London, Oct 27 : Hormones could be the reason why cannabis affects women differently than men, brain studies on animals and humans suggest.
The studies showed that sex differences in response to cannabis are not just socio-cultural, but biological too.
The findings showed that men are up to four times more likely to try cannabis and use higher doses, more frequently.
"Male sex steroids increase risk-taking behaviour and suppress the brain's reward system which could explain why males are more likely to try drugs including cannabis," said Liana Fattore, Senior Researcher at the National Research Council of Italy.
"This is true for both natural male sex steroids like testosterone and synthetic steroids like nandrolone."
But despite lower average cannabis use, women go from first hit to habit faster than men.
In fact, men and women differ not only in the prevalence and frequency of cannabis use, pattern and reasons of use, but also in the vulnerability to develop cannabis use disorder.
"Females seem to be more vulnerable, at a neurochemical level, in developing addiction to cannabis," Fattore explained, in the paper published in the journal Frontiers in behavioural Neuroscience.
"As a result, the interactions between the endocannabinoid system and the brain level of dopamine -- the neurotransmitter of "pleasure" and "reward" are sex-dependent."
The inconsistency of conditions in these studies greatly complicates interpretation of an already complex role of sex hormones in the endocannabinoid system and cannabinoid sensitivity.
However, the human data so far is consistent with the idea that oestradiol regulates the female response to cannabinoids.
As in animals, human males and females are diverse in their genetic and hormonally driven behaviour and they process information differently, perceive emotions in different ways and are differently vulnerable to develop drug addiction.
"Blood levels of enzymes which break down cannabinoids fluctuate across the human menstrual cycle, and imaging studies show that brain levels of cannabinoid receptors increase with ageing in females -- mirroring in each case changes in oestradiol levels," Fattore said.