Study Identifies Link Between High-Potency Cannabis Use and DNA Changes, Psychosis

Learn about the latest research on the biological and mental health implications of frequent high-potency cannabis use.

James MacWilliams prunes a marijuana plant that he is growing indoors in Portland, Maine, on Dec. 13, 2017. Robert F. Bukaty/AP Photo

A recent study has found that frequent use of high-potency cannabis can leave measurable changes to human DNA, raising concerns about the mental health impacts of increasingly available and more potent marijuana products.

Researchers discovered alterations in genes linked to mitochondrial and immune function among regular users of cannabis with concentrations of tetrahydrocannabinol (THC), the main psychoactive compound found in the cannabis plant, of more than 10 percent, potentially affecting energy metabolism and immune responses.

Adverse Psychological Effects Already Linked to Cannabis

A large number of Americans—about 129 million people—claimed to have used marijuana at some point in their lifetime. As various states pass legalization measures, this number is projected to rise.

There is also a growing body of evidence showing that this trend could have serious consequences for mental and physical health.

Research shows that marijuana joints deliver at least four times as much tar to the lungs as comparable tobacco cigarettes.

A 2019 study published in The Lancet Psychiatry indicates that daily use of cannabis, particularly high-potency cannabis, has a strong correlation with the onset of psychosis.

The findings suggest a significant increase in new psychosis cases in cities where high-potency cannabis is readily available.

“Our findings are consistent with previous studies showing that the use of cannabis with a high concentration of THC has more harmful effects on mental health than the use of weaker forms,” Dr. Marta Di Forti, lead author from the Institute of Psychiatry, Psychology & Neuroscience, said in a statement. “They also indicate for the first time how cannabis use affects the incidence of psychotic disorder at a population level.”

New Insights on High-Potency Cannabis and DNA

Now, in a recent study published in Molecular Psychiatry, Di Forti and her team discovered that high-potency cannabis can leave a distinct mark on human DNA. This is the first study to demonstrate measurable effects of high-potency cannabis on human biology, they noted.

The research focused on DNA methylation, a chemical process that alters gene expression without modifying the DNA sequence, using blood samples from 682 participants, including 188 current cannabis users and 494 people without any history of use.

The study analyzed data from two cohorts: the GAP study, targeting first-episode psychosis patients in South London, and the EU-GEI study, which included patients and healthy controls from multiple European countries and Brazil.

According to the results, the participants categorized as frequent cannabis users reported beginning their cannabis usage at an average age of 16, primarily consuming high-potency cannabis more than once a week.

The analysis identified that frequent users of high-potency cannabis, defined as having a delta-9-tetrahydrocannabinol (delta-9-THC) content of 10 percent or more, displayed alterations in the CAVIN1 gene, which is associated with mitochondrial and immune function. These changes could potentially affect energy metabolism and immune responses.

Delta-9-THC is the most abundant form in the THC class of cannabinoids and is known for its potent psychoactive properties.

The findings also suggest that the effects of cannabis on DNA differ between people experiencing their first psychotic episode and those with no such experience. This raises the prospect of developing DNA blood tests to identify cannabis users who may be at risk for psychosis.

“With the increasing prevalence of cannabis use and more availability of high potency cannabis, there is a pressing need to better understand its biological impact, particularly on mental health,” Di Forti said in a statement.

Co-occurring Mental Health Issues and Cannabis Use

Mental health problems and substance use disorders sometimes go hand-in-hand. Substance use can trigger mental health symptoms, and mental health conditions can lead to substance use as a form of self-medication, according to the Substance Abuse and Mental Health Services Administration. They share underlying causes, including genetic factors, brain changes, and trauma. More than a quarter of adults with serious mental health conditions also struggle with substance use, particularly those with depression, anxiety disorders, schizophrenia, or personality disorders.

The Epoch Times consulted Dr. Matthew Sherman, chief of adult outpatient psychiatry and behavioral health at Stony Brook Medicine, regarding the relationship between cannabis use and other mental health disorders. Based on his experience, co-occurring cannabis use with mental health disorders is prevalent and often adversely affects treatment outcomes, he said.

“I believe that any psychoactive substance such as cannabis influences treatment outcomes greatly in a negative way,” he added, highlighting the interactions with psychotropic medications and the effects of cannabis intoxication or withdrawal on patients’ mental health.

Ethical Considerations of DNA Testing for Psychosis Risk

There are many ethical considerations when using DNA to identify risks, Sanam Hafeez, neuropsychologist and director of Comprehend the Mind, a provider of neuropsychological assessments and evaluations in New York City, told The Epoch Times.

“For one, this type of DNA imprinting, whilst possibly valuable, opens the door to ‘what else’ can change my genes,” she said.

Should DNA testing become more widespread, it could have repercussions for the mentally ill, such as “having their DNA misused or even studied without consent, legal implications, and [potential for] gene modification using substances like cannabis,” Hafeez said.

Conversely, Sherman expressed optimism about the potential of DNA testing to benefit patients.

“I think that this has the potential to be a very practical test to perform for our patients,” he said. “Ethically, I think that this could only benefit our patients by being able to identify those who are more at risk for developing psychosis with cannabis use.”

He added that he’s “quite intrigued” by the findings, “as we don’t currently have a method outside of clinical evaluation and risk factors such as family history to determine which ... patients may be at higher risk for developing psychosis.”