In a new study, researchers found that heavy cannabis use has an impact on human DNA but the effect is stronger in people who smoke tobacco as well.
The research was conducted by a team at the University of Canterbury (UC) and elsewhere.
The study examines how heavy cannabis use can lead to alterations in “DNA methylation”—chemical changes in the body that influence how our genes work.
The team says there is already strong evidence that chronic, heavy use of cannabis can increase the risk of mental health issues such as depression and schizophrenia. It is also associated with heart disease.
The current study shows how cannabis use is linked to changes in gene pathways that may explain the link between heavy cannabis use and those adverse health outcomes.
However, in terms of the effect on the genome and DNA methylation, cannabis appears to have a distinct and somewhat more subtle effect than tobacco.
It’s not altering gene pathways to the same extent, but it does affect them in very specific ways.
In the study, 48 heavy cannabis users were tested. Blood samples were taken when they were aged 28 and analyzed for DNA methylation differences between cannabis users and non-users.
The team found that the biggest changes were in those who smoked tobacco as well as cannabis, but there was also evidence of distinct and specific DNA alterations in those who smoked only cannabis, compared to non-users.
The most affected genes were identified as those involved in brain and heart function.
The team says assessing cannabis’s potential effect on DNA is timely.
It’s currently the most widely used illicit psychoactive substance in the world and this could be predicted to increase with decriminalization or legalization.
While tobacco has a stronger effect on DNA than cannabis, cannabis appears to exert specific effects on genes involved in brain and heart function. More research with larger sample size is needed.
The lead author of the study is UC College of Science lecturer Dr. Amy Osborne.
The study is published in Translational Psychiatry.
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