Brain Chemistry Altered in Cannabis and Tobacco Users, Study Finds

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A new study led by McGill University researchers has discovered that people who use both cannabis and tobacco show distinct brain changes compared to those who use cannabis alone. These changes may help explain why people who use both substances often report increased depression and anxiety, and why quitting cannabis is harder for them than for people only using cannabis. The study, which used PET imaging, found that users of both substances had higher levels of the enzyme FAAH, which breaks down the naturally occurring "bliss molecule" anandamide, linked to anxiety, depression, and relapse.

Key Takeaways:

  • The study found that users of both cannabis and tobacco had higher levels of the enzyme FAAH, which breaks down anandamide, a naturally occurring "bliss molecule" linked to anxiety, depression, and relapse.
  • People who use both cannabis and tobacco show distinct brain changes compared to those who use cannabis alone.
  • The study suggests that the combination of cannabis and tobacco may alter brain chemistry in a way that worsens outcomes, such as depression and anxiety.
  • The researchers are now recruiting people who smoke cigarettes and people who vape nicotine in a new study to test whether the same brain changes occur without cannabis.
  • The study receiving funding from the National Institute of Mental Health may pave the way for the development of medications to treat cannabis use disorder.
  • The study found that 1 in 20 people who used cannabis in the past year in Canada are at risk for cannabis use disorder, and this figure rises to 1 in 3 among frequent users.
  • The researchers note that most studies have looked at cannabis and tobacco in isolation, leaving a gap that this study begins to address.

Statistics:

  • 1 in 20 people who used cannabis in the past year in Canada are at risk for cannabis use disorder (Source: Study).
  • 1 in 3 frequent cannabis users are at risk for cannabis use disorder (Source: Study).
  • Most people who use cannabis also use tobacco, according to the researchers.
  • The study analyzed PET brain scans from 13 young adults, with 8 smoking only cannabis and 5 smoking both cannabis and tobacco daily (Source: Study).
  • Cannabis users averaged just over 1 gram per day, while cigarette use ranged from 1 to 12 per day (Source: Study).

Sources:

  • "A preliminary investigation of tobacco co-use on endocannabinoid activity in people with cannabis use" by Rachel Rabin, Joseph Farrugia, Ranjini Garani and Romina Mizrahi in Drug and Alcohol Dependence Reports.
  • The National Institute of Mental Health.