很多經(jīng)歷青春期的少男少女都曾感到莫名的情緒在體內(nèi)躁動(dòng)，甚至有些人會(huì)一時(shí)沖動(dòng)而做出離經(jīng)叛道的事。這是因?yàn)榍嗌倌晔巧眢w趨于成熟，而大腦發(fā)育沒有跟上的一個(gè)時(shí)期。學(xué)者表示，對(duì)于青少年面臨的獨(dú)特健康挑戰(zhàn)，我們的了解還遠(yuǎn)遠(yuǎn)不夠，能做的也還有很多。

Whatever their foibles — door-slamming, grunting, excessive Snapchatting — teenagers are right about one thing: nobody understands them. This umbra of non-comprehension takes in not just parents, but doctors, psychologists, neuroscientists, social scientists, legal experts and educators.

不管他們有什么怪癖(摔門、不好好說話、把過多的時(shí)間花在Snapchat上)，少男少女們有一點(diǎn)是正確的：沒有人理解他們。不理解他們的不只是父母，還有醫(yī)生、心理學(xué)家、神經(jīng)學(xué)家、社會(huì)學(xué)家、法律專家和教育者。

There is surprisingly scant scientific research about the hazy period between childhood and adulthood in which adolescents exist. As an editorial in the journal Nature pointed out this month: “A modern healthcare system without a focus on the unique challenges of paediatrics or geriatrics would be unthinkable, yet there is no similar effort on behalf of adolescents.”

有關(guān)青少年所處的介于童年和成年之間這段模糊時(shí)期的科學(xué)研究出奇地匱乏。正如《自然》(Nature)雜志不久前的一篇社評(píng)指出的那樣：“難以想象一個(gè)現(xiàn)代醫(yī)療體系會(huì)不關(guān)注兒童或老年人所帶來的獨(dú)特挑戰(zhàn)，但青少年沒有得到類似的關(guān)注。”

The term adolescence stems from the Latin adolescere, meaning “to grow up” but, in many other contexts, it eludes easy definition. The World Health Organization puts adolescence between the ages of 10 and 19, with other categories jostling within that complex territory. The UN defines a youth as aged 15-24, a genre overlapping with “child” (under 18) and the generic “young people” (10-24).

“青少年”這個(gè)詞來源于拉丁語adolescere，意思是“成長”，但在很多其他語境下，它不容易定義。世界衛(wèi)生組織(WHO)把青少年定義為10至19歲，但涵蓋這個(gè)復(fù)雜年齡區(qū)間的還有其他分類。聯(lián)合國(UN)把青年定義為15歲至24歲，這與兒童(18歲以下)以及泛指的“年輕人”(10至24歲)重疊。

It should not surprise us, then, that there is great variation the world over — and even within countries — in the ages at which the young are entrusted with making adult decisions. Laurence Steinberg, a psychology professor, writes: “A society that tries 12-year-olds who commit serious crimes as adults because they’re mature enough to ‘know better’ but prohibits 20-year-olds from buying alcohol because they are too immature to handle it, is deeply confused about how to treat people in this age range.”

因此，我們對(duì)此就不應(yīng)感到意外了：全世界(甚至各國內(nèi)部)對(duì)于年輕人有能力做出成人決定的最低年齡界定存在巨大差異。心理學(xué)教授勞倫斯?斯坦伯格(Laurence Steinberg)寫道：“我們把一位犯下嚴(yán)重罪行的12歲年輕人當(dāng)作成年人來審訊，因?yàn)樗麄円炎銐虺墒�，�?yīng)該‘知道什么事情不能做’了;與此同時(shí)，我們禁止20歲的人買酒，因?yàn)樗麄冞�不夠成熟，無法駕馭酒精：這樣一個(gè)社會(huì)對(duì)于如何對(duì)待這個(gè)年齡區(qū)間的人是深感困惑的。”

Biology provides an obvious pointer. Adolescence is thought to begin with the onset of puberty (sexual development), but patterns of puberty vary around the world — and within countries — over time. One study shows that in the mid-19th century, girls in developed countries had their first period at about 15 or 16 years old. By 2000, this had dropped to below 13, a trend that has been attributed to better nutrition and healthcare. Puberty also occurs earlier in boys. Childhood obesity is thought to be an accelerating factor.

