Smoking reduction is associated with lower alcohol consumption and depressive symptoms among young adults over one year.

Background: This secondary analysis examined whether smoking reduction among young adults participating in a Facebook-based smoking cessation intervention study was associated with corresponding reductions in alcohol consumption and depressive symptoms.

Methods: Participants were young adults who smoked and engaged in heavy episodic drinking (HED). Alcohol consumption (AUDIT-C, days of HED), depressive symptoms (PHQ-2), and past-month cigarettes per day (CPD) were self-reported at baseline and 12 months (N = 150). Linear regression estimated the relationship between the mean change in CPD and mean changes in alcohol consumption and depressive symptoms.

Results: CPD, alcohol consumption, and depressive symptoms decreased significantly between baseline and 12 months. The adjusted mean reduction in CPD was significantly associated with mean reductions in AUDIT-C (Beta [β] = 0.09, 95 % confidence interval [CI] = 0.04-0.14), days of HED (β = 0.17, 95 % CI = 0.04-0.29) and PHQ-2 (β = 0.05, 95 % CI = 0.01-0.08). Smoking abstinence (n = 48) was associated with a significantly larger mean reduction in AUDIT-C compared to a ≥50 % reduction (n = 45) (-2.9 vs -1.7 points, p = 0.03) or <50 % reduction in CPD (n = 57) (-2.9 vs -1.1 points, p < 0.01). The mean reduction in AUDIT-C did not differ between a ≥50 % reduction and <50 % reduction in CPD (-1.7 vs.-1.1 points, p = 0.18). Mean reductions in days of HED and the PHQ-2 did not differ according to the level of reduction in CPD.

Conclusion: Smoking reduction was associated with reductions in alcohol consumption and depressive symptoms. Reductions appeared to be greater for those who achieved abstinence compared to a reduction in smoking.