Cannabis-Tobacco Combo Boosts Brain's Bliss Molecule

Twice as good = twice as bad.

Starter Stats

• In Canada, about one in 20 past-year cannabis users is at risk for cannabis use disorder. That number jumps to one in three for frequent users.

• Most cannabis users also smoke tobacco, despite declining tobacco rates.

• Cannabis use reported in the past year increased from 22% in 2018 to 26% in both 2023 and 2024.

---

McGill University researchers have uncovered the first human evidence that smoking both cannabis and tobacco alters brain chemistry, boosting levels of an enzyme that breaks down the "bliss molecule" anandamide. The finding could explain why dual users report more depression, anxiety, and difficulty quitting cannabis.

The study found that people who use both substances have higher FAAH enzyme levels compared to those who only use cannabis. This leads to reduced anandamide levels, which play a key role in mood and stress regulation.

“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.”

— Dr. Rachel Rabin, McGill Department of Psychiatry

Prior studies often examined cannabis or tobacco in isolation. The recent findings could help inform the development of new medications for cannabis use disorder, where current options are limited to behavioural therapies like counselling.

While the changes might stem from tobacco alone (as no tobacco-only group was included), the differences surprised researchers and suggest an interactive effect. A follow-up study is now recruiting cigarette smokers and nicotine vapers to isolate these impacts.

Read more →