Linking epigenetics and brain structure and function in depression Supervisors: Dr Heather Whalley, Dr Kathy Evans, Prof Andrew McIntosh Major Depressive Disorder (MDD) has a complex aetiology involving an intricate mix of genetic and environmental factors. Whilst the associations identified by genomewide association studies (GWAS) have yet to translate into causative variants, such studies have indicated that alterations within regulatory regions may be a frequent mechanism underlying this, and related, conditions. This implication of regulatory mechanisms fits with data from those investigating epigenetic modification, which points to differential modification of genes involved in inflammation and brain development3, 4. Structural and functional brain imaging studies have also indicated differences in brain development in the disorder. Neuroimaging studies have revealed abnormalities in cortico-striatal-limbic circuitry, consistent with altered mood regulation, anhedonia, deficits in emotion processing, motivation and reward 5. It is unclear however whether these deficits relate to underlying vulnerability to the disorder, are a secondary consequence of illness or its treatment, or indeed how they relate to epigenetic modification in the genome. So far directly the linking brain DNA methylation and expression changes with structural and functional brain imaging measures in MDD has yet to be fully exploited and is ripe for examination. The current project will specifically address the effects of DNA methylation and gene expression in MDD on brain structure and function. The successful applicant will analyse fMRI data and integrate this with DNA methylation and gene expression data providing new insights into the connections between these currently relatively disparate areas. This proposal brings together two complimentary groups from different disciplines, being conducted jointly between the Division of Psychiatry and the Institute of Genetics and Molecular Medicine in Edinburgh. Together the applicants have expertise in all areas of the proposal. This project will be of particular interest to students with a neuroscience, and/or genetics background. 1. 2. 3. 4. 5. Lopez-Leon, S. et al. Meta-analyses of genetic studies on major depressive disorder. Mol. Psychiatry 13, 772-785 (2008). Bosker, F.J. et al. Poor replication of candidate genes for major depressive disorder using genome-wide association data. Mol. Psychiatry 16, 516-532 (2011). Uddin, M. et al. Epigenetic and inflammatory marker profiles associated with depression in a community-based epidemiologic sample. Psychol. Med. 41, 997-1007 (2011). Sabunciyan, S. et al. Genome-wide DNA methylation scan in major depressive disorder. PLoS One 7, e34451 (2012). Phillips, M.L., Drevets, W.C., Rauch, S.L. & Lane, R. Neurobiology of emotion perception II: Implications for major psychiatric disorders. Biol. Psychiatry 54, 515-528 (2003).