Marijuana use is becoming more common in the United States. As of recent data, nearly 1 in 5 Americans—about 18%—have used marijuana at least once. With more states legalizing it, interest in how marijuana affects our health is growing quickly.
A new study from Northwestern Medicine, published in Molecular Psychiatry, offers fresh insight into what might be happening inside our bodies when we use marijuana. The findings suggest marijuana use could be linked to changes in our DNA—a discovery that may help explain some of the drug’s long-term effects on health.
Marijuana comes from the Cannabis sativa plant and can be used in several ways. Some people smoke it in hand-rolled cigarettes called joints, while others use pipes or bongs. Some even brew it into tea or mix it into food.
According to the Centers for Disease Control and Prevention (CDC), 48.2 million people in the U.S. used marijuana in 2019. This makes it the most commonly used drug in the country.
Despite its growing popularity and legal status in many places, there’s still a lot we don’t know about marijuana’s health effects. That’s why researchers are now turning their attention to how the drug might impact our bodies at the genetic level.
The research team, led by Dr. Lifang Hou, collected blood samples from over 900 adults who had already taken part in a large study on heart health. They analyzed blood samples taken five years apart to track any changes over time.
The researchers asked participants about their recent marijuana use and tried to estimate their total use over a lifetime. Then they examined the DNA in their blood to look for changes.
What they found was surprising: marijuana use was linked to changes in a biological process called DNA methylation. This is a natural process where small chemical tags attach to DNA, influencing which genes are turned on or off. These changes don’t change the DNA sequence itself, but they can affect how the body works.
The researchers identified between 16 and 132 DNA markers that were different in people who used marijuana. These markers were located in genes related to cell growth, hormone function, immune response, and mental health conditions like schizophrenia, bipolar disorder, and substance use disorders.
It’s important to note that the study does not prove marijuana causes these DNA changes—or that the changes lead to health problems. But it does show a clear link between marijuana use and measurable changes in how the body may regulate certain genes.
This opens up new questions: Could long-term marijuana use increase the risk of some diseases? Could these DNA changes help explain mental health or immune system effects seen in some users? More research is needed to answer these questions.
As marijuana becomes more widely accepted and used, it’s critical to understand not just its short-term effects but also what it may do to our bodies over time. Studies like this one help fill that gap by pointing to possible long-term impacts on gene regulation.
The researchers say their findings could help guide future studies on marijuana’s effects, especially in areas like mental health and aging. For example, scientists may now explore whether DNA methylation linked to marijuana use plays a role in diseases like Alzheimer’s or depression.
This study doesn’t give all the answers—but it’s an important first step. It shows that marijuana use might influence our biology in ways we’re just beginning to understand. As more people turn to cannabis for both medical and recreational reasons, it’s more important than ever to keep learning about its potential effects.
If you’re interested in marijuana and health, you might want to explore related studies on how cannabis may affect heart health, how CBD might help protect the brain from aging, or how medical cannabis could improve depression and quality of life.
Marijuana’s growing popularity makes this kind of research vital—so we can all make informed decisions about our health.
If you care about smoking, please read studies about smoking may increase heart disease risk by 200% and e-cigarette smoke may cause lung cancer and bladder disease.
For more health information, please see recent studies about the cause of weight gain after smoking cessation, and results showing smoking may cause white scars on the brain.
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