A recent review of existing cannabis research showed that we still know very little about how cannabis interacts with the female body. And that's because cannabis researchers don't include women in their studies.
For instance, we have nearly 100 years worth of research on the connection between cannabis and psychosis, but very few of those studies involved female subjects. So we have almost no idea of what the psychological impacts of cannabis on women are.
"The research to date is completely biased towards men, a situation not helped by mainly men being in control of this research," Ian Hamilton—the study's co-author and a Health Sciences lecturer from the University of York—told the Daily Mail. "Research is letting women down."
One of the biggest reasons why women seem to be largely excluded from cannabis research is because most study participants are people who are attending addiction treatment programs. And the vast majority of those people are men.
"For researchers it's a lot of easier to get people in treatment because they are already there," explained Hamilton. "But the problem of doing that is there is more men in treatment than women, so this is also added to this distorted view of cannabis and psychosis."
As a result, we don't understand the effects of cannabis on women very well. And that probably won't change anytime soon as researchers continue to focus on psychosis instead of other issues related to the effects of cannabis.
"I think a lot of money has been wasted replicating research that keeps trying to find and pin down a causal relationship between cannabis and psychosis," he said. "But it's never going to happen. It's too complicated."
Hamilton's own past research suggests that the possibility of developing cannabis-induced psychosis is very low anyhow. So in Hamilton's mind, the research funding would be better spent trying to understand the particular risks and benefits cannabis brings to women.