Cannabis Research is Ignoring Women, Says Study

Women are routinely left out of scientific cannabis studies, according to a new review. 

Instead of an even gender split, the majority of existing studies into cannabis and psychosis either over-sampled males or failed to report differences by sex.

After reviewing years of scientific literature, the authors concluded that this female exclusion could be skewing the scientific community’s understanding of the drug, as there is such limited information on how women react to the plant.  

Ian Hamilton, a senior lecturer in addiction at the University of York and lead author of the review, told Analytical Cannabis that this ostracism of women from cannabis-psychosis studies could be having an alarming detriment to future mental health treatments.  

“The vast majority of people who use cannabis will not experience a problem, but there is clearly a small group of people – men and women – who will. And obviously, in terms of cannabis, one of the most serious problems is psychosis.”

Cannabis is the most widely used drug among patients who experience first episode psychosis, and research has shown that consuming it may approximately double the overall risk of young people developing their first episode. 

But, conversely, the drug also shows promise in treating psychosis. One study by King’s College London concluded that cannabidiol (CBD), the renowned calming compound in cannabis, has anti-psychotic properties when given to young people experiencing distressing psychotic symptoms. Although it's worth noting that the group given CBD in that particular study consisted of just 6 female subjects compared to 10 males. 

“I'm concerned why researchers continue to overly focus on what happens to men when they use cannabis, given that millions of women around the world use it; it's not just men.”

This male cherry-picking has two main causes, according to Hamilton. One, the majority of those carrying out cannabis studies are men, which creates a subconscious bias around gender. And two, many participants for such studies were recruited from drug treatment centers, which are usually occupied by men.

“Male researchers dominate the field,” explained Hamilton. “So there are far more men in powerful positions in academia than there are women. And I think that's probably contributed to this bias, which I don't think is unique to drugs and cannabis. I think it's probably the case across all areas of health.”

“Plus, researchers tend to go into drug treatment centers to recruit participants,” he added. “And we know that those treatment centers are dominated by male patients. So straight away, you've got a pool of participants skewed towards men.”

While historically women have been a minority group among cannabis users, that imbalance is quickly changing in regions with legal recreational access. During its first year of lawful sales, the number of female cannabis consumers in California grew by 92 percent, according to the delivery app Eaze. And after examining the sales data from over 450,000 customers, the Californian company found that women occupied 38 percent of its market – a proportion set to increase to 50 percent by 2022. 

But Hamilton warns that this growing female cannabis consumer base is being underserved by the scientific community, which has overlooked the unique effects marijuana’s compounds can have on women. 

“We know that women, metabolically, have some differences to men and that they process drugs slightly differently,” he continued. 

“For example, we can see that estrogen and other hormones are making a difference. It might be that women are, in some ways, more immune to the effects of cannabis when it comes to problems like psychosis than men. But we just don’t know.”

The review published in Current Psychiatry Reports also highlights how the lack of cannabis studies conducted outside of North America and Europe could bias existing research. 

“With cannabis, we're not look at what happens to 20 people, we're looking at what happens to millions of people,” said Hamilton. “But it’s just a fact that most of the researchers in this field are either from America or Western countries, so they’re more likely to look at populations around them.”  

Ultimately, the study’s authors are calling for cannabis researchers to diversify their study subjects. They argue that including more women and people from Asia, Africa, and the Middle East in cannabis research will improve both the studies’ data and the future treatments that they may inspire. 

“I find it extraordinary not having this information about women,” said Hamilton “Because I think [having such information] would benefit men and women.”