A small study from McGill University suggests that people who use both tobacco and cannabis show distinct brain chemistry changes compared to cannabis-only users. Published in Drug and Alcohol Dependence Reports, the study said brain scans revealed higher levels of the enzyme FAAH, which regulates the endocannabinoid system and has been linked to addiction and anxiety. This may help explain why co-users often report worse mental health outcomes.
While the study did not include tobacco-only users and remains preliminary, researchers say the findings highlight a possible molecular mechanism behind the risks of combined use and could inform future treatments for cannabis use disorder.