大麻对你的大脑有害吗？ - 阿尼斯·巴吉：英语精读讲义

In 1970, marijuana was classified as a Schedule 1 drug in the United States, 文化背景

1970年，大麻在美国被列为附表一药物，

the strictest designation possible,

这是最严格的分类，

meaning it was completely illegal and had no recognized medical uses. 用詞

意味着它完全非法，且不具备公认的医疗用途。

For decades, this view persisted and set back research on the drug's mechanisms and effects. 短語動詞

几十年来，这种观点一直存在，阻碍了对该药物机制和效果的研究。

Today, marijuana's therapeutic benefits are widely acknowledged, 用詞

如今，大麻的治疗功效已被广泛认可，

and some nations have legalized medical use or are moving in that direction. 習語

一些国家已将医疗用途合法化，或正朝着这个方向发展。

But a growing recognition for marijuana's medical value doesn't answer the question: 表達脈絡

但人们对大麻医疗价值日益增长的认可，并没有回答这个问题：

Is recreational marijuana use bad for your brain? 用詞

娱乐性使用大麻会对你的大脑有害吗？

Marijuana acts on the body's cannabinoid system, 短語搭配

大麻作用于人体的内源性大麻素系统，

which has receptors all over the brain and body.

该系统在整个大脑和身体中都分布有受体。

Molecules native to the body called endocannabinoids also act on these receptors. 用詞

人体自身产生的被称为内源性大麻素的分子也会作用于这些受体。

We don't totally understand the cannabinoid system,

我们还没有完全了解大麻素系统，

but it has one feature that provides a big clue to its function. 表達脈絡

但它的一个特征为它的功能提供了重要线索。

Most neurotransmitters travel from one neuron to the next

大多数神经递质从一个神经元传递到下一个神经元，

through a synapse to propagate a message. 用詞

通过突触来传递信息。

But endocannabinoids travel in the opposite direction. 短語搭配

但内源性大麻素的传播方向正好相反。

When a message passes from the one neuron to the next,

当信息从一个神经元传递到下一个神经元时，

the receiving neuron releases endocannabinoids.

接收信息的神经元会释放内源性大麻素。

Those endocannabinoids travel backward to influence the sending neuron,

这些内源性大麻素反向传播以影响发送信息的神经元，

essentially giving it feedback from the receiving neuron. 語法

本质上是接收神经元向它提供反馈。

This leads scientists to believe that the endocannabinoid system 短語搭配

这让科学家们相信，内源性大麻素系统

serves primarily to modulate other kinds of signals, 用詞

主要作用是调节其他类型的信号，

amplifying some and diminishing others. 表達脈絡

放大一些信号并减弱另一些信号。

Feedback from endocannabinoids slows down rates of neural signaling.

内源性大麻素的反馈会减慢神经信号的传输速度。

That doesn't necessarily mean it slows down behavior or perception, though. 短語搭配

但这并不一定意味着它会减慢行为或感知的反应。

For example, slowing down a signal that inhibits smell

例如，减缓一种抑制嗅觉的信号，

could actually make smells more intense. 語法

实际上可能会让嗅觉更敏锐。

Marijuana contains two main active compounds, 用詞

大麻包含两种主要的活性化合物：

tetrahydrocannabinol, or THC, 文化背景

四氢大麻酚（THC），

and cannabidiol, or CBD.

和大麻二酚（CBD）。

THC is thought to be primarily responsible for marijuana's psychoactive effects 講解

人们认为THC主要负责大麻的精神活性作用，

on behavior, cognition, and perception.

影响行为、认知和感知。

While CBD is responsible for the non-psychoactive effects, 語法

而CBD则负责非精神活性作用，

like endocannabinoids, THC slows down signaling

就像内源性大麻素一样，THC会减慢信号传输，

by binding to cannabinoid receptors, 短語搭配

它的方式是与大麻素受体结合，

but it binds to receptors all over this sprawling, diffuse system at once, 用詞

但它会同时与这个庞大、分散系统中的各处受体结合，

whereas endocannabinoids are released in a specific place 語法

而内源性大麻素则是在特定的位置释放，

in response to a specific stimulus.

以响应特定的刺激。

This widespread activity,

这种广泛的活动，

coupled with the fact that the cannabinoid system indirectly affects many other systems, 語法

加上大麻素系统会间接影响许多其他系统的事实，

means that each person's particular brain chemistry,

意味着每个人独特的大脑化学成分、

genetics, and previous life experience

基因以及过往的生活经历，

largely determine how they experience the drug. 短語搭配

在很大程度上决定了他们对这种药物的体验。

That's true much more so with marijuana than with other drugs 語法

与那些通过一条或几条特定途径产生作用的其他药物相比，

that produce their effects through one or a few specific pathways.

大麻在这一点上表现得尤为突出。

So the harmful effects, if any, 語氣意圖

因此，有害影响（如果有的话），

vary considerably from person to person.

