Nicotine-cannabis transitions and nicotine abstinence among United States adults.

Background: Prior studies examining the association of cannabis use with nicotine abstinence did not distinguish between individuals co-using nicotine and cannabis versus those who switched from nicotine to exclusive cannabis use; these may have different effects on nicotine abstinence. We examined associations of cannabis use uptake with subsequent nicotine abstinence approximately 1 year later among adults using cigarettes and/or e-cigarettes.

Methods: Using six waves of the Population Assessment of Tobacco and Health Study (2013-2021), we assessed transitions from exclusive nicotine use pre-baseline (time t) to (1) exclusive cannabis use, (2) nicotine-cannabis co-use, (3) non-use of both nicotine and cannabis, and (4) continued exclusive nicotine use at baseline (t+1) as exposure variables. Analyses examined associations with nicotine abstinence (from both cigarettes and e-cigarettes) at 1-year follow-up (t+2).

Results: Among 8,382 adults (19,618 observations) reporting exclusive nicotine use pre-baseline, 1% transitioned to exclusive cannabis use, 9% to nicotine-cannabis co-use, and 9% to non-use of both drugs; 81% were still using nicotine exclusively at baseline. Transition to nicotine-cannabis co-use (6%) vs. exclusive nicotine use (10%) was inversely associated with nicotine abstinence at follow-up (adjusted relative risk [aRR]=0.68, 95%CI=0.55-0.83). Transition to exclusive cannabis use (72%) was positively associated with nicotine abstinence compared to continued exclusive nicotine use (10%) aRR=4.66, 95%CI=3.83-5.67), and with similar nicotine abstinence at follow-up (72%) compared to non-use of both drugs (65%; aRR=0.98, 95%CI=0.81-1.18).

Conclusions: Co-use of nicotine and cannabis was associated with lower nicotine abstinence. Switching to exclusive cannabis use was associated with similar or greater nicotine abstinence.