What causes addiction, and why is it so hard to treat? - Judy Grisel

譯者: Lilian Chiu 審譯者: SF Huang

As of 2021, more than 36 million people worldwide

截至 2021 年，

估計全球有超過三千六百萬人有

were estimated to be experiencing substance abuse disorder.

物質濫用障礙。

This condition spans a spectrum of patterned drug use

這種病症包涵一系列會造成 個人生活問題的藥物使用模式。

that causes issues in a person’s life.

At the more severe end of the spectrum is substance addiction.

這些模式中比較嚴重的 就是物質成癮。

To understand why some people are more susceptible to addiction

若要了解為什麼有些人 比較容易成癮，

and why it can be so difficult to treat,

及成癮為什麼這麼難治療，

let’s take a look at how addictive drugs affect the body.

就要先看看成癮藥物會如何影響身體。

When someone repeatedly uses an addictive substance,

當有人重複使用成癮物質時，

their brain may adjust to account for its regular presence.

他們的大腦可能會做調整， 以應對這種物質的常規性存在。

This is called tolerance; it diminishes the drug’s effect

這就是耐受度；

它會減少藥物的作用，

and means more is required to produce the same experience.

意即，需要更多的量 才能產生相同的體驗。

Alcohol, for instance, increases the transmission of chemical messengers

以酒精為例，它會增加 化學傳訊者的傳遞，

like endorphin and GABA,

如腦內啡和 γ-氨基丁酸，

which promote sensations of pleasure and calmness.

促進愉悅和平靜的感覺。

When someone uses alcohol frequently, their brain will adapt to its presence.

經常使用酒精的人

大腦會適應酒精的存在。

So when they don’t use it, their brain receives fewer signals

因此，當他們不使用時，

大腦就較少接收到來自那些促成 愉悅及平靜的神經傳遞質的訊號。

from those pleasure- and calm-inducing neurotransmitters,

which impacts their energy and mood.

他們的能量和心情因此會受到影響。

In addition to the unique effects each addictive substance has,

每種成癮物質皆有其 獨特的效果，除此之外，

all of them alter the release of dopamine

它們全都會改變 伏隔核這個大腦區域中

in a brain region called the nucleus accumbens.

多巴胺的釋放。

This area is part of the brain’s reward pathway,

這個區域是大腦獎勵途徑的一部分，

which is sensitive to experiences that give us pleasure

它對於帶給我們愉悅的經歷很敏感，

and drives us to repeatedly seek them out.

並會驅使我們反覆去追求這些經歷。

The reward pathway is essential to our well-being—

獎勵途徑對我們的健康至關重要——

but addictive substances also exploit it.

但成癮物質也會利用它。

When someone is repeatedly using a substance

當人重複使用某種物質，

and their body has adapted to its presence,

且他們的身體已適應了 該物質的存在時，

they may develop dependence

他們可能會發展出依賴性，

where the drug is necessary for them to function comfortably.

也就是說，他們需要 該藥物才能舒適地過生活。

Meanwhile, repeated use can decrease the influence of the brain’s cortex,

同時，重複使用可能會 減少大腦皮質的影響，

which is responsible for driving deliberate decision-making

皮質負責推動有意圖的決策，

and limiting impulsive behaviors.

並限制衝動行為。

And it can increase the influence of the brain’s subcortex,

此外，下皮層的影響會增加，

which is crucial in habit-learning and impulsivity.

下皮質對於習慣的習得 和衝動性至關重要。

Together, these changes can make someone feel a lack of control

這些變化一起發生時， 會讓人感到無法控制

over how they’re using a substance.

他們如何使用物質。

This can mean suffering in other facets of their life

這可能意味著生活的 其他方面也因而受苦，

and taking risks to continue using it.

以及冒險繼續使用它。

If the substance leaves their system, their body's equilibrium is disrupted,

如果該物質離開他們的系統， 他們的身體平衡會被破壞，

so they may experience cravings that motivate thoughts and behaviors

因此他們可能會產生渴 望，

引發想要去尋求和使用 該藥物的想法和行為。

of seeking and using the drug.

And if they continue without the substance,

如果他們持續不使用該物質，

they may experience withdrawal.

