How does alcohol cause blackouts? - Shannon Odell

Translator: Fong Wang Andy Yip Reviewer: Thomas Tam

In 1969, Dr. Donald Goodwin gathered a group of study participants

喺1969年，當Donald Goodwin博士 搵咗一班研究對象

and asked them each to recall the object he'd shown them two minutes prior.

問佢哋記唔記得 兩分鐘前畀佢哋睇嘅嘢

The twist?

問題係

All the participants were very intoxicated.

所有參加者都非常咁醉

Despite this, most could pay attention to the task

即使係咁，大部份人都能夠專注

and correctly name the toy they had just seen.

並講得啱頭先睇到咩嘢

Yet, when Donald asked them to recall that object a mere 30 minutes later,

但當古德曼博士 要佢哋回憶30分鐘前睇到嘅嘢

half the participants drew a blank,

有一半人都記唔返

having “blacked out” the earlier moment entirely.

腦海「斷片」 記唔返早前嘅事

This study illustrates the strange and somewhat selective effects

呢個實驗顯示咗酒精

選擇性對大腦造成奇怪嘅影響

alcohol has on the brain.

Many intoxicated people can perform complex tasks

好多飲醉嘅人 其實都做得到複雜嘅嘢

like holding a detailed conversation or navigating a walk home.

例如同人深入對話 或者搵路返屋企

Yet for those experiencing what is known as a blackout,

但係當醉嘅人 遇到所謂「斷片」

the memory of these events is quickly forgotten.

就會忘記晒期間所做嘅嘢

So how does alcohol cause these memory lapses?

究竟酒精係點 導致喪失咗部分記憶？

First, let's identify the culprit.

等我地先認清元兇

While a single drink often contains hundreds of different chemical compounds,

一杯酒可以有過百個化合物

ethanol is responsible for alcohol's effects on the brain.

但其實乙醇先至係影響大腦嘅成分

Ethanol is lightweight and lipophilic,

乙醇係輕質而且親脂性

meaning its structure easily dissolves into fats,

令佢非常容易溶於脂肪

like those in the membranes of the outer blood-brain barrier.

正正係外血腦屏障膜嘅成份

Once inside the brain, ethanol’s unique structure

進入腦部後 乙醇獨特嘅構造

allows it to bind to, interact, and affect many different neuronal receptors,

令佢哋能夠同好多 唔同嘅神經元受體結合

impairing pathways that allow you to make careful decisions, control your impulses,

相互作用和影響

影響人謹慎決策，自我控制 同埋管理運動技能嘅能力。

and even manage your motor skills.

And the networks that control memory seem to be especially sensitive

而控制記憶嘅神經網絡

似乎特別容易受到酒精影響

to alcohol’s effects.

Typically, information about your surroundings is taken in

一般而言，感官會收集 四周嘅資訊再傳送畀大腦

by your sensory organs and sent to the brain.

Neurons transfer this information to one another

神經細胞會釋放 「神經傳導物質」

via chemical messengers called neurotransmitters,

而佢哋會就會將訊號

which are released by one neuron and received by receptors at another.

送畀下個神經細胞嘅接收器

When a neurotransmitter binds to a receptor,

當神經傳導物質同接收器連結

it unlocks an internal channel, allowing small ions to flow into the cell.

神經細胞入面嘅通道就會打開 等細小嘅離子流入

If enough ions enter the cell, the neuron fires,

如果離子進入細胞夠多 神經細胞就會放電

sending the signal forward.

將訊息送出去

Through this process, different regions of the brain

大腦各部分就係透過呢個方法

can communicate with one another in milliseconds,

以微秒嘅速度互相溝通

creating our moment-to-moment understanding of the world.

我哋就係咁樣 時時刻刻理解呢個世界

But ethanol interacts with receptors,

但係乙醇會阻礙接收器

making it harder for neurons to communicate.

