Occupation, Environment, and Mental Health
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Occupation, Environment, and Mental Health The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:37945632 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Other Posted Material, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#LAA Occupation, Environment, and Mental Health Alexander Chu Wu A Dissertation Submitted to the Faculty of The Harvard T.H. Chan School of Public Health in Partial Fulfillment of the Requirements for the Degree of Doctor of Science in the Department of Environmental Health Harvard University Boston, Massachusetts May, 2018 Dissertation Advisor: Dr. Marc G. Weisskopf Alexander Chu Wu Occupation, Environment, and Mental Health ABSTRACT Despite a decades-old call for better understanding of the role of environmental pollutant influences on mental health, a comprehensive review of the literature on non-occupational exposures to environmental pollutants and adult mental health has not been performed. Second, the Germanwings Flight 9525 crash has brought the sensitive subject of airline pilot mental health to the forefront in aviation. Third, scientists use biomarkers to evaluate metal exposures. One biomarker, toenails, is easily obtained and minimally invasive, but less commonly used as a biomarker of exposure. Their utility will depend on understanding characteristics of their variation in a population over time. Fourth, toenails are less commonly used as a biomarker of exposure and has not been evaluated on its relationship with psychiatric outcomes; particularly depression and anxiety. We reviewed the existing literature on environmental pollutant exposures and three specific mental health outcomes (depression, anxiety, and suicide) published on PubMed, Embase, Web of Science, and PsychINFO through the end of year 2016. Second, we conducted a descriptive cross-sectional study via an anonymous web-based survey administered to airline pilots between April and December 2015. Third, we utilized linear mixed models to assess correlation between toenail metal concentrations in multiple toenail samples from the same subject collected years apart among participants in the VA Normative Aging Study (NAS). ii Fourth, we utilized multivariate linear and logistic mixed models to assess the association with five toenail metals and outcomes measured by the Brief Symptom Index (BSI). The current literature, although limited, clearly suggests many kinds of environmental exposures may be risk factors for depression, anxiety, and suicide. Overall, the strongest studies appear to be of air pollution exposure. Second, hundreds of pilots currently flying are managing depressive symptoms perhaps without the possibility of treatment due to the fear of negative career impacts. Third, our results suggest that lead, arsenic, cadmium, manganese, and mercury levels from toenail clippings can reasonably reflect exposures over several years in elderly men in the NAS. Fourth, our study tentatively suggests that toenails from NAS participants may be an important biomarker to measure the association between metals and symptoms of depression or anxiety. iii TABLE OF CONTENTS ABSTRACT ................................................................................................................................................................ II LIST OF FIGURES WITH CAPTIONS ................................................................................................................. VI LIST OF TABLES WITH CAPTIONS .................................................................................................................. VII ACKNOWLEDGEMENTS ..................................................................................................................................... XII CHAPTER 1. A REVIEW OF NON-OCCUPATIONAL EXPOSURES TO ENVIRONMENTAL POLLUTANTS AND ADULT MENTAL HEALTH: DEPRESSION, ANXIETY, AND SUICIDE. ................. 1 Abstract ..................................................................................................................................................................... 2 Introduction ............................................................................................................................................................... 4 Methods ..................................................................................................................................................................... 7 Results ..................................................................................................................................................................... 10 Depression .......................................................................................................................................................... 13 Anxiety ............................................................................................................................................................... 68 Suicide ................................................................................................................................................................ 89 Discussion ............................................................................................................................................................. 109 Conclusion............................................................................................................................................................. 114 Bibliography .......................................................................................................................................................... 115 CHAPTER 2. AIRPLANE PILOT MENTAL HEALTH AND SUICIDAL THOUGHTS: A CROSS- SECTIONAL DESCRIPTIVE STUDY VIA ANONYMOUS WEB-BASED SURVEY ................................... 133 Abstract…………………..……………………………………………………………………………………….134 Background………………………..……………………………………………………………………………...135 Methods……………………………..……………………………………………………………………………135 Results………………………………………..……………………………………………………………….…..136 Discussion……………………………………..…………………………………………………………….……139 Conclusion………………………………………..………………………………………………………………143 Bibliography…………………………………………………………………………………...…………………144 Appendix: Chapter 2, Supplemental ..................................................................................................................... 146 Airline pilot mental health screening ................................................................................................................ 146 Aviation Medical Examiner .............................................................................................................................. 148 Additional Pilot Testing .................................................................................................................................... 149 Appendix Bibliography ..................................................................................................................................... 149 CHAPTER 3. CORRELATION OVER TIME OF TOENAIL METALS AMONG PARTICIPANTS IN THE VA NORMATIVE AGING STUDY FROM 1992 TO 2014................................................................................. 152 Abstract ................................................................................................................................................................. 153 Introduction ........................................................................................................................................................... 155 Methods ................................................................................................................................................................. 157 Study Population ............................................................................................................................................... 157 Metals Analysis................................................................................................................................................. 157 iv Statistical Methods ............................................................................................................................................ 160 Code availability ............................................................................................................................................... 163 Results ................................................................................................................................................................... 163 Demographics ................................................................................................................................................... 163 Metal Measurement Occasions ......................................................................................................................... 165 Metal Concentrations ........................................................................................................................................ 165 Correlations between Metals ............................................................................................................................. 167 Correlations of Toenail Metal Measurements over Time ................................................................................. 167 Discussion