可能會出現戒斷。

Opioids, for example, relieve pain and induce sedation.

比如鴉片類藥物可以 緩解疼痛並帶來鎮靜。

Withdrawal from them causes heightened pain, anxiety, and insomnia.

戒斷該藥物會造成更嚴重的疼痛、

焦慮及失眠。

The faster a drug reaches the brain and stimulates the reward pathway,

藥物越快到達大腦並刺激獎勵途徑，

the more addictive it is.

就越容易造成成癮。

For example, heroin and morphine have similar effects,

例如，海洛因和嗎啡 具有類似的作用，

but heroin’s chemical structure enhances its ability

但海洛因的化學結構

讓它更容易穿透血腦屏障，

to penetrate the blood-brain barrier and bind to specific receptors.

與特定的受體結合。

This makes it faster acting and more addictive than morphine.

這就讓它比嗎啡的作用 更迅速且更容易成癮。

Meanwhile, compared to nicotine patches and gum,

同時，與尼古丁貼片和口香糖相比，

regular and electronic cigarettes are more addictive

普通香菸和電子菸更容易成癮，

because smoking and vaping deliver nicotine to the brain fastest.

因為抽一般香菸和電子菸

是將尼古丁送至大腦的最快方式。

Depending on their chemical structure and mode of delivery,

取決於其化學結構和給藥方式，

drugs vary in how addictive they are—

不同藥物的成癮程度也不同——

but people also vary in how susceptible they are to substance use disorder.

但不同的人會受到物質使用 障礙的影響程度也不同。

Scientists think this is due to a mix of life experiences

科學家認為這是生活經驗 和遺傳特徵的綜合結果，

and genetically inherited traits,

though neither predetermines addiction.

不過兩者都不代表就一定會成癮。

Trauma and mental health conditions appear to make people more susceptible.

創傷和心理健康狀況顯然 也會讓人更容易受到影響。

And, overall, using addictive substances before 18

總的來說，在十八歲 之前使用成癮物質

is considered a strong risk factor.

被認為是很強的風險因子。

This is in part because the reward pathways of younger brains

有部分原因是因為 較年輕者的大腦獎勵途徑

are especially sensitive.

會特別敏感。

Many of the genetic factors at play remain unknown,

許多相關的遺傳因子仍然未知，

but some genes do seem to track with certain substance use disorders.

但有些基因確實似乎 與某些物質使用障礙有關。

For example, specific genes increase the risk for nicotine addiction

比如，特定的基因 會增加尼古丁成癮的風險，

by making certain receptors more sensitive to nicotine

因為這些基因會讓受體 對尼古丁更敏感，

and withdrawal from it more difficult.

戒斷也就更困難。

At the same time,

同時，

some genes actually make people more resistant to substance use disorders,

實際上還有些基因能讓人 更能夠抵抗物質使用障礙，

such as genes that slow the breakdown of alcohol,

比如減緩酒精分解的基因，

leading to unpleasant side effects that make people less interested in drinking.

會導致令人不愉快的副作用， 從而減少人們對飲酒的興趣。

In fact, one drug that treats alcohol use disorder

事實上，用來治療 酒精飲用障礙的一種藥物

operates with this very mechanism.

就是仰賴這種機制。

Detoxing from a substance the body has become dependent on

當身體已經變得很依賴某物質時， 要將該物質清除掉就可能極困難。

can be extremely difficult.

And in some cases, abruptly quitting can also be physically risky,

在某些情況下，突然戒除 也可能會造成身體上的風險，

so it isn’t always advised.

因此不見得都會建議這麼做。

Beyond detoxing, quitting is often a long-term process.

除了排毒之外，戒除通 常是一個漫長的過程。

It’s aided by treatment plans that prioritize

要有治療計畫協助，這些計畫 會優先處理潛在的病症；

addressing underlying conditions;

developing new associations with experiences

針對先前和藥物使用相連結的 經歷，發展新的關聯性；

previously linked with drug use;

and creating safe, supportive environments.

並創建安全、提供支持的環境。

Ultimately, both addiction and recovery are the results of a brain

到頭來，成癮和康復

都是在經歷中擁有驚人調適能力的 大腦所產生的結果。

with an incredible ability to adapt from experience.