Cannabis use is less likely to cause DNA damage than tobacco use, according to a new epigenetic study recently published in the journal Translational Psychiatry.
Genes play an important role in how individuals respond to specific drugs, while also influencing the possible occurrence of addiction. Drug use is also known to cause temporary or permanent changes in the DNA of a user through a process called DNA methylation.
DNA methylation is a biological process in which methyl groups are added to a DNA molecule, creating a signal that can deactivate a specific gene. Scientists believe that errors in this methylation process can make an individual more vulnerable to diseases such as cancer, lupus, or muscular dystrophy, or make them more likely to pass on birth defects to their children.
Environmental factors such as drug or alcohol use, stress, diet, exercise, and bacterial infections can also alter the normal methylation process, increasing the risk of disease. Some of these changes appear to be permanent, while others are dynamic and temporary. For example, studies show that higher rates of DNA methylation are found in tobacco smokers, but these changes may return to normal when they quit.
A team of New Zealand researchers has been working to find out how cannabis alters the DNA methylation process compared to tobacco. The researchers used data from the Christchurch Health and Development Study, a longitudinal study that followed 1,265 children born in 1977 throughout their lives. These subjects were studied 24 times between birth and age 40, and researchers took a blood sample from most participants at age 28.
This study involved 96 participants who submitted a blood sample and described their lifetime drug use. The researchers divided the group of subjects into two groups: those who used both cannabis and tobacco, and those who used cannabis only. For cannabis-only users, the researchers restricted subjects to those who had used cannabis for three or more years, or who met the criteria for a cannabis use disorder.
Using blood samples, the researchers extracted DNA from each subject for analysis. The results linked cannabis to DNA methylation in some genes, but the results were less extreme than those caused by tobacco.
Consistent with previous reports on tobacco exposure, we observed the greatest differential methylation in cannabis with tobacco users in the AHRR and F2RL3 genes,” the study authors explain. “These changes, however, were not apparent in the cannabis-only group.
However, cannabis use was linked to increased DNA methylation in genes not affected by tobacco. These genes are linked to neural signaling and cardiomyopathy, which could potentially explain how cannabis could increase the risk of mental illness or heart disease.
The authors conclude that “the effects of cannabis use on mature human blood methylome differ from and are less pronounced than the effects of tobacco use, … larger sample sizes are needed to investigate this issue further.