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An Integrative Chronobiological-Cognitive Approach to Seasonal Affective Disorder Jennifer Nicole Rough University of Vermont

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An Integrative Chronobiological-Cognitive Approach to Seasonal Affective Disorder Jennifer Nicole Rough University of Vermont University of Vermont ScholarWorks @ UVM Graduate College Dissertations and Theses Dissertations and Theses 2016 An integrative chronobiological-cognitive approach to seasonal affective disorder Jennifer Nicole Rough University of Vermont Follow this and additional works at: https://scholarworks.uvm.edu/graddis Part of the Clinical Psychology Commons Recommended Citation Rough, Jennifer Nicole, "An integrative chronobiological-cognitive approach to seasonal affective disorder" (2016). Graduate College Dissertations and Theses. 483. https://scholarworks.uvm.edu/graddis/483 This Dissertation is brought to you for free and open access by the Dissertations and Theses at ScholarWorks @ UVM. It has been accepted for inclusion in Graduate College Dissertations and Theses by an authorized administrator of ScholarWorks @ UVM. For more information, please contact [email protected]. AN INTEGRATIVE CHRONOBIOLOGICAL-COGNITIVE APPROACH TO SEASONAL AFFECTIVE DISORDER A Dissertation Presented by Jennifer Nicole Rough to the Faculty of the Graduate College of the University of Vermont In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Specializing in Clinical Psychology January, 2016 Defense Date: September, 17, 2015 Dissertation Examination Committee: Kelly Rohan, Ph.D., Advisor Terry Rabinowitz, M.D., Chairperson Timothy Stickle, Ph.D. Mark Bouton, Ph.D. Donna Toufexis, Ph.D. Cynthia J. Forehand, Ph.D., Dean of the Graduate College ABSTRACT Seasonal affective disorder (SAD) is characterized by annual recurrence of clinical depression in the fall and winter months. The importance of SAD as a public health problem is underscored by its high prevalence (an estimated 5%) and by the large amount of time individuals with SAD are impaired (on average, 5 months each year). The specific cause of SAD remains unknown; however, researchers have identified possible chronobiological and psychological vulnerabilities to SAD. The study aimed to clarify psychological and chronobiological correlates of SAD in the first test of an integrative model of SAD. The project used a longitudinal design to test the respective contributions of the chronobiological and cognitive vulnerabilities on winter depression severity in 31 SAD patients and 33 never-depressed controls at sites in Burlington, VT and Pittsburgh, PA. The measures selected for the cognitive vulnerability were established measures of vulnerability to nonseasonal depression with empirical support for their relevance to SAD: brooding rumination, dysfunctional attitudes, cognitive reactivity to an induced sad mood, and season-specific cognitions. The chronobiological vulnerability was measured as Phase Angle Difference (PAD) and deviation from PAD of 6 hours. All measures were completed once in the summer, when the SAD patients were remitted, and once in the winter, when patients were clinically depressed. Patients were distinguished from controls on most cognitive vulnerability measures (brooding, as well as rumination, dysfunctional attitudes, and seasonal beliefs). SAD patients exhibited shorter PAD than controls, but did not exhibit greater deviation from PAD-6. Results provide further support for specific cognitive, but not chronobiological, vulnerabilities in prediction of SAD. Limitations of the current sample are discussed. Results hold implications for future SAD research bridging the chronobiological and psychological disciplines with the ultimate aim of improved understanding, assessment, treatment, and prevention of SAD. ACKNOWLEDGEMENTS I would like to thank my committee members, Drs. Terry Rabinowitz, Tim Stickle, Mark Bouton, and Donna Toufexis, for their support of this project and guidance throughout my graduate training. I am honored to have you as part of my capstone graduate experience. I would like to express my deepest gratitude to my mentor, Dr. Kelly Rohan, for her incredible support, guidance, caring, and dedication to my graduate training. Her enthusiasm for my research and continued support of my career has made this a wonderful experience. My sincerest thanks to Dr. Al Lewy for his support of my research career from square one: my research assistantship through the fellowship funding this project. Without that first step, I may not have come this far. I am indebted to Dr. Kathryn Roecklein of the University of Pittsburgh for her collaboration and consultation on this project, with a special thanks to her research assistant, Lewis Schneider, for his assistance in data preparation. My wonderful lab mates – Yael Nillni, Lilya Sitnikov, Maggie Evans, Sheau-Yan Ho, and Jonah Meyerhoff – have made the past 7 years extraordinary. A special thanks to Dr. Yael Nillni for her mentorship in my initial years of graduate study. She set a wonderful example. ii I could not have completed the project without the help of my undergraduate research assistants: Ashley Deeb, Benjamin Cornell, Dan Cheney, and Craig Pastel, who generously volunteered their time to assist in data management. I am grateful to the University of Vermont Center of Biomedical Research Excellence for providing support for immunoassay, with a special thanks to Thomm Buttolph for his light-hearted approach to immunoassay training. A special thanks to Alan Howard and Dr. Marketa Krenek for their statistical consultation. I would like to acknowledge the National Institute of Mental Health for funding my graduate fellowship training (1F31MH094046-01A1) and making this project possible. I am extremely grateful to the Department of Psychological Science at the University of Vermont for providing supplementary research funding and continued support of my research. Lastly, I would like to thank my loving friends and family who have been by my side throughout this journey. I am especially grateful to Ben Mahon for his support in my pursuit of graduate study. And, to my Mom, who continues to inspire me through her love, spirit, and aspiration to make a true difference. It is to all of you that I owe this accomplishment. Thank you. iii TABLE OF CONTENTS ACKNOWLEDGMENTS ........................................................................................ ii LIST OF TABLES ................................................................................................... vi LIST OF FIGURES ................................................................................................... viii CHAPTER 1: Seasonal Affective Disorder (SAD) .................................................... 1 Prevalence Across Latitude ............................................................................. 2 Environmental Triggers of SAD ..................................................................... 3 Chronobiological Vulnerability to SAD ......................................................... 4 Mechanisms Linking Photoperiod to Circadian Rhythmicity ........................ 22 Psychological Vulnerability to SAD .............................................................. 26 Integrative Models of SAD ............................................................................ 32 Limitations of SAD Research ........................................................................ 33 CHAPTER 2: The Current Project ............................................................................ 35 Study Aims and Hypotheses ............................................................................ 35 CHAPTER 3: Method .............................................................................................. 38 Participants ...................................................................................................... 38 Procedure ......................................................................................................... 39 Measures ........................................................................................................ 43 Data Analytic Method .................................................................................... 48 CHAPTER 4: Results ............................................................................................... 54 Participant Flow ............................................................................................... 54 Aim 1 ............................................................................................................... 58 Aim 2 ............................................................................................................... 74 iv CHAPTER 5: Discussion ........................................................................................... 87 Aim 1 .............................................................................................................. 88 Aim 2 .............................................................................................................. 97 Study Limitations ........................................................................................... 102 Future Directions ........................................................................................... 105 Conclusions ................................................................................................... 108 REFERENCES .......................................................................................................... 111 APPENDIX A ............................................................................................................ 126 APPENDIX B ............................................................................................................ 127 APPENDIX C ...........................................................................................................
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