AUG 20, 2019 8:44 AM PDT

What Causes Addiction?

WRITTEN BY: Annie Lennon

From nicotine to heroin, addiction is thought to be a reactive behavior to certain substances with addictive qualities. And so, convention has it that the best way to avoid addiction is to simply avoid them. But is this really the case? How else may addiction happen? 

It is difficult to pinpoint an isolated cause for addictive behaviors. In fact, it seems that they arise from a mosaic of different traits, including those from our genes and environmental factors. Although certain substances, such as nicotine, are known to be addictive, researchers have found that genetic traits may increase one’s likelihood of addiction to them. For example, a certain variant of the CHRNA5 gene can double one’s likelihood of developing a nicotine addiction, as it essentially softens nictotine’s negative effects, thus making it more pleasant to ingest than with other variants of the same gene (Fowler: 2014). 

Likewise, certain genes are also known to reduce one’s risk of developing an addiction. For example, a study of over 4,500 East Asian people found that those with a specific variant of the ALDH2 gene are nine times less likely to develop abusive drinking habits than those with other variants. This comes as this variant disables one’s ability to metabolise alcohol into acetate from the toxin, acetaldehyde. The buildup of this toxin in the body then causes nausea and general feelings of discomfort, thus discouraging the person from further drinking (Luczak: 2006). 

At this point, it is worthwhile seeing how environmental factors key in too. Between 1979 and 1992, a study found that the percentage of people who had this version of the ALDH2 gene and displayed abusive drinking habits increased from 2.5% to 13% (Ray: 2016). This is thought to have happened due to the introduction of a heavy drinking culture among Japanese businessmen, as well as stress from surmounting economic pressures as the economy began to weaken (Lennon: 2019). Thus, although genetic factors seem to influence one’s likelihood of developing addictive behaviors, their likelihood of manifesting seems to be closely interlinked with environmental triggers. 

Looking closer at environmental triggers, in the book “Chasing the Scream”, Johann Hari summises that addiction is caused by a lack of connection to one’s environment, as opposed to other factors. To make his point, he cites the “Rat Park” experiment. Conducted in the 1970’s, the experiment is famous for observing how, when left alone in cages in unhealthy living conditions with a bottle of plain water and a bottle of heroin-infused water, rats tended to prefer the water with heroin. Yet, when left in a cage with other rats and healthy living quarters, they preferred the plain water. From this experiment, and other examples, Hari says that addiction is therefore not just caused by chemical triggers, but how our environments make us susceptible to them. In this way, stressful environments are more likely to induce damaging behaviors, whereas more relaxed environments make them irrelevant (Hari: 2017). 

To conclude, addiction is caused by myriad factors beyond, although still including, addictive substances themselves. Thus, to understand the true causes of addiction, it is necessary to consider these factors taken together, as interlocking factors, rather than causes in isolation. After all, although an addictive behavior may be made more likely due to the presence of a certain gene, perhaps it was triggered by a certain environment. 



Fowler, CD: Pub Med

Luczak, SE: Pub Med 

Ray, Lara A.: US National Library of Medicine 

Lennon, Annie: Labroots 

Hari, Johann: Huffpost 

About the Author
Bachelor's (BA/BS/Other)
Annie Lennon is a writer whose work also appears in Medical News Today, Psych Central, Psychology Today, and other outlets.
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