Aims To examine the strength of association between smoking and mood disorders and the association between smoking and its traditional risk factors, comparing those who started smoking in adolescence with those who started smoking in early adulthood.
Design and participants The analyses relied on prospective data from the Zurich Study. This longitudinal community study started in 1979 with a stratified sample of 591 participants aged 20/21 years, weighted towards those with mental disorders. Follow-up interviews were conducted at ages 23, 28, 30, 35 and 41.
Measurements In this analysis the adult versus adolescent onset of smoking was regressed on the cumulative prevalence of mood disorders, personality characteristics measured by the Freiburg Personality Inventory, common risk factors such as parental smoking, conduct and school problems, troubles with the family and basic socio-demographic variables (sex, education).
Findings In the Zurich Study cohort we found that 61.6% were former or current smokers, of whom 87% started smoking before the age of 20 and 13% after the age of 20. Adolescent onset of smoking was associated strongly with later major depression, dysthymia or bipolar disorders and, furthermore, with parental smoking, extroverted personality and discipline problems and rebelliousness in youth. However, only depression and dysthymia were associated with adult onset smoking and other risk factors associated with smoking were not so associated in this group.
Conclusions Correlates of smoking onset in adolescence are mainly not applicable to the onset of smoking in young adulthood. Smoking onset beyond adolescence is an open research issue.