A recent Queen’s study concluded that marijuana could have negative effects on male sexual health.

“Up until about two years ago, we were under the impression that cannabis could only affect receptors in the brain, but now we have observed that there are also cannabinoid receptors in the penis which are responsive to the THC in marijuana,” said Queen’s postdoctoral fellow Rany Shamloul.

When conducting his literature review, Shamloul came across findings from the last few years which indicated that the main psychoactive chemical compound in marijuana, tetrahydrocannabinol (THC), was responsible for causing a lack of sexual desire in both men and women. This was because it interfered with proteins known as cannabinoid receptors in the brain.

“This is an in depth review ... which went through all the articles published on marijuana and sexual dysfunction from [the] early ‘70s to 2010,” he said. “We analyzed details ... comparing the old data to the current data we have right now. We look both at ... basic animal studies, animal tissue labs and clinical studies.”

Shamloul’s study, which lasted from Feb. 2010 to June 2010, led him to suggest that THC can interfere directly with the muscle tissue of the penis.

When conducting the research, Shamloul examined studies that have used different animals such as rats and chimpanzees. He found that the strongest correlation between cannabis use and impotency came from the primates, indicating that the results could potentially be applied to humans. Shamloul said that theoretically, women’s sexual performance could also be adversely affected.

“The erectile tissue in the penis is similar to the tissue in the clitoris in that they both have cannabinoid receptors, so cannabis use could, in theory, affect a female’s ability to become sexually aroused as well,” he said, adding that currently the information about the connection between female arousal and cannabis use is scarce.

This is because so far most of the research in this field has been targeted towards males, as they tend to use cannabis much more frequently than females, he said.

Shamloul said his study only dealt with erectile dysfunction in the short term. A long-term goal would be to observe the results over five to six years.

Since previous studies exploring the effects of cannabis use on male sexual function have been limited, many have produced contradictory results, Shamloul said. While some studies have indicated that cannabis could have negative effects on erectile function, other investigations have found the opposite.

“The next step is to confirm the previous data by doing our own studies in a lab,” he said.

“We are currently formulating a grant and research protocol ... to try to find a way to fund the project. The project will ... monitor [men] over a number for years ... as young as teenage men [of] 13 and 14 up to 40 years old .... Hopefully we can do that over the next couple years.”

Shamloul said that although the facts may not necessarily make a conclusive statement about the relationship between sexual dysfunction and cannabis use, he does believe it’s an important issue that more people should be aware of, especially in Canada, where according to the 2007 World Drug Report by the United Nations Office on Drugs and Crime, approximately 16.8 per cent of people between ages 15 to 34 smoked marijuana in 2006, compared to the 3.8 per cent world average.

“A key message that needs to be passed to the younger generation is this: think twice before you smoke marijuana, because cannabis you use today may adversely affect your sexual performance in years to come.”

Shamloul’s findings will be published in the upcoming issue of Journal of Sexual Medicine, in late 2011.

— With files from Clare Clancy