Weed Consumption Linked to Epigenetic Changes

Stephen Andrews
27 Nov 2023

A new scientific study suggests that the habitual use of cannabis can cause epigenetic changes in the human body. This is a rare investigation on the subject, and the researchers were interested to find out more about it because it might explain potential long-term health implications among cannabis users.

A study with more than 900 participants reveals that cannabis use may result in alterations in the human body’s epigenome. In the most basic definition, the epigenome is the record of chemical changes made to the DNA and histone proteins (histone proteins are the proteins that provide structural support to the chromosomes). 

The epigenome functions in a way that it activates and deactivates genes to change the way our bodies work. Whether recreational use of cannabis can affect the epigenome is an area that has not been much explored. Nevertheless, it’s important because it might implicate potential health outcomes from consistent consumption in the long run. 

One of the main reasons researchers went on to investigate any connections between cannabis and epigenome changes is the increased accessibility of marijuana with legalization. 

“Despite its growing popularity, as well as recent legalization by several states, the effect of marijuana on epigenetic factors has not been well studied,” said in a statement one of the senior researchers in the study, Lifang Hou. 

“We previously identified associations between marijuana use and the aging process as captured through DNA methylation,” said Hou, a medical doctor and epidemiologist from Northwestern University Feinberg School of Medicine. “We wanted to further explore whether specific epigenetic factors were associated with marijuana and whether these factors are related to health outcomes,” she added. 

The Study Detected Multiple Epigenetic Changes Due to Weed

The researchers in the study investigated blood samples taken five years apart from over 900 adults. The samples were provided through the CARDIA cohort group, which is a study that tracks the cardiovascular health of 5,000 subjects who were aged 18 to 30 years in 1985 and 1986.

The CARDIA participants have been asked about their marijuana use during different check-up sessions throughout the years. They have been asked if they use marijuana, how often they use, and if they have used any during the last 30 days. 

The epigenetic study has focused on participants who answered affirmatively on the marijuana use questions. Looking at each participant’s recent cannabis consumption and estimated cumulative use, Hou’s team performed DNA methylation profiling on retrieved blood samples. 

DNA methylation is a process that can reveal changes in the epigenome, if any. Both environmental and lifestyle factors can prompt methylation changes, which do not affect the genomic sequence of the DNA but it does change the activity of the genes. In turn, future generations may inherit these changes. 

The research group reportedly observed multiple associations between cumulative cannabis use and various epigenetic markers across time. DNA methylation markers associated with recent use and long-term use have been traced in both older and newer blood samples taken for screening. For example, the Northwestern University team detected 132 markers linked to recent use and 16 linked to cumulative marijuana use in the blood samples from the 20-year check-up in the CARDIA study. Similar numbers also came up in the 15-year samples. 

“Interestingly, we consistently identified one marker that has previously been associated with tobacco use, suggesting a potential shared epigenetic regulation between tobacco and marijuana use,” Hou said. “The observed marijuana markers were also associated with cell proliferation, infection and psychiatric disorders, however, additional studies are needed to replicate and verify these findings.”

The research does not establish any causal relationship between cannabis use and epigenetic changes, however. There’s no connection between the epigenetic changes and observed health outcomes either, said another researcher on the team, Drew Nannini, a postdoctoral fellow in Hou’s lab and the study’s first author. 

“The research has provided novel insights into the association between marijuana use and epigenetic factors, Nannini said. To determine if these associations are consistently observed in different population groups would require more research, Nannini added. More specifically, that means further studies that examine use of cannabis on age-related health outcomes and the long-term effect of marijuana on health. 

The study was published in the journal Molecular Psychiatry earlier this year. 

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Stephen Andrews