Women tend to feel the same psychoactive effects of cannabis as men with a lower dose of THC, according to a study by Canadian researchers. A report on the study, “Sex differences in the acute effects of smoked cannabis: evidence from a human laboratory study of young adults,“ was published recently by the journal Psychopharmacology.

Justin Matheson, a Ph.D. candidate at the University of Toronto and lead author of the study, told psychology and neurosciences news website PsyPost that previous research has revealed differences in the way that men and women use cannabis.

“We know from population survey data that men are more likely to use cannabis than women, but it seems like women experience more severe cannabis-related harms,” said Matheson.

To conduct the research, which attempted to replicate the way people actually use cannabis, 91 test subjects smoked a single cannabis joint, with either 12.5% THC or a placebo. Test subjects had their THC levels and vital signs monitored and completed subjective effect scales and cognitive tests after smoking the joint. Test subjects were between 19 and 25 years old and consumed cannabis one to four times per week.

The researchers discovered that women smoked for the same length of time as men, although they consumed less of the joint. Despite the difference in consumption, however, men and women exhibited no difference in peak drug effects, mood, and cognitive effects.

“We found that women smoked less of a cannabis joint, had lower levels of THC in blood, yet experienced the same acute effects as men,” explained Matheson. “So, I think the main take-away is that women may need a lower dose of THC to get to the same degree of intoxication as men.”

Matheson noted that the study was designed so that the test subjects could smoke the amount of cannabis that they desired.

“When participants smoke to their desired high, we call this ‘titrating to effect,’” he said. “Titrating to effect is possible when smoking cannabis because THC delivery to the brain is very rapid with this route of administration, so users can feel the high as they are still smoking.”

“However, with other cannabis products like edibles or beverages that have a delayed onset of action, it is not possible to titrate to effect,” Matheson continued. “In these cases, women are likely at higher risk of experiencing acute harms.”

More Research Needed

Matheson noted that the study was subject to some limitations, including the differences between gender and sex.

“The major caveat here is that we considered sex as a binary biological variable (male vs. female) and we had no measure of gender,” he said. “Sex is a biological construct that represents things like sex chromosomes, hormones, anatomy, and physiology, while gender is a social and cultural construct that represents things like our gender identity (male, female, or gender-diverse) and the expectations that our societies have for us based on these identities.”

Matheson added that the study represents a first step to observing sex differences in the acute effects of cannabis. Determining the cause of those differences will require more research, which may reveal that both sex and gender are involved.

“For example, there’s evidence that estrogen (a sex hormone) influences the metabolism of THC, which could explain some of the sex differences in the metabolism of THC we see,” he said. “But we also know that gender identity influences drug use behaviors, which could relate to why we saw that women smoked less of the cannabis joint.”

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