Cortisol Concentration as Predictor of Tobacco Initiation in Adolescents: Results From a Population-Based Swedish Cohort

Purpose: Stress potentiates the smoking reward, decreases the ability to resist smoking, and increases the risk of smoking relapse in adulthood. This study aimed to clarify if salivary cortisol, as an indicator of stress, may be prospectively associated with the onset and phenotype of tobacco use in adolescents. Methods: This study was based on a cohort of Swedish adolescents, among whom saliva specimens were collected from a nested sample. We included adolescents with salivary cortisol measurements and without a history of tobacco use (n = 381, aged 13–14 years). Quartiles of morning and afternoon cortisol concentration and cortisol area under the curve were considered as predictors. We categorized tobacco use according to the product mainly used: cigarette smoking, snus use, or either type of tobacco. For each product use, two outcomes were considered: initiation and duration of use. Poisson regression models were used to calculate rate ratios. Results: A quartile increase in morning cortisol levels and cortisol area under the curve was consistently associated with a 1.2- to 1.4-fold increased risk of initiation of cigarette smoking snus use, or any tobacco use. Similar results were obtained examining the dose–response relationship and using the duration of use as outcome. No associations were apparent between afternoon cortisol concentration and any of the outcomes. All associations were similar between sexes. Conclusions: Morning cortisol concentration, an indicator of hypothalamic–pituitary–adrenal axis activation, is prospectively associated with tobacco use in adolescents. Whether this activation indicates the cumulative effect of stressors during the life course remains to be elucidated