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dc.contributor.authorSchumann, Lyndallen
dc.date2016-10-04 11:55:23.198
dc.date2016-10-04 17:37:07.888
dc.date.accessioned2016-10-05T14:39:17Z
dc.date.issued2016-10-05
dc.identifier.urihttp://hdl.handle.net/1974/15069
dc.descriptionThesis (Ph.D, Psychology) -- Queen's University, 2016-10-04 17:37:07.888en
dc.description.abstractGenetic and environmental factors interact to influence vulnerability for internalizing psychopathology, including Major Depressive Disorder (MDD). The mechanisms that account for how environmental stress can alter biological systems are not yet well understood yet are critical to develop more accurate models of vulnerability and targeted interventions. Epigenetic influences, and more specifically, DNA methylation, may provide a mechanism by which stress could program gene expression, thereby altering key systems implicated in depression, such as frontal-limbic circuitry and its critical role in emotion regulation. This thesis investigated the role of environmental factors from infancy and throughout the lifespan affecting the serotonergic (5-HT) system in the vulnerability to and treatment of depression and anxiety and potential underlying DNA methylation processes. First, we investigated the contributions of additive genetic vs. environmental factors on an early trait phenotype for depression (negative emotionality) in infants and their stability over time in the first 2 years of life. We provided evidence of the substantial contributions of both genetic and shared environmental factors to this trait, as well as genetically- and environmentally- mediated stability and innovation. Second, we studied how childhood environmental stress is associated with peripheral DNA methylation of the serotonin transporter gene, SLC6A4, as well as long-term trajectories of internalizing behaviours. There was a relationship between childhood psychosocial adversity and SLC6A4 methylation in males, as well as between SLC6A4 methylation and internalizing trajectory in both sexes. Third, we investigated changes in emotion processing and epigenetic modification of the SLC6A4 gene in depressed adolescents before and after Mindfulness-Based Cognitive Therapy (MBCT). The alterations from pre- to post-treatment in connectivity between the ACC and other network regions and SLC6A4 methylation suggested that MBCT may work to optimize the connectivity of brain networks involved in cognitive control of emotion as well as also normalize the relationship between SLC6A4 methylation and activation patterns in frontal-limbic circuitry. Our results from these three studies strengthen the theory that environmental influences are critical in establishing early vulnerability factors for MDD, driving epigenetic processes, and altering brain processes as an individual undergoes treatment, or experiences relapse.en
dc.language.isoengen
dc.relation.ispartofseriesCanadian thesesen
dc.rightsQueen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canadaen
dc.rightsProQuest PhD and Master's Theses International Dissemination Agreementen
dc.rightsIntellectual Property Guidelines at Queen's Universityen
dc.rightsCopying and Preserving Your Thesisen
dc.rightsThis publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.en
dc.rightsThis publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.en
dc.subjectEpigeneticsen
dc.subjectDepressionen
dc.subjectDNA Methylationen
dc.subjectNeurodevelopmetal Modelen
dc.titleEnivronmental Influences and Epigenetic Mechanisms in Risk for Depressionen
dc.typethesisen
dc.description.restricted-thesisMy supervisor Dr. Booij and I have agreed to restrict this thesis from publication for 1 year since we want to attempt to submit to academic journalsen
dc.description.degreePhDen
dc.contributor.supervisorBooij, Lindaen
dc.contributor.departmentPsychologyen
dc.embargo.terms1825en
dc.embargo.liftdate2021-10-04
dc.degree.grantorQueen's University at Kingstonen


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