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Genetics And Their Role In Addiction

A fun fact about me is that I like to think about the nature vs. nurture aspect of almost every topic I encounter. Addiction was no different. It feels natural to think it’s something heavily influenced by outside factors more than anything internal but does it have to be one or the other all the time?

Addiction is defined as a neuropsychological disorder that leads to intense urges to engage in activities that result in short-term sensory satisfaction but long-term consequences. Over time our brain becomes dependent on our chosen activity or substance and cannot function without it. Today we will discuss substance abuse in particular.


The fact of the matter is addiction is a disease. Like many other diseases, this one worms its way into our DNA too. Barr et al. (2022) discussed how the heritability factor varies according to the drug. The chances of being more likely to have an alcohol-using disorder are 50 percent which goes up to 70 percent for other drugs. All because of differences in our DNA. The average DNA sequence of two people is about 99.9 percent the same! But the 0.01 percent is what contributes to the visible and invisible differences in human beings, including addiction.

Family studies that include identical twins, fraternal twins, adoptees, and siblings suggest that as much as half of a person's risk of becoming addicted to nicotine, alcohol, or other drugs depends on his or her genetic makeup. (Genetics and Epigenetics of Addiction, 2019, p1)

Scientists study the genetic makeup of different drug addicts to find ways of prevention and therapy. A study done on cannabis users suggests that an underexpression of the gene CHRNA2 in the cerebellum is directly associated with cannabis use disorder along with various other genes that play their respective roles. (Agrawal and Lynskey, 2009, p6). Various studies done in the past years have suggested strong evidence of genetic influence on cannabis addiction.

As mentioned above, genetic factors contribute about 50 percent to alcohol addiction if you have a family history of alcoholism although the gene can skip a generation. Alcoholism and genetics is a topic that is currently under heavy research but certain genes can lower the risk of alcoholism! Some people of Asian descent have a gene that can alter their alcohol metabolism, causing them to have symptoms like flushing or erratic heartbeat when they drink. This leads to them avoiding alcohol thus decreasing their risk of developing alcohol abuse disorder.

Physicians used to prescribe opioids for chronic issues with poor evidence of strong pain leading to an uptick in addiction from 1999 upwards. Madras (2017) stated, “From 1999 onwards, overdose deaths due to prescription opioids rose incrementally and consistently outpaced annual heroin death rate.” Tsuang et al (1998) indicated that up to 54 percent of liability for opioid addiction was because of genetic variances and up to 38 percent was explained by genetic variance specific to opioid abuse. Berrettini (2017) found that people of European descent with a family or personal history of substance abuse are at a higher risk of addiction.

The question should never be whether it’s nature or nurture but rather nature and nurture. Genetics is never the only factor at play. While parents with a drug abuse history may pass on the addiction risk they would also create an unsafe environment for the child that may push them to abuse substances. Our environment plays just as much of a role. It’s important to study and recognize the demographics at risk due to genetic factors so prevention methods can take place.


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