Cannabis use causes epigenetic DNA changes

Smoking cannabis changes the expression of our genes, in other words our epigenome, as opposed to the genome (DNA). This is what emerges from a new scientific study, published in the journal Molecular Psychiatry (Source 1).

The study reveals that marijuana use is associated with changes in what is known as the human epigenome. We are talking about epigenetic modifications: it is not the genes themselves that are modified, but the expression of these genes. Simply put, our genes, our DNA (or genome), have a layer of complementary information that indicate whether or not the genes will be used. Certain genes can thus be expressed, overexpressed, or conversely, inactive, repressed, silenced, which will have consequences as to the proteins which will or will not be produced by the organism from these genes. If we inherit our genes from our parents, our epigenome can be modified by a whole host of environmental factors (pollution, diet, physical activity, social relationships and experiences, tobacco, drugs, etc.). Two identical twins thus share the same genome, but different epigenomes according to their lifestyles.

Here, researchers analyzed blood samples taken 5 years apart from more than 900 adults. The latter were asked about their recent cannabis consumption, but also their estimated cumulative consumption. By studying changes in participants’ gene expression, the team was able to link marijuana use to changes in the human epigenome. Please note, however: Correlation is not causation, so it remains to be proven that it is indeed cannabis use that is solely responsible for such epigenetic changes.

“In our study, we observed associations between cumulative marijuana use and multiple epigenetic markers over time”, said Lifang Hou, co-author of the study, in a communicated. “Interestingly, we have systematically identified a marker that has already been associated with tobacco use, suggesting a potential shared epigenetic regulation between tobacco and marijuana use. Marijuana markers observed were also associated with cell proliferation, infection and psychiatric disorders, however, further studies are needed to replicate and verify these results.”, she added. However, this study remains important for advancing research on the harmful effects of cannabis on health, but also for highlighting potential biomarkers making it possible to highlight recent cannabis consumption, within the framework of a drug testing.