Cardiff University | Prifysgol Caerdydd ORCA
Online Research @ Cardiff 
WelshClear Cookie - decide language by browser settings

Smoking and the risk for bipolar disorder: evidence from a bidirectional Mendelian randomisation study

Vermeulen, Jentien M., Wootton, Robyn E., Treur, Jorien L., Sallis, Hannah M., Jones, Hannah J., Zammit, Stanley, van den Brink, Wim, Goodwin, Guy M., de Haan, Lieuwe and Munafò, Marcus R. 2021. Smoking and the risk for bipolar disorder: evidence from a bidirectional Mendelian randomisation study. British Journal of Psychiatry 218 (2) , pp. 88-94. 10.1192/bjp.2019.202

[thumbnail of Smoking and the risk for bipolar disorder.pdf]
PDF - Accepted Post-Print Version
Download (213kB) | Preview


Background There is increasing evidence that smoking is a risk factor for severe mental illness, including bipolar disorder. Conversely, patients with bipolar disorder might smoke more (often) as a result of the psychiatric disorder. Aims We conducted a bidirectional Mendelian randomisation (MR) study to investigate the direction and evidence for a causal nature of the relationship between smoking and bipolar disorder. Method We used publicly available summary statistics from genome-wide association studies on bipolar disorder, smoking initiation, smoking heaviness, smoking cessation and lifetime smoking (i.e. a compound measure of heaviness, duration and cessation). We applied analytical methods with different, orthogonal assumptions to triangulate results, including inverse-variance weighted (IVW), MR-Egger, MR-Egger SIMEX, weighted-median, weighted-mode and Steiger-filtered analyses. Results Across different methods of MR, consistent evidence was found for a positive effect of smoking on the odds of bipolar disorder (smoking initiation ORIVW = 1.46, 95% CI 1.28–1.66, P = 1.44 × 10−8, lifetime smoking ORIVW = 1.72, 95% CI 1.29–2.28, P = 1.8 × 10−4). The MR analyses of the effect of liability to bipolar disorder on smoking provided no clear evidence of a strong causal effect (smoking heaviness betaIVW = 0.028, 95% CI 0.003–0.053, P = 2.9 × 10−2). Conclusions These findings suggest that smoking initiation and lifetime smoking are likely to be a causal risk factor for developing bipolar disorder. We found some evidence that liability to bipolar disorder increased smoking heaviness. Given that smoking is a modifiable risk factor, these findings further support investment into smoking prevention and treatment in order to reduce mental health problems in future generations.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Medicine
MRC Centre for Neuropsychiatric Genetics and Genomics (CNGG)
Publisher: Cambridge University Press (CUP)
ISSN: 0007-1250
Date of First Compliant Deposit: 15 October 2019
Date of Acceptance: 14 August 2019
Last Modified: 10 Feb 2021 04:08

Citation Data

Cited 18 times in Scopus. View in Scopus. Powered By Scopus® Data

Actions (repository staff only)

Edit Item Edit Item


Downloads per month over past year

View more statistics