令神經細胞更難互相溝通

While compromised, the brain is still able to transfer information,

即使能力下降 大腦仍然能夠傳遞訊息

which is why many intoxicated people seem somewhat capable

所以飲醉嘅人

都仍然能夠完成簡單任務

of performing basic tasks.

In other words, brain function is highly impaired,

換言之，大腦功能大幅減弱

but not completely broken.

但唔代表完全喪失

But memory storage is a different story.

但記憶就完全唔同講法

The transfer of moment-to-moment understanding

要將每刻嘅體驗儲存為記憶

to something we can remember is thought to depend on a process

就取決於另一種過程

called long-term potentiation, or LTP.

就係「長期增強作用」 簡稱LTP

LTP happens throughout the brain,

LTP喺成個大腦都會發生

but is especially important in learning and memory regions,

但喺學習同記憶嘅部份 就尤其重要

like the neocortex and the hippocampus.

例如新皮質同埋海馬體

During LTP,

LTP過程中

the firing of a neuron triggers physical changes to its structure.

神經細胞嘅放電 會令通道物理結構改變

For example, more receptors may be moved to the cell's surface,

例如，更多受體會移動到細胞表面

making the neuron more sensitive to future signaling from its neighbors.

令神經細胞對未來信息更加敏感

These physical changes increase the likelihood that a cell

呢種物理改變會令細胞

will fire again at that connection,

喺呢個連接處再次放電

strengthening the wiring between neurons.

增強神經細胞之間連結

And through this stronger connection,

普遍認為當細胞連結增強

it's thought that a stable memory is formed.

就會形成穩定嘅記憶

Yet studies suggest that ethanol has a unique ability to disrupt LTP,

但研究發現乙醇 有擾亂LTP嘅能力

blocking the physical changes needed for memory formation.

阻礙結構嘅改變 令記憶無法形成

So, while moment-to-moment information is encoded and understood,

雖然大腦仲可以處理 時時刻刻嘅資訊

the storage of that information is blunted,

儲存資訊嘅能力就減弱咗

resulting in a blackout.

導致腦海斷片

Of course, not all levels of drinking result in blackouts.

當然，飲酒唔一定會斷片

They happen when the concentration of alcohol in the blood, or BAC,

當血液嘅酒精含量，又稱BAC 超過一定濃度

exceeds a certain level, approximately 0.16.

大約百分之0.16左右 先致會發生斷片

But there’s no magic number.

但呢個數字並非絕對

At slightly lower BACs, brownouts, or the spotty memory of events, can occur,

BAC濃度較低嗰陣 記憶可能會變得模糊

as some neurons continue to function properly while others fail.

因為只有部分細胞正常運作

And drinking too much can cause a person to pass out altogether.

再者，飲太多可能會直接導致昏迷

Other factors like dehydration level, genetic differences, medications,

其他因素 包括脫水程度、遺傳差異、藥物

and even how much you’ve eaten can affect the likelihood of a blackout.

甚至之前食咗幾多嘢 都可以改變斷片發生嘅機率

And teenagers appear to be especially vulnerable

而青少年因為大腦正處於發展期

due to the substantial changes in brain development during those years.

似乎特別容易受到傷害

Alcohol’s short-term effects usually don’t last longer

酒精嘅短期影響 只會持續一日左右

than the time it takes for their body to metabolize it, or about a day.

當身體分解晒酒精，就會冇事

But repeatedly over-drinking can damage neurons and permanently impair memory.

但長期酗酒可能會傷害神經細胞 永久傷害記憶

It can also harm other organs like the liver,

飲酒亦都有可能傷害器官

例如需要分解大量酒精嘅肝臟

which works overtime breaking down alcohol.

After all, experiencing a blackout or witnessing others

無論係自己斷片

抑或係睇到其他人斷片嘅狼狽樣

in this compromised state

can be a lot for your mind and body to process.

都可能會對身心做成負擔