PT  - JOURNAL ARTICLE
AU  - Amy E Taylor
AU  - Meg E Fluharty
AU  - Johan H Bjørngaard
AU  - Maiken Elvestad Gabrielsen
AU  - Frank Skorpen
AU  - Riccardo E Marioni
AU  - Archie Campbell
AU  - Jorgen Engmann
AU  - Saira Saeed Mirza
AU  - Anu Loukola
AU  - Tiina Laatikainen
AU  - Timo Partonen
AU  - Marika Kaakinen
AU  - Francesca Ducci
AU  - Alana Cavadino
AU  - Lise Lotte N Husemoen
AU  - Tarunveer Singh Ahluwalia
AU  - Rikke Kart Jacobsen
AU  - Tea Skaaby
AU  - Jeanette Frost Ebstrup
AU  - Erik Lykke Mortensen
AU  - Camelia C Minica
AU  - Jacqueline M Vink
AU  - Gonneke Willemsen
AU  - Pedro Marques-Vidal
AU  - Caroline E Dale
AU  - Antoinette Amuzu
AU  - Lucy T Lennon
AU  - Jari Lahti
AU  - Aarno Palotie
AU  - Katri Räikkönen
AU  - Andrew Wong
AU  - Lavinia Paternoster
AU  - Angelita Pui-Yee Wong
AU  - L John Horwood
AU  - Michael Murphy
AU  - Elaine C Johnstone
AU  - Martin A Kennedy
AU  - Zdenka Pausova
AU  - Tomáš Paus
AU  - Yoav Ben-Shlomo
AU  - Ellen A Nohr
AU  - Diana Kuh
AU  - Mika Kivimaki
AU  - Johan G Eriksson
AU  - Richard W Morris
AU  - Juan P Casas
AU  - Martin Preisig
AU  - Dorret I Boomsma
AU  - Allan Linneberg
AU  - Chris Power
AU  - Elina Hyppönen
AU  - Juha Veijola
AU  - Marjo-Riitta Jarvelin
AU  - Tellervo Korhonen
AU  - Henning Tiemeier
AU  - Meena Kumari
AU  - David J Porteous
AU  - Caroline Hayward
AU  - Pål R Romundstad
AU  - George Davey Smith
AU  - Marcus R Munafò
TI  - Investigating the possible causal association of smoking with depression and anxiety using Mendelian randomisation meta-analysis: the CARTA consortium
AID  - 10.1136/bmjopen-2014-006141
DP  - 2014 Oct 01
TA  - BMJ Open
PG  - e006141
VI  - 4
IP  - 10
4099  - http://bmjopen.bmj.com/content/4/10/e006141.short
4100  - http://bmjopen.bmj.com/content/4/10/e006141.full
SO  - BMJ Open2014 Oct 01; 4
AB  - Objectives To investigate whether associations of smoking with depression and anxiety are likely to be causal, using a Mendelian randomisation approach. Design Mendelian randomisation meta-analyses using a genetic variant (rs16969968/rs1051730) as a proxy for smoking heaviness, and observational meta-analyses of the associations of smoking status and smoking heaviness with depression, anxiety and psychological distress. Participants Current, former and never smokers of European ancestry aged ≥16 years from 25 studies in the Consortium for Causal Analysis Research in Tobacco and Alcohol (CARTA). Primary outcome measures Binary definitions of depression, anxiety and psychological distress assessed by clinical interview, symptom scales or self-reported recall of clinician diagnosis. Results The analytic sample included up to 58 176 never smokers, 37 428 former smokers and 32 028 current smokers (total N=127 632). In observational analyses, current smokers had 1.85 times greater odds of depression (95% CI 1.65 to 2.07), 1.71 times greater odds of anxiety (95% CI 1.54 to 1.90) and 1.69 times greater odds of psychological distress (95% CI 1.56 to 1.83) than never smokers. Former smokers also had greater odds of depression, anxiety and psychological distress than never smokers. There was evidence for positive associations of smoking heaviness with depression, anxiety and psychological distress (ORs per cigarette per day: 1.03 (95% CI 1.02 to 1.04), 1.03 (95% CI 1.02 to 1.04) and 1.02 (95% CI 1.02 to 1.03) respectively). In Mendelian randomisation analyses, there was no strong evidence that the minor allele of rs16969968/rs1051730 was associated with depression (OR=1.00, 95% CI 0.95 to 1.05), anxiety (OR=1.02, 95% CI 0.97 to 1.07) or psychological distress (OR=1.02, 95% CI 0.98 to 1.06) in current smokers. Results were similar for former smokers. Conclusions Findings from Mendelian randomisation analyses do not support a causal role of smoking heaviness in the development of depression and anxiety.