Background

Developmental relationships between tobacco use and suicide-related behaviors (SRB) remain unclear. Our objective was to investigate the longitudinal associations of tobacco use in adolescence and SRB in adulthood. Methods

Using a prospective design, we examined whether tobacco use in adolescence is associated with SRB (intentional self-injury, suicide ideation) in young adulthood in a population-based sample of 1330 twins (626 males, 704 females). The baseline and follow-up data were collected by professionally administered semi-structured poly-diagnostic interviews at ages 14 and 22, respectively. Results

After adjusting for multiple potential confounders, those who reported early-onset of regular tobacco use had a significantly increased risk for intentional self-injury, such as cutting or burning, at age 22 (adjusted odds ratio [AOR] 4.57, 95% CI 1.93–10.8) in comparison to those who had not at all initiated tobacco use. Also, daily cigarette smoking at baseline was associated with future intentional self-injury (AOR 4.45, 95% CI 2.04–9.70). Early-onset tobacco use was associated with suicidal ideation in females (AOR 3.69, 95% CI 1.56–8.72) but not in males. Considering any SRB, baseline daily smokers (AOR 2.13, 95% CI 1.12–4.07) and females with early onset of regular tobacco use (AOR 3.97, 95% CI 1.73–9.13) had an increased likelihood. Within-family analyses among twin pairs discordant for exposure and outcome controlling for familial confounds showed similar, albeit statistically non-significant, associations. Conclusion

Early-onset tobacco use in adolescence is longitudinally associated with SRB (intentional self-injury and/or suicide ideation) in young adulthood, particularly among females. Further investigation may reveal whether this association has implications for prevention of SRB in adolescence and young adulthood.