Research shows that genetic factors play a strong role in the development of substance use disorders. A long-term, large-scale study published in the Nature Neuroscience journal Molecular Psychology found that people with the highest genetic predisposition to addiction had four times more risk of substance abuse issues than those with the lowest genetic risk.
However, scientists are still trying to understand how your genes and family history interact with environmental risk factors for alcohol and drug addiction. This guide provides an overview of how genetic makeup influences a person’s risk of substance misuse and addiction.
The Role of Genetic Factors in Alcohol and Drug Addiction
Even when someone’s genetic code includes risk factors for addiction, they won’t necessarily develop substance use disorder. According to the American Psychological Association, genetic information makes up about half of your addiction risk. Researchers from Rutgers University estimate that 50% of the risk of alcohol use disorder is genetic, increasing to 70% for other types of drug addiction.
In addition, your genetic risk may include complex interactions between many different genes involved in addiction, which makes it difficult to determine the exact level of genetic predisposition to alcohol and drug abuse. Most health care providers agree that a combination of nature and nurture affects each person’s risk of getting addicted to certain drugs.
Hereditary risk factors aren’t necessarily limited to a single gene or even multiple genes. As reported by the Cleveland Clinic, inherited dopamine levels could influence the likelihood of addiction. People with higher levels of dopamine, which affects the brain’s reward system, tend to be predisposed to risky behaviors such as substance use.
The Rutgers researchers reported that most genes that influence addiction are shared across many different substances. In other words, some of the same genes can potentially increase someone’s risk of both cannabis use disorder and opioid dependence. Other genes specifically influence one type of addiction, such as alcoholism.
Understanding the Difference Between Genetics and Heredity
When reviewing the research about addiction genes, it’s important to understand the difference between heredity and genetics. These terms are often misused to mean the same thing. Heredity describes the DNA sequences through which traits and characteristics pass down through families. Genetics is the scientific study of heredity, which primarily focuses on genes. These DNA units are inherited from our parents to make up our unique physiology. In the human genome, we share about half of our genes with our children, siblings and parents (first-degree relatives).
Risk Factors for Substance Use Disorders
Risk factors for developing alcohol and drug addiction cover two main categories. Environmental factors may include:
- Negative peer influences and related social factors
- Unstable family life
- Lack of healthy, safe activities after school
- Early exposure to trauma or stress, including adverse events such as divorce or death of a parent
- Health disparities, such as a higher environmental risk of certain diseases
- Early age at first use of drugs or alcohol
- Factors such as poverty that make it difficult or impossible to seek treatment for addiction and co-occurring mental health issues
- Living in a disadvantaged community without access to basic necessities, such as safety, fresh foods and clean air and water
Hereditary risk factors include genetic risk as well as:
- Parents and other family members who abuse substances
- Exposure to drug abuse and addiction at a young age
- Lack of care, involvement with and support by family members
- Personal or family history of mental health issues, including but not limited to depression, anxiety, bipolar disorder or post-traumatic stress disorder
How Specific Genes Influence Addiction
Although the study of genetics and addiction is an emerging science, research suggests that genes matter when it comes to who may develop substance use disorder. People may eventually be able to undergo genetic testing to determine whether they have a higher likelihood of genetically determined addiction.
Heritability and Substance Abuse
A 2021 review published in the journal Psychological Medication found that substance use disorders have strong patterns of heritability, which means inheritance plays a significant role. The researchers report that hereditary factors are strongest for nicotine and opioid addiction.
Dopamine and Addiction
A study published in the scientific journal PNAS looked at the association between dopamine and substance abuse. Researchers identified an RNA virus (human endogenous retrovirus-K HML-2 or HK2) that infects a gene in the human body that regulates dopamine activity.
Slow Alcohol Metabolism
The American Psychological Association published a meta-analysis of studies reviewing the link between slow alcohol metabolism and alcohol use disorder. Researchers looked at genetic test results from 4,500 Asian study participants. They identified a protective gene factor called the ALDH2 variant. People who don’t have this variant are about nine times more susceptible to alcohol use disorder than those who do have ALDH2.
Cannabis Use Disorder
Addiction to THC, the psychoactive ingredient in cannabis, likely has a genetic component. Researchers from Washington State University in St. Louis wanted to understand why only about 20% of people who use marijuana become dependent. Their large-scale study of nearly 400,000 cannabis users found two possible genetic factors. They identified the CHRNA2 gene, supporting earlier findings that implicated this gene in cannabis and nicotine abuse. They also newly associated a DNA region on chromosome 7 with marijuana addiction. This genetic area is also connected with risky actions and delays in language development.
In addition, the researchers reviewed the Adolescent Brain Cognitive Development Study. Their analysis associated a higher risk for cannabis misuse with a lower volume of white matter in the brain. This suggests that addiction has a physiological component.
Research on Environmental Factors in Addiction
Environmental research supports a variety of contributing factors for drug and alcohol abuse.
A 2016 study published in the Journal of Child & Adolescent Substance Abuse linked the availability of drugs and alcohol at home with higher rates of adolescent and young adult drug abuse. Substance abuse among family members in the household is linked with first substance use at an early age.
The National Institute on Drug Abuse emphasizes the importance of epigenetics when investigating how genetic makeup influences addiction. Epigeneticists study the functional and structural changes in the DNA sequence that can result from environmental factors. For example, exposure to traumatic events increases the level of stress hormones in the body, which may actually change the DNA to create a predisposition to addiction. The National Institute on Drug Abuse reports that using cocaine can alter the genes to increase the production of hormones associated with addiction.
Studies show that chronic stress can produce epigenetic changes that may give insight into the question, “Is addiction hereditary?” Harvard Health explains that ongoing stress triggers the brain to release glucocorticoids. These steroid hormones modulate the expression of many genes in the nervous system, including the reward system. Thus, chronic stress may disrupt the way this system works, which can lead to mental health concerns, including addiction.
The epigenetics field also derives disease insights from expansive data science sets. Computers can process incredible volumes of information to look for genetic structures and gene expression related to an increased risk of drug addiction. In a study published in Computational Biology, researchers used this technique to identify more than 1,500 human genes associated with addiction. They documented their results in a database called KARG, which features a web interface where other researchers can analyze and compare their own findings to expand institutional knowledge about addiction and the human genome.
As epigeneticists explore the question, “Is addiction hereditary?”, most theorize that substance abuse and addiction arise from a combination of brain changes and genetic and environmental factors. Ongoing use of alcohol or drugs affects gene expression in the nervous system, which triggers changes in the reward circuit. Over time, the pleasure you experience each time you abuse your substance of choice reinforces the damaged clinical pharmacology caused by addiction. Most scientists and doctors now believe that addiction is a brain disease with multiple contributing causes.
Reducing the Genetic Predisposition for Addiction
If you’re aware that you have genetic risk factors for substance abuse, such as family members who’ve struggled with addiction, you can take action to lower your likelihood of developing a problem with drugs or alcohol. The Cleveland Clinic recommends discussing your family’s history of substance use disorder with your health care providers. You can also talk about your concerns with a therapist, who can help you develop coping skills outside of substance abuse. You may also want to limit or completely avoid the use of drugs, alcohol and tobacco to prevent dependence from developing.
Behavioral therapies, medication, support groups and other evidence-based therapies can help if you or a loved one struggles with substance abuse. Call Anchor Addiction and Wellness Center today at (740) 779-6612 to learn more about the programs at our state-of-the-art treatment center.