会因人而异地有很大差别。

And while we don't know exactly how marijuana produces specific harmful effects, 表達脈絡

虽然我们并不确切知道大麻是如何产生特定有害影响的，

there are clear risk factors that can increase people's likelihood of experiencing them.

但有一些明确的危险因素会增加人们经历这些影响的可能性。

The clearest risk factor is age. 用詞

最明显的危险因素是年龄。

In people younger than 25,

在25岁以下的人群中，

cannabinoid receptors are more concentrated in the white matter 語法

大麻素受体更集中在白质中，

than in people over 25.

比例高于25岁以上的人群。

The white matter is involved in communication, 短語搭配

白质参与沟通、

learning, memory, and emotions.

学习、记忆和情绪控制。

Frequent marijuana use can disrupt the development of white matter tracts 短語搭配

频繁使用大麻会破坏白质束的发育，

and also affect the brain's ability to grow new connections. 短語搭配

还会影响大脑建立新神经连接的能力。

This may damage long-term learning ability and problem solving.

这可能会损害长期的学习能力和解决问题的能力。

For now, it's unclear how severe this damage can be 語法

目前还不清楚这种损害会有多严重，

or whether it's reversible.

或者它是否可逆。

And even among young people,

即使在年轻人中，

the risk is higher the younger someone is, 語法

年纪越小风险也越高，

much higher for a 15-year-old than a 22-year-old, for instance.

比如15岁的人风险就比22岁的人高得多。

Marijuana can also cause hallucinations or paranoid delusions,

大麻还可能导致幻觉或偏执性妄想，

known as marijuana-induced psychosis. 用詞

这被称为大麻诱发的精神病。

These symptoms usually subside when a person stops using marijuana, 用詞

这些症状通常在人们停止使用大麻后就会消退，

but in rare cases, psychosis doesn't subside,

但在罕见的情况下，精神病并未消退，

instead unmasking a persistent psychotic disorder. 用詞

反而暴露了潜在的持续性精神障碍。

A family history of psychotic disorders, like schizophrenia,

有精神分裂症等精神障碍家族史，

is the clearest, though not the only risk factor for this effect. 語氣意圖

是导致这种影响最明显（虽然不是唯一）的危险因素。

Marijuana-induced psychosis is also more common among young adults,

大麻诱发的精神病在年轻人中也更常见，

though it's worth noting that psychotic disorders usually surface in this age range anyway. 講解

不过值得注意的是，精神障碍无论如何都通常会在这个年龄段显现。

What's unclear in these cases 語法

在这些案例中尚不清楚的是，

is whether the psychotic disorder would have appeared without marijuana use,

是如果不吸食大麻，这种精神障碍是否也会出现，

whether marijuana use triggers it early, 用詞

还是吸食大麻导致其提前发作，

is a catalyst for a tipping point that wouldn't have been crossed otherwise, 習語

或是它作为催化剂突破了原本不会被跨越的临界点，

or whether the reaction to marijuana is merely an indication of an underlying disorder. 用詞

又或者对大麻的反应仅仅是潜在疾病的一个迹象。

In all likelihood, marijuana's role varies from person to person. 短語搭配

十有八九，大麻所起的作用因人而异。

At any age, as with many other drugs,

不论年龄多大，就像许多其他药物一样，

the brain and body become less sensitive to marijuana after repeated uses, 用詞

多次使用后，大脑和身体对大麻的敏感度会降低，

meaning it takes more to achieve the same effects. 語法

意味着需要更大的剂量才能达到同样的效果。

Fortunately, unlike many other drugs,

幸运的是，与许多其他药物不同，

there's no risk of fatal overdose from marijuana, 用詞

吸食大麻没有致命过量的风险，

and even heavy use doesn't lead to debilitating or life-threatening withdrawal symptoms 用詞

即使大量吸食，在停止使用后，

if use stops.

也不会导致令人衰弱或危及生命的戒断症状。

There are more subtle forms of marijuana withdrawal, though, 用詞

不过大麻戒断也有更不易察觉的形式，

including sleep disturbances,

包括睡眠障碍、

irritability, and depressed mood,

易怒和情绪低落，

which pass within a few weeks of stopping use. 短語搭配

这些症状在停止使用后的几周内就会消失。

So, is marijuana bad for your brain?

那么，大麻对你的大脑有害吗？

It depends who you are. 表達脈絡

这取决于你是谁。

But while some risk factors are easy to identify, 表達脈絡

虽然有些危险因素很容易识别，

others aren't well understood,

但另一些我们了解得还不够透彻，

which means there's still some possibility of experiencing negative effects, 語法

这意味着仍然有可能遭受负面影响，

even if you don't have any of the known risk factors. 語法

即使你没有任何已知的危险因素。

The world's most widely used drug is caffeine.

世界上使用最广泛的药物是咖啡因。

Over 100,000 metric tons are consumed every year.

每年消耗量超过10万吨。

How exactly does it keep us awake?

它究竟是如何让我们保持清醒的？

Find out with this video.

通过这段视频来一探究竟吧。