Hypothalamic–pituitary–adrenal axis and smoking and drinking onset among adolescents: the longitudinal cohort TRacking Adolescents' Individual Lives Survey (TRAILS)

Aims  We examined within a prospective longitudinal study whether cortisol levels were associated with smoking or drinking behaviours, taking parental substance use into account. Design  The influence of parental substance use on cortisol levels of their adolescent offspring at age 10–12 years was examined. Next, cortisol levels of adolescents who initiated smoking or drinking at the first data collection (age 10–12) were compared to non‐users. Finally, we examined whether cortisol levels could predict new onset and frequency of smoking and drinking 2 years later. Setting and participants  First and second assessment data of the TRacking Adolescents' Individual Lives Survey (TRAILS) were used, including 1768 Dutch adolescents aged 10–12 years, who were followed‐up across a period of 2 years. Measurements  Cortisol was measured in saliva samples at awakening, 30 minutes later, and at 8 p.m. at age 10–12. Self‐reported substance use at age 10–12 and 13–14, and parental self‐reported substance use were used. Findings  Only maternal substance use was related to slightly lower adolescent cortisol levels at 8 p.m. Both maternal and paternal substance use were associated with adolescent smoking and drinking at age 13–14, although fathers' use only predicted the amount used and not the chance of ever use. Finally, higher cortisol levels were related moderately to current smoking and future frequency of smoking, but not to alcohol use. Conclusions  In a general population, parental heavy substance use does not seem to affect cortisol levels consistently in their offspring. We found some evidence for higher, instead of lower, hypothalamic–pituitary–adrenal axis activity as a predictor of smoking in early adolescence.