For the first time, chemical changes in the brain associated with the simultaneous consumption of cannabis and tobacco have been identified in humans.
The discovery, by researchers at the Douglas Research Center at McGill University, in Canada, in Drug and Alcohol Dependence Reports, may explain why those who use both substances tend to have higher levels of depression and anxiety, as well as greater difficulty in giving up consumption, specifically, of cannabis.
Researchers observed that people who consume both substances show significant brain differences compared to those who only consume cannabis.
“This is the first evidence in humans of a molecular mechanism that could be behind the worst results observed among cannabis and tobacco users”, say the researchers, cited by .
Using positron emission tomography (PET) scans, scientists found that participants who smoked both cannabis and tobacco had higher levels of the FAAH enzyme — responsible for the degradation of anandamide, a natural compound known as the “happiness molecule” for regulating mood and stress. An increase in FAAH translates into lower anandamide activity, a pattern already associated with anxiety, depression and a greater likelihood of relapse during attempts to stop consumption.
The study analyzed 13 young adults: eight who only consumed cannabis and five who also smoked cigarettes daily. Although the data did not include a group of tobacco-only smokers, the researchers believe the results indicate a joint effect of the two substances.
The discovery could lead to the creation of concrete medicines to treat the problem. Currently, the only approaches available are based on behavioral therapies, such as psychological counseling.
The team is now preparing a new study with smokers and e-cigarette users to assess whether the same brain changes occur in the absence of cannabis.
