In an effort to better understand the dosing potential of medicinal marijuana, researchers have turned their attention to how different sexes may be affected by THC, a key ingredient in cannabis. Interestingly, they quickly found that the female hormone estrogen may play a key role in THC sensitivity.

The study was funded by the National Institute on Drug Abuse and partially plays off previous work that claims that women are more prone to cannabis abuse and dependencies than men.

Unlike with hard drugs, cannabis dependency is largely seen as a mental illness, and can lead to withdrawal symptoms such as irritability, difficulty sleeping and smaller appetite - all of which have been seen to vary depending on an individual's cannabis habits.

That may seem like common sense to most, where if you use anything to aid sleep or build an appetite and then take it away, it may lead to similar withdrawal symptoms. However, this past work has also found that these symptoms tend to affect women more severally, indicating that THC may pack a bigger punch for females.

To see if this was true, Rebecca Craft of Washington State University led her colleagues in a recent study of THC sensitivity in lab rats.

This is the kind of work that Craft has been doing for quite some time, in which she and her team "routinely manipulate hormones and follow females across their cycles to see if their drug sensitivities change along with their hormones."

"And they do," she added in a recent release, "very frequently."

According to study results published in the journal Drug and Alcohol Dependence, estrogen is the cause.

"What we're finding with THC is that you get a very clear spike in drug sensitivity right when the females are ovulating - right when their estrogen levels have peaked and are coming down," she explained.

Interestingly, while females are more sensitive to the drug, they also build a tolerance to it faster, meaning that while females can be exposed to less THC than males for the same effect, they will increasingly need more.

Craft says she and her team hope to use their knowledge to help medicinal marijuana users suffering from extreme and debilitating pain - such as those suffering from Crohn's disease or multiple sclerosis.

By better understanding sensitivities and tolerances, they hope to better advise proper and safe dosing.