A new, small-scale study has uncovered unique changes in brain chemistry among individuals who use both tobacco and cannabis, potentially explaining why this combination often leads to more severe addiction and mental health challenges compared to using either substance alone. The findings highlight a crucial step in understanding the complex interplay between tobacco and cannabis and could inform future treatment strategies.
The Research: A Preliminary Look at Brain Chemistry
Researchers at McGill University conducted a preliminary investigation comparing the brains of individuals who used only cannabis to those who used both tobacco and cannabis. The study involved just eight participants who used cannabis exclusively and five who used both tobacco and cannabis. Brain scans revealed a significantly higher level of a key enzyme, fatty acid amide hydrolase (FAAH), across multiple brain regions in the group using both substances.
What is FAAH and Why Does it Matter?
FAAH is an enzyme that interacts with the body’s endocannabinoid system – a network of receptors and molecules that plays a vital role in regulating various functions, including mood, pain perception, and appetite. It closely controls levels of anandamide, a neurotransmitter associated with feelings of bliss or joy. Recent research in animal studies suggests that FAAH may contribute to nicotine reward systems in the brain, but this link needs to be confirmed in human studies. Importantly, genetic variations in the FAAH gene have been associated with increased risks of drug abuse, addiction, and anxiety.
Potential Explanation for Worse Outcomes
“This is the first evidence in humans of a molecular mechanism that may underlie why people who use both cannabis and tobacco experience worse outcomes,” says lead author and psychology researcher Rachel Rabin from McGill University. The association is particularly intriguing because prior research has shown a concerning trend: young people in the US who use both tobacco and cannabis are more likely to report mental health problems compared to those who use only one substance.
Limitations and Future Research
While the findings are promising, researchers caution that this is a small, preliminary study. Further research is needed to determine whether these brain changes are directly caused by tobacco, if cannabis exacerbates them, and whether they increase a person’s risk of mental health issues. It is also possible that tobacco alone could be responsible for these changes, a possibility the study was not designed to explore.
The Widespread Combination and its Impact on Research
The combination of tobacco and cannabis is surprisingly common. Estimates suggest that up to 80% of cannabis users also use tobacco products. This overlap complicates research efforts attempting to understand the individual effects of each substance, influencing studies on lung diseases, mental health, brain function, and cognitive abilities. Currently, most research in this area is observational, meaning it can identify correlations but cannot establish cause and effect. This type of study also often fails to account for the amount of tobacco or cannabis used, further limiting the ability to draw definitive conclusions.
Looking Ahead: Potential for Treatment
“What surprised us was how strong the effect was, and how different it was from those who only used cannabis, compared to those who used both tobacco and cannabis,” adds co-author and psychiatrist Romina Mizrahi from McGill. Identifying this molecular mechanism is an important step toward finding new targets for medications that treat cannabis use disorder, especially among individuals who use tobacco alongside cannabis. Further studies will provide a more complete understanding of this complex interplay and pave the way for more effective interventions.
In time, more studies will help determine the true impact of combined tobacco and cannabis use on brain health and mental well-being.
The findings underscore the need for more rigorous research to disentangle the effects of each substance and understand the consequences of their combined use, ultimately leading to improved treatment options for those struggling with substance use disorders
