High-potency cannabis use leaves a unique mark on DNA

Researchers have discovered that the use of high-potency cannabis (defined as having THC content of 10% or greater) leaves a distinct mark on DNA, providing valuable insights into the biological impact of cannabis use.

The research team explored the effects of cannabis use on DNA methylation — a chemical process detected in blood samples that alters how genes are functioning (whether they are switched ‘on’ or ‘off’). DNA methylation is a type of epigenetic change, which means it alters gene expression without affecting the DNA sequence itself, and is considered a vital factor in the interplay between risk factors and mental health.

A laboratory team at the University of Exeter conducted complex analyses of DNA methylation across the whole human genome using blood samples from both people who have experienced first-episode psychosis and those who have never had a psychotic experience. The researchers investigated the impact of current cannabis use, including frequency and potency, on DNA of a total of 682 participants. Most of the cannabis users in the study used high potency cannabis more than once a week (defined as frequent use) and had first used cannabis at age 16 on average.

Their analysis, which was published in the journal Molecular Psychiatry, showed that frequent users of high-potency cannabis had changes in genes related to mitochondrial and immune function — particularly the CAVIN1 gene, which could affect energy and immune response. These changes were not explained by the well-established impact that tobacco has on DNA methylation, which is usually mixed into joints by most cannabis users.

“This is the first study to show that frequent use of high-potency cannabis leaves a distinct molecular mark on DNA, particularly affecting genes related to energy and immune function,” said first author Dr Emma Dempster, a senior lecturer at the University of Exeter.

“DNA methylation, which bridges the gap between genetics and environmental factors, is a key mechanism that allows external influences, such as substance use, to impact gene activity. These epigenetic changes, shaped by lifestyle and exposures, offer a valuable perspective on how cannabis use may influence mental health through biological pathways.”

The research also showed the effect of cannabis use on DNA is different in people experiencing their first episode of psychosis compared to users who have never experienced psychosis. This suggests there could be potential for DNA blood tests to help characterise those cannabis users at risk of developing psychosis to inform preventative approaches.

“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,” said senior author Professor Marta Di Forti, from the Institute of Psychiatry, Psychology & Neuroscience at King’s College London.

“Future research needs to explore if the DNA signature for current cannabis use, and in particular the one of high-potency types, can help identify those users most at risk to develop psychosis, both in recreational and medicinal use settings.”

Image credit: iStock.com/Md Shahadat Hossain