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Chen J, Chen R, Xiang S, Li N, Gao C, Wu C, Zhang Q, Zhao Y, Liao Y, Stewart R, Xu Y, Shi Y, Li Z. Cigarette smoking and schizophrenia: Mendelian randomisation study. Br J Psychiatry 2021; 218:98-103. [PMID: 32552923 DOI: 10.1192/bjp.2020.116] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND The link between schizophrenia and cigarette smoking has been well established through observational studies. However, the cause-effect relationship remains unclear. AIMS We conducted Mendelian randomisation analyses to assess any causal relationship between genetic variants related to four smoking-related traits and the risk of schizophrenia. METHOD We performed a two-sample Mendelian randomisation using summary statistics from genome-wide association studies (GWAS) of smoking-related traits and schizophrenia (7711 cases, 18 327 controls) in East Asian populations. Single nucleotide polymorphisms (SNPs) correlated with smoking behaviours (smoking initiation, smoking cessation, age at smoking initiation and quantity of smoking) were investigated in relation to schizophrenia using the inverse-variance weighted (IVW) method. Further sensitivity analyses, including Mendelian randomisation-Egger (MR-Egger), weighted median estimates and leave-one-out analysis, were used to test the consistency of the results. RESULTS The associated SNPs for the four smoking behaviours were not significantly associated with schizophrenia status. Pleiotropy did not inappropriately affect the results. CONCLUSIONS Cigarette smoking is a complex behaviour in people with schizophrenia. Understanding factors underlying the observed association remains important; however, our findings do not support a causal role of smoking in influencing risk of schizophrenia.
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Affiliation(s)
- Jianhua Chen
- Affiliated Hospital of Qingdao University & Biomedical Sciences Institute of Qingdao University, Qingdao University; and Shanghai Clinical Research Centre for Mental Health, Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Centre, Shanghai Jiao Tong University School of Medicine; and Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Collaborative Innovation Centre for Brain Science, Shanghai Jiao Tong University, P. R. China; and Department of Psychological Medicine, Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Ruirui Chen
- Affiliated Hospital of Qingdao University & Biomedical Sciences Institute of Qingdao University, Qingdao University, P. R. China
| | - Siying Xiang
- Shanghai Clinical Research Centre for Mental Health, Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Centre, Shanghai Jiao Tong University School of Medicine, P. R. China
| | - Ningning Li
- Shanghai Clinical Research Centre for Mental Health, Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Centre, Shanghai Jiao Tong University School of Medicine, P. R. China
| | - Chengwen Gao
- Affiliated Hospital of Qingdao University & Biomedical Sciences Institute of Qingdao University, Qingdao University, P. R. China
| | - Chuanhong Wu
- Affiliated Hospital of Qingdao University & Biomedical Sciences Institute of Qingdao University, Qingdao University, P. R. China
| | - Qian Zhang
- Affiliated Hospital of Qingdao University & Biomedical Sciences Institute of Qingdao University, Qingdao University, P. R. China
| | - Yalin Zhao
- Affiliated Hospital of Qingdao University & Biomedical Sciences Institute of Qingdao University, Qingdao University, P. R. China
| | - Yanhui Liao
- Department of Psychiatry, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, P. R. China
| | - Robert Stewart
- Department of Psychological Medicine, Institute of Psychiatry, Psychology and Neuroscience, King's College London; and South London and Maudsley NHS Foundation Trust, London, UK
| | - Yifeng Xu
- Shanghai Clinical Research Centre for Mental Health, Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Centre, Shanghai Jiao Tong University School of Medicine, P. R. China
| | - Yongyong Shi
- Affiliated Hospital of Qingdao University & Biomedical Sciences Institute of Qingdao University, Qingdao University; and Shanghai Clinical Research Centre for Mental Health, Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Centre, Shanghai Jiao Tong University School of Medicine; and Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Collaborative Innovation Centre for Brain Science, Shanghai Jiao Tong University; and Shanghai Key Laboratory of Sleep Disordered Breathing; and Shanghai Changning Mental Health Centre; and Department of Psychiatry, First Teaching Hospital of Xinjiang Medical University, Urumqi, P. R. China
| | - Zhiqiang Li
- Affiliated Hospital of Qingdao University & Biomedical Sciences Institute of Qingdao University, Qingdao University; and Shanghai Clinical Research Centre for Mental Health, Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Centre, Shanghai Jiao Tong University School of Medicine; and Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Collaborative Innovation Centre for Brain Science, Shanghai Jiao Tong University; and Shanghai Key Laboratory of Sleep Disordered Breathing, P. R. China
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