Walden University ScholarWorks Walden Dissertations and Doctoral Studies Walden Dissertations and Doctoral Studies Collection 2020 Traumatic Early Life Stress in the Developing Hippocampus: A Meta-Analysis of MRI Studies Sharon Johnson Walden University Follow this and additional works at: https://scholarworks.waldenu.edu/dissertations Part of the Psychology Commons This Dissertation is brought to you for free and open access by the Walden Dissertations and Doctoral Studies Collection at ScholarWorks. It has been accepted for inclusion in Walden Dissertations and Doctoral Studies by an authorized administrator of ScholarWorks. For more information, please contact [email protected]. Walden University College of Social and Behavioral Sciences This is to certify that the doctoral dissertation by Sharon Lee Johnson has been found to be complete and satisfactory in all respects, and that any and all revisions required by the review committee have been made. Review Committee Dr. Scott Wowra, Committee Chairperson, Psychology Faculty Dr. Patricia Costello, Committee Member, Psychology Faculty Dr. Kimberley Cox, University Reviewer, Psychology Faculty Chief Academic Officer and Provost Sue Subocz, Ph.D. Walden University 2020 Abstract Traumatic Early Life Stress in the Developing Hippocampus: A Meta-Analysis of MRI Studies by Sharon Lee Johnson MPhil, Walden University, 2019 M.Ed., Youngstown State University, 1994 BA, Kent State University, 1979 Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Health Psychology Walden University August 2020 Abstract Advancements in neuroimaging techniques afford researchers the opportunity to examine the actual brains of living persons, which exponentially contributes to new insights regarding brain and behavior phenomena. However, empirical studies investigating stress and the hippocampus attend primarily to adult populations - less on children and adolescents. Covariates such as the type of trauma, the duration and severity of the abuse, genetic predispositions, gender, poverty, and age often present as confounding factors that muddle the attempts to establish linkages between interpersonal, environmental, and neurobiological correlates. Although researchers primarily agree that traumatic early life stress (TELS) has some impact on early brain development, there is a lack of consensus around specific causes and the strength of influence. Tenets from Charcot's trauma theory and Selye's general adaptation syndrome organized the development of a meta-analysis which carefully examined the relationship between TELS and aberrant hippocampal development. Study selection was based on PRISMA standards, which provide a template of a 27-item qualitative checklist for the writing and reviewing of research using secondary data sources. Criteria for inclusion resulted in 22 studies identified for preliminary analysis and 9 for the final report. The analysis revealed a vast range in individual study effect sizes (d = 0.000 to -1.892). The cumulative analysis of p values ranged from p = .005 (random effects) to p < .001 (fixed effects) indicated a relationship between TELS and hippocampal development existed and underscored the necessity for researchers to shift more attention and resources to how covariates influence effect size differences. Traumatic Early Life Stress in the Developing Hippocampus: A Meta-Analysis of MRI Studies by Sharon Lee Johnson MPhil, Walden University, 2019 M.Ed., Youngstown State University, 1994 BA, Kent State University, 1979 Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Health Psychology Walden University June 2020 Dedication When I received my bachelor's degree many years ago, my father, in his confusion about the letters following my name, told everyone he knew that I was now a doctor. I vowed back then to make him honest. The effort and outcome of this dissertation are due to the unquestionable love and deep sense of pride I always felt when I looked into my father's eyes – Warren Lee Poole, Sr. Acknowledgments I am deeply grateful for the endless support of my mother, Catherine, who modeled incredible tenacity and perseverance, and for my children, each of my ten siblings, and my dearest friend whose constant cheers and check-ins gave me the strength to keep going. And to my dissertation committee members, Dr. Patricia Costello, whose constancy and presence served as an anchor, and Dr. Scott Wowra, whose gentle nudging helped me to see the light at the end of the tunnel finally. Table of Contents List of Tables................................................................................................................... v List of Figures ................................................................................................................ vi Chapter 1: Introduction to the Study ................................................................................ 1 Background ............................................................................................................... 3 Problem Statement ..................................................................................................... 4 Purpose of Study ........................................................................................................ 7 Research Question and Hypotheses ............................................................................ 7 Theoretical Framework: Trauma Theory and Selye’s Adaptation Theories ................. 8 Nature of Study ........................................................................................................ 10 Definition of Terms ................................................................................................. 11 Assumptions ............................................................................................................ 14 Scope and Delimitations .......................................................................................... 15 Limitations .............................................................................................................. 17 Significance of Study ............................................................................................... 19 Summary ................................................................................................................. 20 Chapter 2: Literature Review ......................................................................................... 22 Introduction to Literature Review ............................................................................ 22 Literature Search Strategy ........................................................................................ 23 Theoretical Framework ............................................................................................ 24 Trauma Theory .................................................................................................. 24 General Adaptation Syndrome and Local Adaptation Syndrome ........................ 29 i Contemporary Researchers ................................................................................. 31 Summary of Theoretical Foundations ................................................................. 33 Integrating Neuroscience and Psychology ................................................................ 35 The Hippocampus: Anatomy and Function ......................................................... 35 Hippocampal Dysfunction .................................................................................. 39 Primary Variables, Covariates, and Debates ............................................................. 41 Types of Traumatic Stressors ................................................................................... 42 Child Maltreatment ............................................................................................ 42 Sexual Abuse ..................................................................................................... 42 Abandonment/Orphanage/Institutionalization..................................................... 44 Emotional Neglect/Emotional Abuse.................................................................. 44 Chronic Illness of Primary Caretaker.................................................................. 45 Poverty/Low SES ............................................................................................... 45 Covariates ................................................................................................................ 46 Gender and Age ................................................................................................. 46 Duration ............................................................................................................. 48 Genetic Predisposition ....................................................................................... 50 Other Covariates ................................................................................................ 51 Magnetic Resonance Imaging .................................................................................. 52 Clinical Assessment Tools Utilized in Studies.......................................................... 53 Summary of Literature Review ................................................................................ 53 Chapter 3: Research Method .......................................................................................... 55