Marijuana use has become increasingly common in recent years, especially as more states across the United States have legalized the drug for medical or recreational use.
Millions of people now use marijuana for a variety of reasons, including relaxation, pain relief, stress management, and treatment of certain medical conditions. As marijuana becomes more accepted in society, scientists are working to better understand how it affects the body, both in the short term and over many years.
A new study from researchers at Northwestern Medicine has revealed a surprising finding. The research suggests that marijuana use may be linked to changes in DNA-related processes that help control how genes work inside the body.
The study was published in the journal Molecular Psychiatry and provides new clues about the possible long-term biological effects of cannabis use.
Marijuana comes from the Cannabis sativa plant. It can be consumed in several different ways. Some people smoke dried cannabis flowers in hand-rolled cigarettes known as joints, while others use pipes, bongs, vaporizers, foods, drinks, or oils containing cannabis extracts.
The plant contains many active compounds, including tetrahydrocannabinol, commonly known as THC, which is responsible for most of the drug’s mind-altering effects.
According to the U.S. Centers for Disease Control and Prevention, marijuana is the most commonly used federally illegal drug in the country. Tens of millions of Americans report using it each year. Despite its widespread use, many questions remain about how cannabis affects long-term health.
To investigate this issue, the research team led by Dr. Lifang Hou studied more than 900 adults who had participated in a large long-term study focused on heart health. The researchers collected blood samples from participants and analyzed samples taken about five years apart. This allowed them to examine changes that occurred over time.
Participants were asked about their marijuana use, including recent use and estimated use throughout their lifetime. The scientists then examined DNA found in blood samples to determine whether marijuana use was associated with measurable biological changes.
The researchers focused on a process known as DNA methylation. DNA methylation is a natural mechanism that helps regulate how genes function. Small chemical markers attach to DNA and can influence whether certain genes are more active or less active.
Importantly, these changes do not alter a person’s genetic code. Instead, they affect how the information contained within genes is used by the body.
Scientists have become increasingly interested in DNA methylation because it may help explain how environmental factors such as diet, stress, pollution, smoking, and drug use influence health. Changes in DNA methylation have been linked to aging, cancer, heart disease, immune function, and neurological conditions.
The study found that marijuana use was associated with changes in several DNA methylation markers. Depending on how marijuana exposure was measured, researchers identified between 16 and 132 markers that appeared different among users. Many of these markers were located in genes involved in important biological functions.
Some of the affected genes were linked to cell growth and development. Others were connected to hormone regulation, immune system activity, and brain function. Researchers also found links to genes that have previously been associated with mental health conditions such as schizophrenia, bipolar disorder, and substance use disorders.
The findings do not prove that marijuana directly causes these DNA changes. Likewise, the study does not show that the changes lead to disease. However, the results reveal a clear association between marijuana use and measurable differences in biological processes that regulate gene activity.
This discovery raises several important questions. Researchers now want to understand whether these DNA changes remain for many years after marijuana use ends and whether they contribute to health problems later in life.
Future studies may also explore whether the observed changes help explain some of the mental health effects that have been reported among certain cannabis users.
The research may also have implications for aging and neurodegenerative diseases. Scientists are increasingly studying how DNA methylation affects conditions such as Alzheimer’s disease, depression, and cognitive decline.
Understanding how marijuana influences these biological pathways could provide valuable information about both risks and potential benefits.
As cannabis becomes more widely available, understanding its long-term health effects is becoming increasingly important. Many people assume that because marijuana is natural or legal in some places, it is completely harmless. However, scientists emphasize that much remains unknown about how regular cannabis use affects the body over decades.
This study represents an important step toward filling those knowledge gaps. While it does not provide definitive answers, it suggests that marijuana may influence human biology in ways that researchers are only beginning to understand.
By uncovering links between cannabis use and DNA-related processes, scientists hope to gain a clearer picture of how marijuana affects health over the long term.
If you care about heart health, please read studies about how eating eggs can help reduce heart disease risk, and herbal supplements could harm your heart rhythm.
For more health information, please see recent studies about how drinking milk affects risks of heart disease and cancer, and results showing strawberries could help prevent Alzheimer’s disease.
The research was published in the journal Molecular Psychiatry.
Copyright © 2026 Knowridge Science Report. All rights reserved.
