The relationship between smoking status and cortisol secretion.
BACKGROUND
Evidence for an association of smoking status with cortisol secretion is mixed.


OBJECTIVE
The objective of the study was to assess the relationship between smoking status and salivary cortisol.


METHODS
This was a cross-sectional study of smoking status and cortisol secretion from phase 7 (2002-2004) of the Whitehall II study.


METHODS
An occupational cohort was originally recruited in 1985-1987.


METHODS
The study population consisted of 3103 men (1514 never-smokers, 1278 ex-smokers, and 311 smokers) and 1128 women (674 never-smokers, 347 ex-smokers, and 107 smokers). Information was collected on smoking status, average number of cigarettes smoked, and additional covariates.


METHODS
Saliva samples were taken on waking; waking + 0.5, 2.5, 8, and 12 h; and bedtime for the assessment of cortisol.


RESULTS
Smoking status was significantly associated with increased salivary cortisol release throughout the day (P < 0.001) adjusted for covariates; this was apparent for the cortisol awakening response (P < 0.001) when examined separately. Compared with never-smokers, smokers had higher release of total cortisol (P = 0.002), whereas no difference was observed between never-smokers and ex-smokers (P = 0.594): mean release per hour (nanomoles per liter), never-smokers, 4.13 [confidence interval (CI) 4.02-4.24]; ex-smokers, 4.21 (CI 4.08-4.35); smokers, 4.63 (CI 4.35-4.93). There was no significant relationship between number of cigarettes smoked and total cortisol release. However, a difference was observed for the cortisol awakening response: mean release by tertiles of cigarettes smoked (nanomoles per liter): high, 13.49 (CI 10.74-16.23); medium, 9.58 (CI 7.40-11.76); low, 8.49 (CI 5.99-10.99), P = 0.029.


CONCLUSIONS
Salivary cortisol is increased in current smokers, compared with nonsmokers; no differences were observed between ex-smokers and never-smokers, suggesting that smoking has a short-term effect on the neuroendocrine system.
Badrick
Ellena
E
Department of Epidemiology and Public Health, University College London, London WC1E 6BT, United Kingdom. e.badrick@ucl.ac.uk
Kirschbaum
Clemens
C
Kumari
Meena
M
D015331:Cohort Studies; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D012463:Saliva / Q000737:chemistry*; D012907:Smoking / Q000378:metabolism*; D016540:Smoking Cessation
D006854:Hydrocortisone