生物學(xué)提供了明顯的指標(biāo)。通常認(rèn)為，青春期(性發(fā)育期)開始時(shí)，兒童就成為了青少年，但發(fā)育的規(guī)律在全球(以及國家內(nèi)部)各有不同。一項(xiàng)研究顯示，19世紀(jì)中葉，發(fā)達(dá)國家女孩的初次月經(jīng)年齡大約為15或16歲。到2000年，這個(gè)年齡降至13歲以下，這一趨勢(shì)要?dú)w因于營養(yǎng)與醫(yī)療的改善。男孩的青春期也提前出現(xiàn)。據(jù)信，兒童肥胖是導(dǎo)致這種情況的一個(gè)因素。

Flowering bodies, however, are governed by childish brains. Prof Steinberg points out that the young brain continues maturing into the mid-20s. Neurodevelopmental changes depend partly on hormones and can drive pleasure-seeking, risky and impulsive behaviour. Accordingly, Professor Steinberg extends adolescence’s dominion to between the ages of 10 and 25.

然而，正在成熟的身體由仍處于孩童階段的大腦控制著。斯坦伯格教授指出，大腦要到25歲左右才發(fā)育成熟。神經(jīng)發(fā)育變化在一定程度上取決于激素，這些變化還可能激發(fā)尋求快感、冒險(xiǎn)和沖動(dòng)的行為。因此，斯坦伯格教授將青少年的年齡區(qū)間延長為10歲至25歲。

By then, of course, young people are already notching up the social milestones of adulthood: driving, voting, working, living independently, enlisting in the military, drinking, buying guns, marrying and becoming parents. Society will have long sexualised them. And for the digitally connected, the mis-steps of youth are today captured, shared and archived in perpetuity. That collision of adolescent brains with adult norms might underlie some of the darker statistics relating to young people. The leading causes of adolescent death are, respectively, road accidents, HIV and suicide.

當(dāng)然，到那時(shí)，年輕人已經(jīng)在完成標(biāo)志著長大成人的一件件大事：駕車、投票、工作、獨(dú)立生活、參軍、飲酒、購買槍支、結(jié)婚和生子。社會(huì)應(yīng)該也早已讓他們具備了性別意識(shí)。對(duì)于成長于數(shù)字互聯(lián)時(shí)代的人們而言，年少時(shí)走錯(cuò)的路如今會(huì)被記錄、分享并永遠(yuǎn)儲(chǔ)存下來。青少年的大腦與成年人的規(guī)范之間的沖突，可能從根本上導(dǎo)致了一些與年輕人相關(guān)的較沉重的統(tǒng)計(jì)數(shù)據(jù)。青少年死亡的主要原因分別是交通事故、艾滋病和自殺。

Adolescent health also deserves specific contemplation because the habits of youth can become the millstones of adulthood: teens who smoke cannabis or nicotine, or who abuse alcohol, often become hooked for life. Mental health issues tend to surface early in adulthood but afflicted adolescents are mostly diagnosed on the basis of adult criteria and treated with drugs intended for older patients. When it comes to understanding adolescents, it is adults who need to grow up.

青少年健康值得特別深思，還因?yàn)槟晟贂r(shí)的習(xí)慣可能會(huì)成為成年后的負(fù)擔(dān)：抽大麻、抽煙或酗酒的青少年通常會(huì)終身成癮。心理健康問題往往很早就有跡象，但青少年患者大多是根據(jù)成人標(biāo)準(zhǔn)接受診斷的，治療所使用的藥物也是原本針對(duì)年紀(jì)較大患者的。在了解青少年方面，需要成長的是成年人。