University of Oulu

Scott JG, Matuschka L, Niemelä S, Miettunen J, Emmerson B and Mustonen A (2018) Evidence of a Causal Relationship Between Smoking Tobacco and Schizophrenia Spectrum Disorders. Front. Psychiatry 9:607. doi: 10.3389/fpsyt.2018.00607

Evidence of a causal relationship between smoking tobacco and schizophrenia spectrum disorders

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Author: Scott, James G.1,2,3; Matuschka, Lori1,2; Niemelä, Solja4,5;
Organizations: 1Faculty of Medicine, The University of Queensland, Herston, QLD, Australia
2Queensland Centre for Mental Health Research, Wacol, QLD, Australia
3Metro North Mental Health, Royal Brisbane and Women’s Hospital, Herston, QLD, Australia
4Faculty of Medicine, University of Turku, Turku, Finland
5Department of Psychiatry, South-Western Hospital District, Turku, Finland
6Center for Life Course Health Research, University of Oulu, Oulu, Finland
7Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.2 MB)
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Language: English
Published: Frontiers Media, 2018
Publish Date: 2019-02-21


There has been emerging evidence of an association between tobacco smoking and schizophrenia spectrum disorders (SSD). Two meta-analyses have reported that people who smoke tobacco have an ~2-fold increased risk of incident schizophrenia or psychosis, even after adjusting for confounding factors. This study aimed to critically appraise the research which has examined the association between tobacco smoking and SSD against the Bradford Hill criteria for causality, to determine the strength of the evidence for a causal relationship. Eight longitudinal studies (seven cohort studies and one case control study) were identified which examined tobacco smoking as an exposure and psychosis as an outcome. All seven cohort studies were assessed as being of high quality using the Newcastle-Ottawa Scale. Six of the eight studies found a statistically significant positive association between tobacco smoking and onset of SSD. These studies reported a consistent association with a moderate to large effect size and a dose response relationship. The studies adjusted for multiple potential confounders including age, sex, socioeconomic status, shared genetic risk, prodromal symptoms, and comorbid cannabis and other substance use. The studies did not adjust for exposure to childhood trauma or prenatal tobacco. There was substantial though inconclusive evidence supporting a causal relationship between tobacco smoking and increased risk of SSD. If a causal relationship does exist, nicotine is most likely responsible for this association. This raises serious public health concerns about the increasing use of e-cigarettes and other products, particularly by adolescents whose nicotine use may increase their risk of SSD. Research is urgently needed to examine the association between e-cigarette use and incident psychosis, particularly in adolescents and young adults.

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Series: Frontiers in psychiatry
ISSN: 1664-0640
ISSN-E: 1664-0640
ISSN-L: 1664-0640
Volume: 9
Article number: 607
DOI: 10.3389/fpsyt.2018.00607
Type of Publication: A2 Review article in a scientific journal
Field of Science: 3124 Neurology and psychiatry
Funding: JS is supported by a National Health and Medical Research Council Practitioner Fellowship Grant APP1105807 and employed by The Queensland Centre for Mental Health Research which receives core funding from the Queensland Health. AM is supported by Juho Vainio Foundation, Scholarship Fund of the University of Oulu, Oulun Lääketieteellinen tutkimussäätiö and The Hospital District of South Ostrobothnia, Finland. JM is supported by Academy of Finland (#268336).
Academy of Finland Grant Number: 268336
Detailed Information: 268336 (Academy of Finland Funding decision)
Copyright information: Copyright © 2018 Scott, Matuschka, Niemelä, Miettunen, Emmerson and Mustonen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.