The Effect of Depersonalization and Derealization Symptoms
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THE EFFECT OF DEPERSONALIZATION AND DEREALIZATION SYMPTOMS ON OLFACTION AND OLFACTORY HEDONICS Thesis Submitted to The College of Arts and Sciences of the UNIVERSITY OF DAYTON In Partial Fulfillment of the Requirements for The Degree of Master of Arts in Psychology By Rhiannon A. Gibbs UNIVERSITY OF DAYTON Dayton, Ohio May 2018 THE EFFECT OF DEPERSONALIZATION AND DEREALIZATION SYMPTOMS ON OLFACTION AND OLFACTORY HEDONICS Name: Gibbs, Rhiannon A. APPROVED BY: _______________________________________ Julie Walsh-Messinger, Ph.D. Faculty Advisor ______________________________________ Roger R. Reeb, Ph.D. Committee Member ______________________________________ Jackson A. Goodnight, Ph.D. Committee Member Concurrence: _______________________________________ Lee Dixon, Ph.D. Chair, Department of Psychology ii © Copyright by Rhiannon A. Gibbs All rights reserved 2018 ABSTRACT THE EFFECT OF DEPERSONALIZATION AND DEREALIZATION SYMPTOMS ON OLFACTION AND OLFACTORY HEDONICS Name: Gibbs, Rhiannon A. University of Dayton Advisor: Dr. Julie Walsh-Messinger. Depersonalization and derealization symptoms affect sensation, perception, and emotion, producing subjective experiences of unreality and affective numbing (Simeon, 2004). Abnormalities in the amygdala, which is associated with emotional reactions such as anxiety and fear (LeDoux, 1993), have been observed in depersonalization and derealization and other psychiatric disorders, such as anxiety and depression (Sierra & Berrios, 1998). Olfactory deficits have been posited as a potential marker for psychiatric disorders, including depression (Atanasova, 2008), which may be related to the close neural connections between the olfaction system and the amygdala (Stockhorst & Pietrowsky, 2004). However, no previous studies have examined the relationship between depersonalization/derealization and olfactory functioning. Thus, this study investigated whether depersonalization and derealization symptom severity was correlated with odor identification ability, odor detection threshold, and hedonic ratings of odors in an undergraduate sample (N = 92). It was hypothesized that: 1) odor iii identification ability would be negatively correlated with reported depersonalization and derealization symptoms; 2) odor detection threshold would be positively correlated with depersonalization and derealization symptoms; and 3) both pleasantness and unpleasantness ratings of odors would be negatively correlated with depersonalization and derealization symptoms. Participants (N = 92) were administered two olfaction testing batteries, and completed self-report measures of depersonalization, depression, and anxiety. Results did not support the main hypotheses. Exploratory analyses revealed a significant sex by depersonalization interaction for odor identification ability, indicating that females with higher levels of depersonalization were less able to correctly identify odorants. Future research in clinical samples is needed to confirm this interaction. iv ACKNOWLEDGEMENTS First of all, I would like to thank my incredible advisor, Dr. Julie Walsh- Messinger, for her unwavering support and guidance. Her sound advice, and at times constructive criticisms, were invaluable to the development of this project. I could not have imagined a better mentor to work with and extend to her my deepest gratitude. Secondly, I would like to thank the members of my committee, Dr. Roger Reeb and Dr. Jackson Goodnight, for their insight, encouragement, and difficult questions. Their input was extraordinarily helpful in the development of this study. I would also like to thank Russell Mach, Julia Weideman, Lisa Stone, Lauren Olson, Maia Mclin, and all other current and former members of the Personality and Smell lab, for their assistance in collecting and entering data. Their hard work made this study possible. Finally, I would like to thank my wonderful family, friends, and fellow classmates at the University of Dayton. Their love, friendship, and support have been unfailing for the last two and a half years, and this project could not have happened without it. Thank you. v TABLE OF CONTENTS ABSTRACT……………………………………………………………………………...iii ACKNOWLEDGMENTS………………………………………………………………...v LIST OF TABLES……………………………………………….....................................vii INTRODUCTION………………………………………………………………………...1 METHODS...…………………………………………………………………………….16 RESULTS………………………………………………………………………………..20 DISCUSSION……………………………………………………………………………29 REFERENCES…………………………………………………………………………..35 APPENDICES A. Cambridge Depersonalization Scale….…………………………………...….42 B. Generalized Anxiety Disorder 7 Item Scale…….………………………….....44 C. Center for Epidemiologic Studies Depression Scale Revised ……………......45 D. Odor Hedonic Rating Scales…………..