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A new study from UCLA Health suggests that men and women who use marijuana occasionally may experience different effects, with men reporting stronger reactions to the drug than women with similar use habits. The research, published in the journal Neuropsychopharmacology, involved 44 healthy adults ages 21 to 55, evenly split by sex and cannabis use frequency.
Participants attended three sessions in which they smoked cannabis containing either no THC, a lower amount, or a higher amount, without knowing which one they received. The researchers found that among occasional cannabis users, men felt more intoxicated, sedated, and impaired compared to women. Men in this group also reported more unpleasant effects, such as anxiety, and had a greater increase in heart rate after smoking active cannabis. Despite these stronger effects, blood tests showed similar THC levels between men and women.
The study challenges earlier research that suggested women are more sensitive to cannabis. "Much of what we thought we knew about sex differences in cannabis effects came from animal research and from human studies that pooled data from different trials. When we designed a study to look at sex and frequency of use at the same time, and controlled for hormones, the picture changed," Dr. Ziva Cooper, the study’s principal investigator and director of the UCLA Center for Cannabis and Cannabinoids, said in a press release.
Researchers controlled for hormonal differences among women by scheduling their participation during the same phase of their menstrual cycles and ensuring none were using hormonal birth control. The findings indicate that a person’s cannabis use history—how often they use the drug—may play an important role in how they respond. Dr. Stephanie Lake, the study's lead author, said, "Sex and cannabis use history can both shape how someone experiences the effects of cannabis, and studying both together is key to understanding who is most at risk of higher-risk, unpleasant, or beneficial experiences from cannabis."
The study also found that men and women who used cannabis frequently showed similar responses to the drug, and frequent users overall were more likely to say they liked the effects and wanted to use cannabis again. Frequent users, regardless of sex, were more likely to increase their intake during the study sessions.
The researchers emphasized the need for larger studies to confirm these results and to better understand whether men and women develop tolerance to cannabis differently, which could affect the risk of developing cannabis use disorder.
With cannabis use rising among women, the researchers believe these findings may help guide future prevention and treatment strategies. The team is now studying higher-potency cannabis products and older adults.