Cannabis use might be linked to changes in the human body’s epigenome, according to a study involving more than 1,000 adults. The epigenome functions as a regulatory system, activating or deactivating genes to alter how our bodies operate.
“We observed associations between cumulative marijuana use and multiple epigenetic markers across time,” stated Lifang Hou, a preventive medical doctor and epidemiologist from Northwestern University Feinberg School of Medicine, when describing the findings published in July 2023.
Cannabis is widely used in the United States, with 49 percent of the population trying it at least once, according to Hou and her colleagues. Despite its legalization in some US states and other countries, the full impact on health remains unclear.
The researchers examined around 1,000 adults who had taken part in a long-term study where they were asked about their cannabis use over 20 years. Participants provided blood samples at the 15-year and 20-year marks, with the baseline starting when they were between 18 and 30 years old.
The research team analyzed the blood samples for epigenetic changes, focusing on DNA methylation levels in those who used cannabis recently or over a long period. DNA methylation involves adding or removing methyl groups from DNA, which can affect gene activity without altering the genomic sequence. Environmental and lifestyle factors, like drug use, can trigger these changes, potentially impacting future generations.
“We previously identified associations between marijuana use and the aging process as captured through DNA methylation,” Hou said. “We wanted to further explore whether specific epigenetic factors were associated with marijuana and whether these factors are related to health outcomes.”
The study found several DNA methylation markers in the 15-year blood samples linked to cannabis use—22 associated with recent use and 31 with cumulative use. In the 20-year samples, they identified 132 markers tied to recent use and 16 connected to cumulative use.
“Interestingly, we consistently identified one marker that has previously been associated with tobacco use,” Hou explained, suggesting a possible shared epigenetic regulation between tobacco and marijuana use.
Many of the identified epigenetic changes had been previously linked to health issues, including cellular proliferation, hormone signaling, infections, and neurological disorders like schizophrenia and bipolar disorder.
However, the study does not prove that cannabis use directly causes these changes or health problems. Drew Nannini, an epidemiologist from Northwestern University, noted, “This research has provided novel insights into the association between marijuana use and epigenetic factors.” He added that further studies are needed to determine whether these associations are consistently observed in different populations and to examine the potential long-term effects of marijuana on health.