……………………………………...47 vi LIST OF TABLES Table 1. Means and Standard Deviations for All Measures……………………………20 Table 2. Tests of Normality…………………………………………………………….21 Table 3. Correlation Table……………………………………………………………...21 Table 4. Results of Multiple Regression Analyses- Odor Identification……………….22 Table 5. Results of Multiple Regression Analyses-Threshold Detection………………22 Table 6. Results of Multiple Regression Analyses- Unpleasantness and Pleasantness Ratings…………………………………………………………………………………...23 Table 7. Means and Standard Deviations for all Measures, by Sex……………………24 Table 8. Independent Samples T-Tests for all Measures, by Sex………………………24 Table 9. Results of Multiple Regression Analyses in Males- Odor Identification……..24 Table 10. Results of Multiple Regression Analyses- Females…………………………..25 Table 11. Results of Multiple Regression Analyses in Males- Threshold Detection……25 Table 12. Results of Multiple Regression Analyses in Females- Threshold Detection….25 Table 13. Results of Multiple Regression Analyses in Males- Unpleasantness and Pleasantness Ratings……………………………………………………………………..26 Table 14. Results of Multiple Regression Analyses in Females- Unpleasantness and Pleasantness……………………………………………………………………………...26 Table 15. Mean Differences for Sex x Depersonalization Group Interaction…………...27 vii CHAPTER 1 INTRODUCTION Depersonalization is a perceptual anomaly characterized by subjective feelings of unreality and alterations in the perception of the self. This sensation involves feelings of detachment from oneself, alterations in the perception of one’s identity, and/or emotional numbing (APA, 2013). Common descriptions include feeling numb, robotic, unreal, or as though one’s body is foreign. Derealization, by contrast, is characterized by subjective feelings of unreality and/or detachment in relation to external surroundings. Common descriptions include feeling as though the world is hazy, foggy, dreamlike, or like there is a pane of glass in front of one’s eyes (Simeon, 2004). The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM- 5) classifies depersonalization/derealization disorder (DDD) as a dissociative disorder characterized by chronic and/or recurring symptoms of depersonalization and/or derealization. No operational time limit for frequency and duration of symptoms is specified, but transient symptoms generally are not indicative of a disorder. Symptoms must also cause clinically significant distress and/or impairment in functioning, and reality testing must remain intact. Symptoms must not be better accounted for by another mental disorder (such as panic disorder, posttraumatic stress disorder, or another dissociative disorder,) and must not be caused by a general medical condition or drug and 1 alcohol use (APA, 2013). Prevalence rate estimates of DDD range from 0.8 to 2.8 percent in the general population (APA, 2013). In non-clinical populations, the lifetime prevalence of subclinical, transient depersonalization symptoms is estimated at between 26 and 74 percent (Hunter, Sierra, & David, 2004). DSM-5 estimates the lifetime prevalence of subclinical symptoms to be roughly 50 percent in the general population (APA, 2013). As well, Aderibigbe, Bloch, and Waler (2001) found annual prevalence rates for depersonalization experiences in a rural population to be roughly 23 percent. These experiences were categorized as non-clinical because participants were asked only if they had experienced depersonalization symptoms for at least one hour, or at least 3 times in the past year (Aderibigbe et al., 2001). Simeon (2004) suggests that depersonalization and derealization symptoms are more common in the general population than is often believed by the psychiatric community. It is probable that symptoms are frequently mistaken as variations of depression and anxiety (Simeon, 2004). Clinical features of depersonalization and derealization are based on subjective experiences of unreality, and remain difficult to define and identify by clinicians. One study presented findings from 204 cases of DDD and identified several clinical features of the disorder, including the tendency to be chronic, highly co-morbid with depression and anxiety, and associated with trauma, non-traumatic psychological stressors, and substance misuse (Baker et al., 2003). Other studies have also identified high prevalence of depersonalization/derealization symptoms among those with panic disorder, unipolar depression, and posttraumatic stress disorder (Hunter et al., 2004,) and high co- morbidities of DDD with mood, anxiety, and personality disorders (Simeon, Knutelska, 2 Nelson & Guralnik, 2001). Given these frequently observed co-morbidities, it is possible that the neurological mechanisms of these disorders overlap. Along with perceptual