Background: Although many sociodemographic and psychosocial factors have been identified as related to adolescent smoking, few studies have examined the role of nicotine-dependence (ND) symptoms. The objective was to study the association between ND symptoms and smoking status among adolescents in the early stages of the smoking onset process.
Methods: The McGill University Study on the Natural History of Nicotine Dependence is an ongoing 6-year prospective investigation of the natural history of ND among 1267 grade 7 students in ten Montreal high schools. The baseline response was 55.4%. Subjects for this cross-sectional analysis of baseline data, collected in 1999, included 241 past 3-month smokers (mean age [SD]=13.0+/-0.7 years at baseline). ND symptoms were measured in five indicators, including a measure based on the criteria for tobacco dependence in the International Classification of Diseases-10th Revision (ICD-10), the Hooked on Nicotine Checklist, and three symptom clusters (withdrawal, self-medication, and ND/cravings symptoms). The association between ND symptom indicators and each of sporadic, monthly, weekly, and daily smoking relative to less frequent smoking was investigated in multiple logistic regression analysis.
Results: Despite low cigarette exposure, 16.6% (95% confidence interval [CI], 11.9%-21.3%) of past 3-month smokers were tobacco dependent. The proportion increased from 0%, 3.1% (95% CI, 0.0%-9.2%), and 4.6% (95% CI, 0.2%-9.0%) among triers, sporadic smokers, and monthly smokers, respectively, to 19.4% (95% CI, 5.5%-33.3%) and 65.9% (95% CI, 51.9%-79.9%) among weekly and daily smokers, respectively. ND/cravings consistently distinguished each smoking category from less frequent smokers; the odds ratios (95% CI) for ND/cravings symptoms were 1.16 (0.99-1.35) in sporadic smokers; 1.17 (1.06-1.29) in monthly smokers; 1.34 (1.19-1.50) in weekly smokers; and 1.39 (1.22-1.59) in daily smokers.
Conclusions: These data challenge current smoking onset models, which suggest that ND develops only after several years of heavy or daily smoking. ND symptoms are associated, at least cross-sectionally, with increased smoking in adolescents. To increase the likelihood of being effective, tobacco-control programs for children and adolescents will need to take early ND symptoms into account.