Why do some people become addicted while others do not? Substance use disorders (SUDs) often run in families. Researchers have studied families with high rates of addiction and found that about half of a person’s risk of developing a SUD depends on his or her genetic makeup. Pinning down the biological basis for this risk is an important avenue of research that will help scientists develop better, more personalized prevention and treatment strategies.
Many Genes Influence Substance Use Disorders
Genes are the basic units of our DNA that direct the development and functioning of every cell in our bodies. Research has shown that, on average, the DNA sequences of any two people are 99.9 percent the same. But that 0.1 percent variation is important. These differences contribute to visible differences between people, such as height and hair color, as well as invisible traits, such as increased risk for certain health conditions like heart attack, stroke, diabetes, and addiction.
Some diseases, such as sickle cell anemia or cystic fibrosis, are caused by an error or “mutation” in a single gene. However, most diseases, including SUDs, are much more complex. Variations in many different genes contribute to a person’s overall level of risk or protection from a SUD. In addition, environmental factors like quality of sleep, diet, or stress, can directly influence how genes act.
Genes that Influence Substance Use Disorder
So far, most of the genes that researchers have found to influence the risk for a SUD fall into a few categories:
Genes that influence how we respond to a substance - For example, some people have a gene variation that makes them feel dizzy and sick when they smoke cigarettes. People with this variation are less likely to become smokers.
Genes that influence how we metabolize a drug - For example, some people carry a gene that makes them metabolize opioids faster. Studies suggest that they may be more susceptible to opioid use disorder.
Genes that influence how we respond to treatment - For example, one study found that people with a gene that causes them to metabolize nicotine slowly do better when treated with the nicotine patch, while those who metabolize nicotine at a normal rate do better with the medication varenicline (Chantix®).
Genes that influence personality traits - For example, people who are more impulsive or sensitive to rewards are more likely to try substances and to develop SUDs.
Substance Use Disorders are not Inevitable
People who have genetic risk factors for substance use disorders are more likely to try drugs and alcohol and to develop SUDs but these outcomes are not guaranteed. Prevention programs targeting high-risk youth can reduce or delay the initiation of substance use and people with high genetic risk can be successfully treated if they do develop a SUD.
If you or someone you love has a family history of addiction, there are many strategies that can help reduce one’s risk, including:
Delaying initiation of substance use: The adolescent brain does not finish developing until the early to mid-20s, which is why teens are much more susceptible to developing SUDs than adults. Delaying the initiation of substance use until the brain has fully developed substantially reduces the risk for a future SUD.
Training in skills that address environmental risk factors, such as
Managing and coping with stress
Communicating needs and feelings
Refusing substances that are offered
Supporting protective factors, such as
Increasing parental involvement
Fostering positive passions (e.g. sports, music, science, etc.)
Knowing that you or your loved one is at increased risk for a SUD can help you take steps to reduce these risks and stop the cycle of addiction that is common in so many families.
How Understanding Genetics Can Improve Treatment and Recovery
Understanding how our genes influence SUDs can pave the way for precision medicine - where medical care is tailored to a person’s individual genetic risks. Precision medicine for a SUD could include targeting prevention strategies to people who are at high genetic risk for the disorder; regular SUD screening for those at high-risk; and tailoring treatment plans based on a patient’s specific genetic makeup - including identifying medications and dosages that work best for patients with specific gene variants.
Understanding a patient’s genetic risk for opioid use disorder can also help doctors minimize the risk for opioid misuse and addiction when treating a patient for pain. Such information could help doctors to be more cautious when prescribing an opioid for pain relief prescription, adjust the dose or duration of treatment, and screen more often for signs of misuse among high-risk patients who have been prescribed opioids.