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The effects of tobacco smoking on age of onset of psychosis and psychotic symptoms in a first episode psychosis population

Research output: Contribution to journalArticlepeer-review

Lauren M. Hickling, Victor Ortiz-Garcia de la Foz, Rosa Ayesa-Arriola, Benedicto Crespo-Facorro, Philip McGuire, Rocio Perez-Iglesias

Original languageEnglish
Pages (from-to)526-532
Issue number3
Early online date13 Dec 2016
Accepted/In press23 Sep 2016
E-pub ahead of print13 Dec 2016
PublishedMar 2017


King's Authors


Background and Aims Research suggests that tobacco smokers may develop psychosis at an earlier age than non-smokers, with effects on psychotic symptoms. We aimed to test the difference in age of onset of psychosis between smokers and non-smokers . Design Self-report data was collected from smokers and non-smokers in a population of first episode psychosis patients. Setting
Outpatient first episode psychosis programme in Santander (Cantabria), Spain. Participants Three hundred and ninety seven patients (226 male, 171 female) who agreed to take part between 2001and 2011. Measurements Age of onset of psychosis, age of smoking initiation, demographics,family history of psychosis, and cannabis use were collected by self-report. Findings Kaplan-Meier analysis showed that smokers had a significantly lower mean age of psychosis onset (smokers=27.4 (±8.1) years, non-smokers=30.5 (±9.9) years) than non-smokers (χ²(1)=11.72, p=0.001). The Cox Proportional Hazard’s Model showed no significant difference in the age of psychosis onset between smokers and non-smokers adjusted for covariates (hazard ratio (HR)=1.034,95% Confidence interval (CI) 0.828-1.291). Age of psychosis onset was significantly predicted by
cannabis use (HR=2.073, 95% CI 1.633-2.633) and gender (HR=1.706,95% CI 1.363-2.135).
Conclusions Smokers do not appear to have a significantly earlier age of psychosis onset than nonsmokers after taking into account cannabis use and gender.

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