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Effect of smoking on physical and cognitive capability in later life: a multicohort study using observational and genetic approaches

OBJECTIVES: The observed associations between smoking and functional measures at older ages are vulnerable to bias and confounding. Mendelian randomisation (MR) uses genotype as an instrumental variable to estimate unconfounded causal associations. We conducted a meta-analysis of the observational a...

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Autores principales: North, Teri-Louise, Palmer, Tom M, Lewis, Sarah J, Cooper, Rachel, Power, Chris, Pattie, Alison, Starr, John M, Deary, Ian J, Martin, Richard M, Aihie Sayer, Avan, Kumari, Meena, Cooper, Cyrus, Kivimaki, Mika, Kuh, Diana, Ben-Shlomo, Yoav, Day, Ian N M
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BMJ Publishing Group 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4679991/
https://www.ncbi.nlm.nih.gov/pubmed/26671949
http://dx.doi.org/10.1136/bmjopen-2015-008393
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author North, Teri-Louise
Palmer, Tom M
Lewis, Sarah J
Cooper, Rachel
Power, Chris
Pattie, Alison
Starr, John M
Deary, Ian J
Martin, Richard M
Aihie Sayer, Avan
Kumari, Meena
Cooper, Cyrus
Kivimaki, Mika
Kuh, Diana
Ben-Shlomo, Yoav
Day, Ian N M
author_facet North, Teri-Louise
Palmer, Tom M
Lewis, Sarah J
Cooper, Rachel
Power, Chris
Pattie, Alison
Starr, John M
Deary, Ian J
Martin, Richard M
Aihie Sayer, Avan
Kumari, Meena
Cooper, Cyrus
Kivimaki, Mika
Kuh, Diana
Ben-Shlomo, Yoav
Day, Ian N M
author_sort North, Teri-Louise
collection PubMed
description OBJECTIVES: The observed associations between smoking and functional measures at older ages are vulnerable to bias and confounding. Mendelian randomisation (MR) uses genotype as an instrumental variable to estimate unconfounded causal associations. We conducted a meta-analysis of the observational associations and implemented an MR approach using the smoking-related single nucleotide polymorphism rs16969968 to explore their causal nature. SETTING: 9 British cohorts belonging to the HALCyon collaboration. PARTICIPANTS: Individual participant data on N=26 692 individuals of European ancestry (N from earliest phase analysed per study) of mean ages 50–79 years were available for inclusion in observational meta-analyses of the primary outcomes. PRIMARY OUTCOMES: Physical capability, cognitive capability and cognitive decline. The smoking exposures were cigarettes per day, current versus ex-smoker, current versus never smoker and ever versus never smoker. RESULTS: In observational analyses current and ever smoking were generally associated with poorer physical and cognitive capability. For example, current smokers had a general fluid cognition score which was 0.17 z-score units (95% CI −0.221 to −0.124) lower than ex-smokers in cross-sectional analyses. Current smokers had a walk speed which was 0.25 z-score units lower than never smokers (95% CI −0.338 to −0.170). An MR instrumental variable approach for current versus ex-smoker and number of cigarettes smoked per day produced CIs which neither confirmed nor refuted the observational estimates. The number of genetic associations stratified by smoking status were consistent with type I error. CONCLUSIONS: Our observational analysis supports the hypothesis that smoking is detrimental to physical and cognitive capability. Further studies are needed for a suitably powered MR approach.
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spelling pubmed-46799912015-12-22 Effect of smoking on physical and cognitive capability in later life: a multicohort study using observational and genetic approaches North, Teri-Louise Palmer, Tom M Lewis, Sarah J Cooper, Rachel Power, Chris Pattie, Alison Starr, John M Deary, Ian J Martin, Richard M Aihie Sayer, Avan Kumari, Meena Cooper, Cyrus Kivimaki, Mika Kuh, Diana Ben-Shlomo, Yoav Day, Ian N M BMJ Open Smoking and Tobacco OBJECTIVES: The observed associations between smoking and functional measures at older ages are vulnerable to bias and confounding. Mendelian randomisation (MR) uses genotype as an instrumental variable to estimate unconfounded causal associations. We conducted a meta-analysis of the observational associations and implemented an MR approach using the smoking-related single nucleotide polymorphism rs16969968 to explore their causal nature. SETTING: 9 British cohorts belonging to the HALCyon collaboration. PARTICIPANTS: Individual participant data on N=26 692 individuals of European ancestry (N from earliest phase analysed per study) of mean ages 50–79 years were available for inclusion in observational meta-analyses of the primary outcomes. PRIMARY OUTCOMES: Physical capability, cognitive capability and cognitive decline. The smoking exposures were cigarettes per day, current versus ex-smoker, current versus never smoker and ever versus never smoker. RESULTS: In observational analyses current and ever smoking were generally associated with poorer physical and cognitive capability. For example, current smokers had a general fluid cognition score which was 0.17 z-score units (95% CI −0.221 to −0.124) lower than ex-smokers in cross-sectional analyses. Current smokers had a walk speed which was 0.25 z-score units lower than never smokers (95% CI −0.338 to −0.170). An MR instrumental variable approach for current versus ex-smoker and number of cigarettes smoked per day produced CIs which neither confirmed nor refuted the observational estimates. The number of genetic associations stratified by smoking status were consistent with type I error. CONCLUSIONS: Our observational analysis supports the hypothesis that smoking is detrimental to physical and cognitive capability. Further studies are needed for a suitably powered MR approach. BMJ Publishing Group 2015-12-15 /pmc/articles/PMC4679991/ /pubmed/26671949 http://dx.doi.org/10.1136/bmjopen-2015-008393 Text en Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/ This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See: http://creativecommons.org/licenses/by/4.0/
spellingShingle Smoking and Tobacco
North, Teri-Louise
Palmer, Tom M
Lewis, Sarah J
Cooper, Rachel
Power, Chris
Pattie, Alison
Starr, John M
Deary, Ian J
Martin, Richard M
Aihie Sayer, Avan
Kumari, Meena
Cooper, Cyrus
Kivimaki, Mika
Kuh, Diana
Ben-Shlomo, Yoav
Day, Ian N M
Effect of smoking on physical and cognitive capability in later life: a multicohort study using observational and genetic approaches
title Effect of smoking on physical and cognitive capability in later life: a multicohort study using observational and genetic approaches
title_full Effect of smoking on physical and cognitive capability in later life: a multicohort study using observational and genetic approaches
title_fullStr Effect of smoking on physical and cognitive capability in later life: a multicohort study using observational and genetic approaches
title_full_unstemmed Effect of smoking on physical and cognitive capability in later life: a multicohort study using observational and genetic approaches
title_short Effect of smoking on physical and cognitive capability in later life: a multicohort study using observational and genetic approaches
title_sort effect of smoking on physical and cognitive capability in later life: a multicohort study using observational and genetic approaches
topic Smoking and Tobacco
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4679991/
https://www.ncbi.nlm.nih.gov/pubmed/26671949
http://dx.doi.org/10.1136/bmjopen-2015-008393
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