爲什麼男性禿頭都禿成一個樣?心疼男神們的髮際線

Hair loss is complicated, and scientists are still trying to work out the bugs on why and how it happens. Pretty much all of them agree that Male pattern baldness (MPB) is usually genetic. Typically, loss begins above both temples, receding until a characteristic "M" pattern emerges. Often, but not always, the crown also starts to lose hair.

脫髮是一個複雜的問題，科學家們還在摸索其中的因果。多數科學家認爲，男性型脫髮跟基因有關。一般來說，男性型脫髮會從兩側太陽穴上方開始，直到出現典型的M形髮際線。通常頭頂也會開始脫髮，但並非所有人都是如此。

This is likely due to changes in how the body processes certain androgens, the male sex hormones. In fact, men with MPD actually inherited a genetic sensitivity to the androgen dihydrotestosterone (DHT). This sensitivity causes hair follicles to miniaturize, which shortens their life span and eventually leads them to stop growing hair. The areas most often affected by miniaturization are the crown and frontal hairline.

這可能與身體處理某些雄性激素的方式有關。事實上，患有雄性禿的男性繼承了對雄激素二輕睾酮的遺傳易感性，從而導致毛囊縮小、毛囊壽命縮短，最後無法再長出頭髮。而毛囊最容易縮小的部位就是頭頂和前額髮際線。

"Many men have frontal hairline recession only. Others will have thinning in the vertex (crown) of the scalp. Many times, both happen at the same time," says Dr. Amy McMichael with the Wake Forest Department of Dermatology in an email interview. "The order is predicted by genetics and each person has slightly different genetics that determine when hair will begin to thin and how severe hair loss will be."

維克福斯特皮膚科醫生艾米?麥克邁克爾在接受郵件採訪時表示：“許多男性只出現了髮際線升高的問題。也有男性是頭頂脫髮。但大多數時候，這兩者是同時發生的。脫髮順序是由基因決定的，每個人的基因都有些微不同，因此開始脫髮的時間和脫髮嚴重程度也不一樣。”

The rest of the hair on the head is made of hardier stuff, apparently. The reason why men do not lose hair in the posterior scalp is that these follicles are genetically programmed to be stem cells and do not shed. This is why hair transplants harvest the hair from the back of the scalp.

頭部其他地方的頭髮似乎更加強健。男性頭部後方之所以不會脫髮，是因爲基因決定這裏的毛囊由幹細胞組成，並不會脫髮。也正因如此，植髮時移植的是後腦部位的頭髮。

Scientists are using this knowledge to develop more effective treatments to slow or stop hair loss. Currently, only two treatments are approved by the U.S. Food & Drug Administration. Minoxidil (brand name Rogaine) is applied topically, directly to the scalp to stimulate hair follicles. It has shown some success at slowing hair loss, even helping to re-grow hair. The other option is Finasteride (Propecia), which is taken orally to limit the production of the disruptive androgen DHT, which slows hair loss and promotes hair growth.

科學家們正在利用這一點研究延緩或根治脫髮的更有效療法。目前，獲得美國食品藥品監督管理局批准的只有兩種藥物。米諾地爾（品牌名落健）局部直接外用於頭皮刺激毛囊，能夠在一定程度上延緩脫髮速度，甚至促進頭髮再生長。另一種藥物是非那雄胺（保法止），通過口服抑制雄性激素二氫睾酮的分泌，以延緩脫髮並促進頭髮再生。