並且在永不止息的循環下長頭髮

This cycle has three main phases.

這循環有三個主要的階段

The first is anagen, the growth phase,

第一階段是「生長期」

which up to 90% of your hair follicles are experiencing right now,

你們多達 90% 的毛囊 正在歷經這個階段

causing them to push up hair at a rate of one centimeter per month.

造成它們將頭髮以每個月 1 公分的速率往上推出

Anagen can last for two to seven years, depending on your genes.

生長期取決於你的基因 能夠持續 2 到 7 年

After this productive period,

在這個生意盎然的階段之後

signals within the skin instruct some follicles to enter a new phase

皮膚內的訊息會指示部份毛囊

進入叫做「衰退期」的新階段

known as catagen, or the regressing stage,

causing hair follicles to shrink to a fraction of their original length.

造成毛囊萎縮成原先長度的一小部分

Catagen lasts for about two to three weeks

衰退期會維持大概 2 至 3 個星期

and cuts blood supply to the follicle, creating a club hair,

以及阻斷毛囊的血液供應 產生「杵狀髮」

meaning it's ready to be shed.

這表示著它做好準備要被脫落掉了

Finally, hairs enter telogen, the resting phase,

最後頭髮進入了「休止期」

which lasts for ten to twelve weeks,

這會維持 10 至 12 個星期

and affects about 5-15% of your scalp follicles.

並且影響到大約 5 到 15% 的頭皮毛囊

During telogen, up to 200 club hairs can be shed in a day,

在休止期一天能夠脫落 多達 200 根頭髮

which is quite normal.

這樣是稀鬆平常的事

Then, the growth cycle begins anew.

接著生長循環又重新來過

But not all heads are hairy,

不過並非每個人的頭全都毛髮茂密

and, in fact, some of them grow increasingly patchy over time

而且事實上有些人長期下來 因應身理上的變化

in response to bodily changes.

頭髮長得越來越稀少

95% of baldness in men can be attributed to male pattern baldness.

男性中 95% 的禿髮可以 被歸成「雄性禿」

Baldness is inherited,

禿頭是遺傳的

and in people with this condition,

有這種情形的人身上

follicles become incredibly sensitive to the effects of dihydrotestosterone,

毛囊對二氫睪固酮 － DHT 的作用 變得益加敏感的

a hormonal product made from testosterone.

那是一種從睪固酮素產生的賀爾蒙產物

DHT causes shrinkage in these overly sensitive follicles,

DHT 導致這些過度敏感的毛囊縮水

making hair shorter and wispier.

使得頭髮更短、更細弱

But loss isn't sudden.

但是掉髮不是一夕產生的

It happens gradually, along a metric known as the Norwood Scale,

它依循著諾伍德量表逐步地發生

which describes the severity of hair loss.

該量表指出掉髮的嚴重程度

First, hair recedes along the temples,

首先、髮線延著太陽穴消退

then hair on the crown begins to thin in a circular pattern.

接著頭頂的頭髮以圓形樣態開始變稀疏

At the highest rating on the scale,

在量表上的最高分級來說

these balding areas meet and expand dramatically,

這些光禿的區域驚人地相遇、擴展開

eventually leaving only a ring of sparse hair around the temples

最終只剩下頭頂外圍和後腦稀少的頭髮

and the back of the head.

Genetics isn't all that drives hair loss.

基因並不是驅使頭髮消失一切的原因

Long periods of stress can release signals that shock follicles

長期的壓力能夠釋放出打擊毛囊的訊息

and force them into the resting phase prematurely.

並迫使它們永遠地進入休止期

Some women experience this after childbirth.

有些婦女在產後會經歷這種狀況

Follicles might also lose the ability to go into anagen, the growth phase.

毛囊也可能失去進入生長期的能力

People going through chemotherapy treatment temporarily experience this.

接受化療的人會短暫性地經歷這種情形

But while balding may look permanent,

但是當禿頭也許看來是改變不了了

scientific investigation has revealed the opposite.

科學研究卻呈現出相反的一回事

Below the skin's surface,

在皮膚表皮下方長出頭髮的髮根 事實上還持續活著

the roots that give rise to our hair actually remain alive.

Using this knowledge,

運用這項知識科學家們 開發出藥物來縮短休止期

scientists have developed drugs that shorten the resting phase,

and force follicles into anagen.

並且迫使毛囊進入生長期

Other drugs combat male pattern baldness

其他打擊雄性禿的藥品

by blocking the conversion of testosterone to DHT

透過阻斷睪固酮轉變成 DHT

so that it doesn't affect those sensitive follicles.

所以它不會影響到那些敏感的毛囊

Stem cells also play a role in regulating the growth cycle,

幹細胞在管控生長週期上 也扮演了重要的角色

and so scientists are investigating whether they can manipulate

所以科學家們正在研究

到底能否操控幹細胞的活動 來促使毛囊再次啟動長出頭髮嗎？

the activity of these cells to encourage follicles to start producing hair again.

And in the meantime,

當科學家還在增益他們的 頭髮回春辦法時

while scientists hone their hair-reviving methods,

anyone going bald, or considering baldness,

際此同時任何正在禿頭 或是認為是禿頭的人

can remember that they're in great company.

能記好來「同病相憐者大有人在！」