title: Challenges and novel approaches for investigating molecular mediation.
abstract: Understanding mediation is useful for identifying intermediates lying between an exposure and an outcome which, when intervened upon, will block (some or all of) the causal pathway between the exposure and outcome. Mediation approaches used in conventional epidemiology have been adapted to understanding the role of molecular intermediates in situations of high-dimensional omics data with varying degrees of success. In particular, the limitations of observational epidemiological study including confounding, reverse causation and measurement error can afflict conventional mediation approaches and may lead to incorrect conclusions regarding causal effects. Solutions to analysing mediation which overcome these problems include the use of instrumental variable methods such as Mendelian randomization, which may be applied to evaluate causality in increasingly complex networks of omics data.
authors.affiliation: MRC Integrative Epidemiology Unit, University of Bristol, UK School of Social and Community Medicine, University of Bristol, UK.
authors.forename: R C
authors.initials: RC
authors.lastname: Richmond
authors.affiliation: MRC Integrative Epidemiology Unit, University of Bristol, UK School of Social and Community Medicine, University of Bristol, UK.
authors.forename: G
authors.initials: G
authors.lastname: Hemani
authors.affiliation: MRC Integrative Epidemiology Unit, University of Bristol, UK School of Social and Community Medicine, University of Bristol, UK.
authors.forename: K
authors.initials: K
authors.lastname: Tilling
authors.affiliation: MRC Integrative Epidemiology Unit, University of Bristol, UK School of Social and Community Medicine, University of Bristol, UK.
authors.forename: G
authors.initials: G
authors.lastname: Davey Smith
authors.affiliation: MRC Integrative Epidemiology Unit, University of Bristol, UK School of Social and Community Medicine, University of Bristol, UK caroline.relton@bristol.ac.uk.
authors.forename: C L
authors.initials: CL
authors.lastname: Relton