Smoking and psychiatric disorders: have subthreshold disorders been overlooked?
BACKGROUND
The association between smoking and mental disorders has been confirmed by several studies using cross-sectional and retrospective designs. The present study illustrates the need for differentiating subthreshold psychiatric disorders in the analysis.


METHODS
The analysis is based on cumulative ("lifetime") prevalences of mental disorders and smoking in the Zurich study. This is a longitudinal community study with a stratified sample of 591 participants and six interviews from 1979 to 1999.


RESULTS
The percentage of lifetime smokers in the Zurich study was higher both in persons with a lifetime psychiatric diagnosis (72%) and in persons with subthreshold disorders (60%) than in those without any diagnosis (40%).


CONCLUSIONS
The association between smoking and mental disorders turned out to be clearly stronger if subthreshold mental disorders were appropriately considered in the analyses. Constructing appropriate reference groups is as crucial for the analysis of mental disorders and their outcomes as constructing adequate diagnostic groups.
Research Unit for Clinical and Social Psychiatry, Psychiatric University Hospital, University of Zurich, Militärstrasse 8/PO Box 1930, 8021 CH-Zurich, Switzerland. klandolt@dgsp.uzh.ch
Karin
K
Landolt
Vladeta
V
Ajdacic-Gross
Jules
J
Angst
Kathleen R
KR
Merikangas
Alex
A
Gamma
Felix
F
Gutzwiller
Wulf
W
Rössler
D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D001523:Mental Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D015995:Prevalence; D011446:Prospective Studies; D012907:Smoking / Q000453:epidemiology* / Q000523:psychology; D013557:Switzerland / Q000453:epidemiology