The question of what causes addiction and how to cure it has lead to a persistent and troubling question: is addiction genetic? Answering this question impacts how we treat addiction for medical reasons, but it is also laden with cultural and emotional baggage—the language of guilt and personal responsibility. Here is the answer to the question, as far as it can be answered.
Why do some, but not all, people who try drugs become addicted?
Vulnerability to addiction varies from person to person, just like vulnerability to cancer or any other disease. No one factor controls whether a person will become an addict. Overall, the balance between risk factors and protective factors determine your risk; people with more risk factors and fewer protective factors are most likely to experience addiction. Both risk and protective factors can be biological and environmental—and obviously genes are a biological factor that may either be protective or place you at greater risk for addiction.
According to the National Institutes of Health (NIH), other risk factors include lack of parental supervision, aggressive behavior in childhood, experimentation with drugs, poor social skills, poverty, and availability of drugs outside the home (especially at school). NIH cites positive relationships, parental support and monitoring, anti-drug policies at school, academic competence, and community pride as protective factors. Obviously, these are mostly environmental.
There are biological factors that increase your risk of addiction. Of course genes are the primary example of this; experts believe that genetic factors account for around 40 to 60 percent of one’s vulnerability. That 40 to 60 percent includes the ways environmental factors impact how your genes function and are expressed—this area is called epigenetics, and it has to do not only with understanding how diseases work, but on the burgeoning field of personalized medicine.
Age, mental conditions, medical conditions, and developmental stage are also factors. For example, people with many kinds of mental illness and adolescents are at increased risk of drug abuse and addiction compared to others. Early use is another factor that combines environment and biology, since it affects the brain’s development and makes addiction more likely. Finally, how the drugs are administered is a factor in how likely a user is to be addicted; users who experience intense, instant highs such as those achieved after injecting and smoking are more likely to become addicted.
Genes and addiction: a nuanced area
So, we already know that most studies reveal that 40 to 60 percent of the addiction risk is genetically linked. Like other chronic diseases, there is a strong trend of addiction running in families. However, it’s important to realize what it means when experts talk about “addiction genes.” Genes that may be linked to addiction do not mandate or control addiction; rather, they cause biological differences that render people more vulnerable to addiction or related states such as severe symptoms of withdrawal.
Multiple genes which play roles in addiction have been identified already. Scientists have often relief upon animal models, especially mice, to identify these genes. Mice are usually the animals these experts use because they share a similar reward pathway in the brain—and many of the underlying genes for that pathway—with humans. Once researchers identify a gene that is linked to addiction in a non-human species, they next work to find similar DNA sequences in humans.
Thus far, here are a few of the genes scientists believe play a role in addiction:
- People addicted to cocaine or alcohol are more likely to have the A1 allele of the dopamine receptor gene DRD2.
- Withdrawal symptoms from hypnotics and sedatives like barbiturates are less severe in mice with increased expression of the Mpdz gene; for this reason, scientists believe more expression of this gene may make it easier to become addicted.
- Mice without the Htr1b gene, a serotonin receptor, are more attracted to alcohol and cocaine.
- Mice with low levels of neuropeptide Y and who have a defective Per2 gene due to mutation drink more alcohol.
- Mice with the Creb gene are more likely to develop an addiction to morphine.
Scientists research on genes and addiction so they can develop improved treatments and learn how to target “problem” genes. They are aiming to restore proper brain function and mitigate against genetic expressions that are making addictions more likely. They are also hoping to help patients understand their risk and act more effectively to minimize it.
The bottom line
The question you might be asking yourself after learning about the genetic research into addiction is, naturally, if I inherited genetic risk, am I doomed to be an addict? The absolutely honest and great news is: definitely not. Your genes can increase your risk, but that is all they can do. It’s part of the picture—not even the most critical part for most people.
Your environmental risk factors are far more consequential when it comes to addiction. What does this mean? For starters, it means that whether or not you’ve got genetic risk factors, you should work hard to secure a safe, healthy environment for yourself, however, you can. Having certain genes might feel like you’re destined to be running a gauntlet your whole life, forced to beat the biological odds no matter what. However, if there’s one thing addiction science has shown, it’s that addiction is really far more about the totality of your circumstances.
Genetic information is great to have—why not maximize your chances? But overall, look toward your risk and protective factors, and seek professional help to escape what might feel like fate.