Researchers at Duke University compared sperm from two study groups of rats. The first group of rats was given tetrahydrocannabinol, otherwise known as THC, which is the psychoactive ingredient in the cannabis plant. The second group was the control group, and was given no drug. For the study, the team of scientists compared the sperm from these rat with the sperm cells of 24 adult human men who had either smoked marijuana weekly or had not used marijuana more than 10 times in their life.
The study found that in both of the test populations—the marijuana use groups—the drug affected how genes work in sperm cells.
Duke professor of gynecology, Susan Kay Murphy explains how DNA is, essentially, just a set of instructions that the body uses to make proteins. Genes are just a small subset of proteins. Our body can use methyl group chemical tags to join certain strands of DNA to specific regions. The study co-author also makes sure to note that the chemicals in THC do not actually mutate the genes, themselves, but they have the ability to affect how these genes are used by the body.
Or, you could say, THC can change the way the body chooses to follow genetic instructions; or whether to follow them at all.
Dr. Murphy continues to explain that cannabis affects many genes involved in sperm development along two pathways. One of these pathways regulates size while another affects cancer and tumor development.
Now, this does not meant that smoking cannabis will eventually—and definitely—lead to future children who are more vulnerable to cancer. Yes, this discovery might imply something like that but the data is still too preliminary to be so concerned. After all, the initial purpose of this pilot study was just to see if cannabis has any affect at all on the genes in sperm.
Indeed, senior study author Scott Kollins, PhD comments that the study only really confirms that cannabis use does, in fact, have some influence over the genetic profile in sperm, and that should motivate men to think about future cannabis use in relation to reproductive health. The Duke University professor in psychiatry and behavioral sciences adds that while we do not yet fully understand these implications, it something we should be thinking about as marijuana becomes more accessible.
The results of this study has been published in the journal Epigenetics.