The Role Genetics Plays in Drug Addiction

Substance use disorder, or drug addiction, is a complicated brain disorder and behavioral condition. There is no single cause, but ongoing research has found that a number of genes and related factors play a significant role in addiction. A complex interaction between genetics and environment makes some people more susceptible to addiction than others. As researchers get a better handle on the causes of addiction, genetic studies should lead to better, more targeted recovery plans.

Research into addiction and genes shows that genetics account for anywhere between 40% and 60% of the risk of becoming addicted to a substance.

Drug use is a choice, but it’s not a simple one. The mechanism of using drugs and becoming addicted is also complicated.

Genes play a big role in who gets addicted, the risk of developing an addiction, and drug-seeking behaviors in general. It’s important for anyone to understand this link, but especially for people with addiction in their families. Know the special risks you face so you can make smarter, better choices.

If You Have Addiction in Your Family

While modern science allows research to dig down to the molecular level of addiction, experts have long connected it to family history. You don’t need a lot of genetic technology to see that addiction often runs in families.

This doesn’t mean that you’re destined to become addicted to drugs if your parents or siblings are. It simply means that you have an increased risk, which may be tied to genetics. Another important factor is environment. If you and your sibling develop a drug use disorder, it may be related to genetics but also the fact that you grew up in the same household with risk factors, like abuse or trauma.

Observations indicate that family history plays a role in addiction, but researchers have also proven it. Studies show that addictions range from moderately to highly heritable. Your risk of developing an addiction increases with the degree of your genetic relationship to an addict. In other words, your risk is higher if your parents struggle with addiction than if an aunt or cousin does.

Are There Genes for Addiction?

That drug addiction is heritable implies that there are genes for it. Your parents may pass on genes to you that make you more likely to develop an addiction. Gene sequencing has led to incredible revelations about diseases, some of which are caused by a single mutation, or change in a gene.

Unfortunately, addiction is not that simple. There is no single gene or group of genes that cause this complicated disease. Researchers look for all kinds of genetic differences in people with drug addiction to determine underlying causes. These differences increase addiction risk. These are some examples:

  • A gene called Mpdz may code for extra protein that leads to less severe withdrawal from certain drugs. If your withdrawal is milder, you are less likely to keep using to get relief, and therefore less likely to become addicted.
  • Per1 and Per2 genes in animal studies can have variations in their sequences that trigger mice to consume more alcohol when stressed. If a person has this variation, they may be more likely to drink when under stress and to become dependent.
  • Fruit flies missing a gene called moody are more sensitive to cocaine. Drug sensitivity increases the risk for addiction.
  • Specific variations in the OPRM1 gene, which codes for a receptor for opioids, are more likely to occur in people with opioid addictions.
  • DRD2 is a gene that in a certain form occurs more often in people addicted to cocaine, opioids, and alcohol. Researchers believe it’s related to the brain’s reward pathway.

These are just a few of the many genetic variations that contribute to addiction risk. None of these causes addiction to drugs, but the more you have, the greater your risk.

Genes Plus Environment Equals Epigenetics

Epigenetics is an area of research that looks at the regulation and expression of genes. Environmental factors and lifestyle choices can actually change the action of your genes and the proteins produced based on those genes. These things don’t change the sequence of your genes, only how they are expressed.

In terms of addiction, studies find that some epigenetic changes impact your risk of using or becoming addicted to drugs. Stress, for instance, triggers the release of hormones that can change gene expression in brain cells. These changes can make you more susceptible to using drugs or to relapsing in recovery.

Ordinary stress is not a huge risk factor, but researchers have found that severe stress, or childhood trauma, significantly impacts addiction risk because of epigenetic changes. In one study, children who lost their parents had a parent diagnosed with cancer, or who witnessed domestic abuse, were two times more likely to develop a drug addiction.

Drugs themselves can also produce epigenetic changes. Cocaine use increases the production of certain proteins as coded by specific genes. These proteins, related to substance abuse, have been seen to correlate with increased drug use.

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How Does Environment Affect Addiction Risk?

The environment in which you grow up and live as an adult can impact your risk for drug addiction through these epigenetic changes. Together with specific genes and family history, the contribution of genetics is significant.

Even without considering epigenetics, environment matters. For example, a study of people in China, Japan, and other Asian countries found that many people in this population have a gene that protects against alcohol addiction. It interferes with the metabolism of alcohol, making drinking even a small amount unpleasant.

In spite of this protective gene common in the population, researchers found that alcohol abuse rose significantly in Japan between 1979 and 1992. This coincided with a period of time in which a culture of heavy drinking among businessmen developed. Many men found themselves in an environment that promoted and rewarded drinking, which changed their behaviors.

Developing Better Treatments, Thanks to Genetics

Knowing the role of genes in addiction is so important for prevention. If you know you have risk factors based on genetics and your family history and background, you can make a better choice about experimenting with drugs.

The other benefit of a greater understanding of the genetic foundation of drug addiction is that it can lead to more effective recovery plans. Each individual’s genes determine how they respond to types of professional help, how they metabolize drugs, what their withdrawal is like, and how they respond to medications.

Some researchers are working on precision or individualized care plans, medications, and other therapies designed to work specifically for an individual. Some people, for instance, may react better to naloxone treatment for opioid addiction. Understanding a person’s genetics is crucial for giving better care.

Drug addiction will never be as simple as turning a gene on or off. It is a complicated illness that many people struggle with, no matter how much they want to stop. As genetic research continues, experts have hope that it will become easier to prevent and treat drug addiction in those most vulnerable and at risk.