WSU study finds gender gap in effects of pot

Call it the marijuana gap.

Men and women may respond differently to the effects of pot’s active ingredient, THC, according to new research by a Washington State University professor. In experiments on lab rats, females were more sensitive to the pain-relieving qualities of the drug, but quicker to develop a tolerance to it than the males. Other studies have suggested that females are more susceptible to negative effects of the drugs and experience less of an increase in appetite.

But what we know about marijuana and women is still very sketchy – because there has been a dearth in research on both marijuana and sex differences in drug response.

“Drug research, and in fact all kinds of biomedical research, has largely ignored females for many, many, many years,” said Rebecca Craft, a professor of psychology at WSU.

Craft has been an exception, working on questions of sex-differences in drug response for two decades. Almost all drug studies are conducted on males, largely because it’s much simpler for researchers to avoid the hormone swings that are part of female biology and that can affect drug response. That’s changing as the scientific community is recognizing the need to study women, and the National Institutes of Health is requiring it. But so far, science has produced a lot of drug research that measures only males.

“That means male mice, male rats, male monkeys, male humans,” Craft said.

Craft’s research on the differences between genders in drug responses clarifies why this might be a problem.

“I actually thought there wouldn’t be very many,” she said. “I’ve been surprised by how many there have been.”

Her most recent research found that female rats were more sensitive to the pain-relieving qualities of THC than males, and that their sensitivity peaks right as they are ovulating, “right when their estrogen levels have peaked and are coming down,” Craft said. The female rats were also more likely to develop a tolerance for the drug, requiring higher doses to feel the same effect. Tolerance is one element of drug dependency; though marijuana is less addictive than alcohol or cocaine, it can still cause dependency in some users, Craft said.

One suggestion of her research is that women might be more susceptible to the negative effects of pot: paranoia, anxiety and addiction. Given the potency of modern marijuana and the legalization of recreational marijuana, these differences could be significant.

Other studies have shown sex differences in marijuana effects, as well. A 2013 paper by a pair of Columbia University researchers found that among daily pot smokers, women tended to report more of the “abuse-related effects” – saying the drug felt good and they wanted to use it again. That means women may have an “enhanced vulnerability” to dependence.

But, as with almost all marijuana research, there are more questions than answers. Because the feds have classed pot as a Schedule I drug – like heroin – funding for research has been thin. As more states approve medical and recreational marijuana, though, that seems to be changing, Craft said.

Still, drawing broad conclusions can be difficult. Many of the studies are on animals, which don’t always translate directly to humans, and the overall paucity of research means that suggestive studies don’t have as much replication and confirmation as they call for. When these studies enter the public realm, they inevitably become reduced and trivialized.

Because pot news is catnip for the media – including this member of the media – Craft’s study has gotten a lot of attention this week. It has often been boiled down to: “Women get higher, men get the munchies more.” While there are studies that suggest both, they are far from conclusive.

For one thing, Craft’s work involves lab rats, not women; the results may or may not translate. The “munchies” research – which was conducted by someone else – is also something that is mostly hinted at in an animal study.

“We know the drug gives men and women the munchies,” Craft said. “Whether it’s a bigger effect in men than in women, we really don’t know yet in humans.” The munchies question is more than a chance to make a Frito-Lay joke. Craft and other drug researchers are primarily interested in marijuana as a potential medicine; the way it affects appetite has potentially serious applications.

There’s a lot left to discover. Craft thinks that the legalization of medical marijuana and marijuana research will loosen up the purse strings of research funding.

“We are right at the beginning,” she said. “I think we’re going to start finding out a lot more, and we won’t have to rely so much on anecdotal reports.”